Showing papers by "University of St Andrews published in 1996"
TL;DR: Direct in vivo evidence of a differential neural response in the human amygdala to facial expressions of fear and happiness is reported, providing direct evidence that the humangdala is engaged in processing the emotional salience of faces, with a specificity of response to fearful facial expressions.
Abstract: The amygdala is thought to play a crucial role in emotional and social behaviour. Animal studies implicate the amygdala in both fear conditioning and face perception. In humans, lesions of the amygdala can lead to selective deficits in the recognition of fearful facial expressions and impaired fear conditioning, and direct electrical stimulation evokes fearful emotional responses. Here we report direct in vivo evidence of a differential neural response in the human amygdala to facial expressions of fear and happiness. Positron-emission tomography (PET) measures of neural activity were acquired while subjects viewed photographs of fearful or happy faces, varying systematically in emotional intensity. The neuronal response in the left amygdala was significantly greater to fearful as opposed to happy expressions. Furthermore, this response showed a significant interaction with the intensity of emotion (increasing with increasing fearfulness, decreasing with increasing happiness). The findings provide direct evidence that the human amygdala is engaged in processing the emotional salience of faces, with a specificity of response to fearful facial expressions.
1,954 citations
TL;DR: LiMnO2 as discussed by the authors is a new material, which is structurally analogous to LiCoO2, which has been much studied as a positive electrode material for rechargeable lithium batteries.
Abstract: RECHARGEABLE lithium batteries can store more than twice as much energy per unit weight and volume as other rechargeable batteries1,2. They contain lithium ions in an electrolyte, which shuttle back and forth between, and are intercalated by, the electrode materials. The first commercially successful rechargeable lithium battery3, introduced by the Sony Corporation in 1990, consists of a carbon-based negative electrode, layered LiCoO2 as the positive electrode, and a non-aqueous liquid electrolyte. The high cost and toxicity of cobalt compounds, however, has prompted a search for alternative materials that intercalate lithium ions. One such is LiMn2O4, which has been much studied as a positive electrode material4–7; the cost of manganese is less than 1% of that of cobalt, and it is less toxic. Here we report the synthesis and electrochemical performance of a new material, layered LiMnO2, which is structurally analogous to LiCoO2. The charge capacity of LiMnO2 (∼270mAhg–1) compares well with that of both LiCoO2 and LiMn2O4, and preliminary results indicate good stability over repeated charge–discharge cycles.
1,301 citations
TL;DR: It is demonstrated that physiological responses to GDNF require the presence of a novel glycosyl-phosphatidylinositol (GPI)-linked protein (designated GDNFR-α) that is expressed on GDNF-responsive cells and binds GDNF with a high affinity, which supports the hypothesis that GDNF uses a multi-subunit receptor system in which GDN FR-α and Ret function as the ligand-binding and signalling components.
Abstract: Glial-cell-line-derived neurotrophic factor (GDNF) is a potent survival factor for central and peripheral neurons, and is essential for the development of kidneys and the enteric nervous system. Despite the potential clinical and physiological importance of GDNF, its mechanism of action is unknown. Here we show that physiological responses to GDNF require the presence of a novel glycosyl-phosphatidylinositol (GPI)-linked protein (designated GDNFR-alpha) that is expressed on GDNF-responsive cells and binds GDNF with a high affinity. We further demonstrate that GDNF promotes the formation of a physical complex between GDNFR-alpha and the orphan tyrosin kinase receptor Ret, thereby inducing its tyrosine phosphorylation. These findings support the hypothesis that GDNF uses a multi-subunit receptor system in which GDNFR-alpha and Ret function as the ligand-binding and signalling components, respectively.
1,094 citations
TL;DR: In this paper, a new method for estimating the geographical distribution of plant and animal species from incomplete field survey data is developed, by extending a logistic model to include an extra covariate which is derived from the responses at neighbouring squares, known as an autologistic model.
Abstract: 1. A new method for estimating the geographical distribution of plant and animal species from incomplete field survey data is developed. 2. Wildlife surveys are often conducted by dividing a study region into a regular grid and collecting data on abundance or on presence/absence from some or all of the squares in the grid. Generalized linear models (GLMs) can be used to model the spatial distribution of a species within such a grid by relating the response variable (abundance or presence/absence) to spatially referenced covariates. 3. Such models ignore or at best indirectly model dependence on unmeasured covariates, and the intrinsic spatial autocorrelation arising for example in gregarious populations. 4. We describe a procedure for use with presence/absence data in which spatial autocorrelation is modelled explicitly. We achieve this by extending a logistic model to include an extra covariate which is derived from the responses at neighbouring squares. The extended model is known as an autologistic model. 5. To allow fitting of the autologistic model when only a random sample of squares is surveyed, we use the Gibbs sampler to predict presence/absence at unsurveyed squares. 6. We compare the autologistic model with the ordinary logistic model using red deer census data. Both models are fitted to a subsample of 20% of the data and results are compared with the 'true' abundance and spatial distribution indicated by the full census. We conclude that the autologistic model is superior for estimating the spatial distribution of the deer, whereas the ordinary logistic model yields more precise estimates of the overall number of squares occupied by deer at the time of the survey.
678 citations
TL;DR: Event-related potentials were recorded during the test phase of a recognition memory task in two experiments and offer little support for the view that recognition judgements with and without retrieval of study context depend upon qualitatively different memory processes or systems.
Abstract: Summary Event-related potentials (ERPs) were recorded during the test phase of a recognition memory task in two experiments. In both experiments subjects made initial old/new judgements to visually presented words, and for words judged old, indicated in which of two voices (male/female) the words had been heard at study. In the second experiment only, subjects had the option to signal that they were uncertain about the status of a test word. Two positive-going ERP effects differentiated the ERPs evoked by correctly recognized old worlds from those evoked by words correctly judged new. The two effects differed in their scalp topography and time course, and were both of greater magnitude in the ERPs evoked by recognized words for which a correct voice judgement was made. The findings are consistent with the view that multiple neural systems underlie the ability to recognize an item and to recall its study context. However, the findings offer little support for the view, articulated in certain ‘dual-process’ models of recognition memory, that recognition judgements with and without retrieval of study context depend upon qualitatively different memory processes or systems.
592 citations
TL;DR: Face perception and emotion recognition were investigated in a group of people with Huntington's disease and matched controls, showing that the recognition of some emotions is more impaired than others and disgust is a prime candidate.
Abstract: Face perception and emotion recognition were investigated in a group of people with Huntington's disease and matched controls. In conventional tasks intended to explore the perception of age, sex, unfamiliar face identity (Benton test) and gaze direction from the face, the Huntington's disease group showed a borderline impairment of gaze direction perception and were significantly impaired on unfamiliar face matching. With a separate set of tasks using computerinterpolated ('morphed') facial images, people with Huntington's disease were markedly impaired at discriminating anger from fear, but experienced less difficulty with continua varying from male to female, between familiar identities, and from happiness to sadness. In a further test of recognition of facial expressions of basic emotions from the Ekman and Friesen (1976) series, interpolated images were created for six continua that lay around the perimeter of an emotion hexagon (happiness-surprise; surprise-fear; fear-sadness; sadness-disgust; disgust-anger; anger-happiness). In deciding which emotion these morphed images were most like, people with Huntington's disease again showed deficits in the recognition of anger and fear, and an especially severe problem with disgust, which was recognized only at chance level. A follow-up study with tests of facially and vocally expressed emotions confirmed that the recognition of disgust was markedly poor for the Huntington's disease group, still being no better than chance level. Questionnaires were also used to examine self-assessed emotion, but did not show such striking problems. Taken together, these data reveal severe impairments of emotion recognition in Huntington's disease, and show that the recognition of some emotions is more impaired than others. The possibility that certain basic emotions may have dedicated neural substrates needs to be seriously considered: among these, disgust is a prime candidate.
482 citations
TL;DR: It is indicated that NO-donors can directly inhibit the DNA binding activity of NF-kappaB family proteins, suggesting that cellular NO provides another control mechanism for modulating the expression ofNF- kappaB-responsive genes.
Abstract: It has been suggested that the NF-kappaB transcription factor family may mediate expression of the gene encoding the cytokine-inducible form of nitric oxide synthase (iNOS). To establish if nitric oxide (NO) could in turn affect activity of NF-kappaB, the ability of NO-donor compounds to influence NF-kappaB DNA binding activity in vitro was investigated. NO-donor compounds sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP) both inhibited the DNA binding activity of recombinant NF-kappaB p50 and p65 homodimers and of p50-p65 heterodimers. Inhibition of NF-kappaB p50 DNA binding by NO-donor compounds involved modification of the conserved redox-sensitive C62 residue, as a C62S p50 mutant was significantly more resistant to SNP-mediated inactivation. Non-reducing SDS-polyacrylamide gel electrophoresis demonstrated that SNP could inhibit p50 DNA binding by mechanisms other than the formation of intersubunit disulphide bonds involving p50 residue C62. Electrospray ionization mass spectrometry of a synthetic NF-kappaB p5O peptide containing the C62 residue suggested that NO gas can modify C62 by S-nitrosylation. This study indicates that NO-donors can directly inhibit the DNA binding activity of NF-kappaB family proteins, suggesting that cellular NO provides another control mechanism for modulating the expression of NF-kappaB-responsive genes.
465 citations
TL;DR: In this article, a spiral phaseplate was used at millimetre-wave frequencies to transform a free-space, fundamental Hermite-Gaussian mode into a Laguerre Gaussian mode with an azimuthal phase component.
419 citations
TL;DR: The CHEVIE package as mentioned in this paper is a computer algebra package which collects data and programs for the representation theory of finite groups of Lie type and associated structures, including Weyl groups and Iwahori-Hecke algebras.
Abstract: CHEVIE is a computer algebra package which collects data and programs for the representation theory of finite groups of Lie type and associated structures. We explain the theoretical and conceptual background of the various parts of CHEVIE and we show the usage of the system by means of explicit examples. More precisely, we have sections on Weyl groups and Iwahori-Hecke algebras, generic character tables of series of finite groups of Lie type, and cyclotomic algebras.
391 citations
TL;DR: To the authors' knowledge, this is the first experimental evidence of chimpanzee imitation in a functional task designed to simulate foraging behavior hypothesized to be transmitted culturally in the wild.
Abstract: Observational learning in chimpanzees and young children was investigated using an artificial fruit designed as an analog of natural foraging problems faced by primates. Each of 3 principal components could be removed in 2 alternative ways, demonstration of only one of which was watched by each subject. This permitted subsequent imitation by subjects to be distinguished from stimulus enhancement. Children aged 2–4 years evidenced imitation for 2 components, but also achieved demonstrated outcomes through their own techniques. Chimpanzees relied even more on their own techniques, but they did imitate elements of 1 component of the task. To our knowledge, this is the first experimental evidence of chimpanzee imitation in a functional task designed to simulate foraging behavior hypothesized to be transmitted culturally in the wild.
387 citations
TL;DR: The diversity of responses to flooding in wild plants suggests that, depending on the life strategy and habitat of the species, many different mechanisms may be involved in adapting plants to survive periods of inundation and no one mechanism on its own is adequate for ensuring survival.
Abstract: Past research into flooding tolerance and oxygen shortages in plants has been motivated largely by cultivation problems of arable crops. Unfortunately, such species are unsuitable for investigating the physiological and biochemical basis of anoxia-tolerance as selection has reduced any tolerance of anaerobiosis and anaerobic soil conditions that their wild ancestors might have possessed, Restoration of anoxia-tolerance to species that have lost this property is served better by physiological and molecular studies of the mechanisms that are employed in wild species that still possess long-term anoxia-tolerance. Case studies developing these arguments are presented in relation to a selection of crop and wild species, The flooding sensitivity and metabolism of maize is compared in relation to rice in its capacity for anaerobic germination, The sensitivity of potato to flooding is related to its disturbed energy metabolism and inability to maintain functioning membranes under anoxia and post-inoxia, By contrast, long-term anoxia-tolerance in the American cranberry (Vaccinium macrocarpon) and the arctic grass species Deschampsia beringensis can be related to the provision and utilization of carbohydrate reserves. Among temperate species, the sweet flag (Acorus calamus) shows a remarkable tolerance of anoxia in both shoots and roots and is also able to mobilize carbohydrate and maintain ATP levels during anoxia as well as preserving membrane lipids against anoxic and post-anoxic injury. Phragmites australis and Spartina alterniflora, although anoxia-tolerant, are both sulphide-sensitive species which can pre-dispose them to the phenomenon of die-back in stagnant, nutrient-rich water. Glyceria maxima adapts to flooding through phenological adaptations with a seasonal metabolic tolerance of anoxia confined to winter and spring which, combined with a facility for root aeration and early spring growth, allows rapid colonization of sites with only shallow flooding. The diversity of responses to flooding in wild plants suggests that, depending on the life strategy and habitat of the species, many different mechanisms may be involved in adapting plants to survive periods of inundation and no one mechanism on its own is adequate for ensuring survival.
TL;DR: A neuronal population in the anterior part of the superior temporal polysensory area (STPa) both sensitive to form (heads and bodies) and selective for motion direction is reported, showing that the response of some of these cells is selective for both the motion and the form of a single object, not simply the juxtaposition of appropriate form and motion signals.
Abstract: 1. Processing of visual information in primates is believed to occur in at least two separate cortical pathways, commonly labeled the "form" and "motion" pathways. This division lies in marked contrast to our everyday visual experience, in which we have a unified percept of both the form and motion of objects, implying integration of both types of information. We report here on a neuronal population in the anterior part of the superior temporal polysensory area (STPa) both sensitive to form (heads and bodies) and selective for motion direction. 2. A total of 161 cells were found to be sensitive to body form and motion. The majority of cells (125 of 161, 78%) responded to only one combination of view and direction (termed unimodal cells, e.g., left profile view moving left, not right profile moving left, or left profile moving right). We show that the response of some of these cells is selective for both the motion and the form of a single object, not simply the juxtaposition of appropriate form and motion signals. 3. A smaller number of cells (9 of 161, 6%) responded selectively to two opposite combinations of view and direction (e.g., left profile moving left and right profile moving right, but no other view and direction combinations). A few cells (4 of 161, 2%) showed "object-centered" selectivity to view and direction combinations, responding to all directions of motion where the body moves in a direction compatible with the direction it faces, for example, responding to left profile going left, right profile going right, face view moving toward the observer, back view moving away from the observer, but not other view and direction combinations. 4. The majority of the neurons (106 of 138, 77%) selective for specific body view and direction combinations responded best to compatible motion (e.g., left profile moving left), and one fourth (23%) showed selectivity for incompatible motion (e.g., right profile moving left). 5. The relative strengths of motion and form inputs to cells in STPa conjointly sensitive to information about form and motion were assessed. The majority of the responses (95%) were characterized as showing nonlinear summation of form and motion inputs. 6. The capacity to discriminate different directions and different forms was compared across three populations of STPa cells, namely those sensitive to 1) form only, 2) motion only, and 3) both form and motion. The selectivity of the latter class could be predicted from combinations of the other two classes. 7. The response latencies of cells selective for form and motion are on average coincident with cells selective for direction of motion (but not stimulus form). Both these cell populations have response latencies on average 20 ms earlier than cells selective for static form. 8. Calculation of the average of early response latency cells (cell whose response latency was under the sample mean) suggests that direction information is present in cell responses some 35 ms before form information becomes evident. Direction information and form information become evident within 5 ms of each other in the average late response latency cells (those cells whose response latency was greater than the sample mean). Inputs relating to movement show an initial response period that does not discriminate direction. The quality of initial direction discrimination appeared to be independent of response latency. The initial discrimination of form was related to response latency in that cells with longer response latencies showed greater initial discrimination of form in their responses. We argue that these findings are consistent with form inputs arriving to area STPa approximately 20 ms after motion inputs into area STPa.
TL;DR: It is concluded that the prefrontal cortex, especially in the right hemisphere, is more active when a retrieval attempt succeeds than when it fails, consistent with the idea that the cortex supports processes that operate selectively on the products of memory retrieval.
Abstract: Six subjects underwent PET scans while they performed three versions of a recognition memory test for words and three versions of a control task. In each memory condition, the subjects discriminated between words presented in a prescan study list and words new to the experiment. During the 30 s scanning interval, the ratio of old and new words was 0: 20, 4: 16 or 16: 4, depending on the experimental condition. Outside this interval, the ratio was 50: 50 in all three conditions. The requirement in the control task was to discriminate between two character strings, the ratios of which were also manipulated during the 30 s scanning interval. Employing the control task as a covariate, analysis with statistical parametric mapping revealed that regional cerebral blood flow (rCBF) covaried with increasing density of old items in three regions of prefrontal cortex: right dorsolateral [Brodmann area (BA) 9/46], right medial (BA 32/8) and bilateral frontopolar cortex (BA 10). It is concluded that the prefrontal cortex, especially in the right hemisphere, is more active when a retrieval attempt succeeds than when it fails. This finding is consistent with the idea that the prefrontal cortex supports processes that operate selectively on the products of memory retrieval.
TL;DR: In this article, it was shown that the orbital angular momentum of the Laguerre-Gaussian mode is directly proportional to the azimuthal mode index, which is consistent with the interpretation that the angular angular momentum is a function of phase-matching conditions.
Abstract: Second-harmonic generation has been obtained by the use of Laguerre-Gaussian beams in a variety of mode orders. Each mode becomes doubled in frequency and transformed to a higher order. We show this to be a consequence of the phase-matching conditions. The experiment is consistent with the interpretation that the orbital angular momentum of the Laguerre-Gaussian mode is directly proportional to the azimuthal mode index $l$.
15 Dec 1996-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: In this article, the skeleton of an isolated null point in three dimensions consists of a "spine curve" and a "fan surface" and the kinematics of steady reconnection at such a null point are considered, depending on the nature of the imposed boundary conditions on the surface that encloses the null, in particular on a cylindrical surface with its axis along the spine.
Abstract: The skeleton of an isolated null point in three dimensions consists of a ‘spine curve’ and a ‘fan surface’. Two isolated magnetic field lines approach (or recede from) the null point from both directions along the spine, and a continuum of field lines recedes from (or approaches) the null in the plane of the fan surface. Two bundles of field lines approach the null point around the spine (one from each direction) and spread out near the fan. The kinematics of steady reconnection at such a null point is considered, depending on the nature of the imposed boundary conditions on the surface that encloses the null, in particular on a cylindrical surface with its axis along the spine. Three kinds of reconnection are discovered. In ‘spine reconnection’ continuous footpoint motions are imposed on the curved cylindrical surface, crossing the fan and driving singular jetting flow along the spine. In ‘fan reconnection’ continuous footpoint motions are prescribed on the ends of the cylinder, crossing the spine and driving a singular swirling motion at the fan. An antireconnection theorem is proved, which states that steady MHD reconnection in three dimensions with plasma flow across the spine or fan is impossible in an inviscid plasma with a highly subAlfvenic flow and uniform magnetic diffusivity. One implication of this is that reconnection tends to be an inherently nonlinear phenomenon. A linear theory for slow steady reconnection is developed which demonstrates explicitly the nature of the spine singularity in spine reconnection. Finally, the properties of separator reconnection’ in complex configurations containing two null points are discussed by means of analytical examples.
TL;DR: The crystal structure of a con A-trimannoside complex is determined and the structure provides a rationale for the high affinity of con A for N-linked glycans.
01 Dec 1996
TL;DR: In this article, the skeleton of an isolated null point in three dimensions consists of a "spine curve" and a "fan surface" and the kinematics of steady reconnection at such a null point are considered, depending on the nature of the imposed boundary conditions on the surface that encloses the null, in particular on a cylindrical surface with its axis along the spine.
Abstract: The skeleton of an isolated null point in three dimensions consists of a ‘spine curve’ and a ‘fan surface’. Two isolated magnetic field lines approach (or recede from) the null point from both directions along the spine, and a continuum of field lines recedes from (or approaches) the null in the plane of the fan surface. Two bundles of field lines approach the null point around the spine (one from each direction) and spread out near the fan. The kinematics of steady reconnection at such a null point is considered, depending on the nature of the imposed boundary conditions on the surface that encloses the null, in particular on a cylindrical surface with its axis along the spine. Three kinds of reconnection are discovered. In ‘spine reconnection’ continuous footpoint motions are imposed on the curved cylindrical surface, crossing the fan and driving singular jetting flow along the spine. In ‘fan reconnection’ continuous footpoint motions are prescribed on the ends of the cylinder, crossing the spine and driving a singular swirling motion at the fan. An antireconnection theorem is proved, which states that steady MHD reconnection in three dimensions with plasma flow across the spine or fan is impossible in an inviscid plasma with a highly subAlfvenic flow and uniform magnetic diffusivity. One implication of this is that reconnection tends to be an inherently nonlinear phenomenon. A linear theory for slow steady reconnection is developed which demonstrates explicitly the nature of the spine singularity in spine reconnection. Finally, the properties of separator reconnection’ in complex configurations containing two null points are discussed by means of analytical examples.
TL;DR: In this paper, the axial trapping forces within optical tweezers arising from Laguerre-Gaussian laser modes were numerically modeled for an 8 μm diameter sphere suspended in water.
Abstract: We numerically model the axial trapping forces within optical tweezers arising from Laguerre–Gaussian laser modes. For an 8 μm diameter sphere suspended in water, the higher-order modes produce an axial trapping force several times larger than that of the fundamental. Partial absorption results in a transfer of the orbital angular momentum from the Laguerre–Gaussian mode to the trapped particle. This results in the rotation of the particle by what may be called an optical spanner (wrench). For an absorption coefficient of α = 5700 m−1 and a laser power of 10 mW, we find that an 8 μm diameter sphere would acquire an angular acceleration of 10 × 104 rad s−2 and a limiting angular velocity of 0.2 rad s−1.
TL;DR: The aim of the paper is to establish firmly the phenomenon of an irrelevant picture effect and to demonstrate that the phenomenon can be used to investigate the characteristics of the visuo-spatial sketchpad and to establish a double dissociation between two types of interference, dynamic visual noise and irrelevant speech.
Abstract: The aim of the paper is to establish firmly the phenomenon of an irrelevant picture effect and to demonstrate that the phenomenon can be used to investigate the characteristics of the visuo-spatial sketchpad. Experiment 1 introduces the use of dynamic visual noise as an interfering technique. This technique is shown to cause interference with a word list learned under visual mnemonic mediation instructions but to cause no interference when the word list is learned under verbal mediation instructions. Experiment 2 serves both to replicate this selective interference effect and to illustrate how the dynamic visual noise technique can be used to characterize further the nature of interference in the visuo-spatial sketchpad. Experiment 3 confirms the robustness of the dynamic visual noise technique. Additionally, this experiment demonstrates a double dissociation between two types of interference, dynamic visual noise and irrelevant speech, and two types of mediation, rote and visual mnemonic.
TL;DR: The present data show that cholinergic neurons in the LDTg, but not the PPTg, regulate the activity of DA-containing neuron in the VTA, which complements previous data showing that cholinesterase inhibitors in the PTTg regulate DA- containing neurons inThe SNc.
Abstract: Microinjections of the cholinergic receptor agonist nicotine and the cholinesterase inhibitor neostigmine were made into the ventral tegmental area (VTA) of urethane-anesthetized rats, and dopamine (DA) efflux in the nucleus accumbens was measured using in vivo chronoamperometry. Dose-dependent increases in the chronoamperometric signals corresponding to increased DA efflux were observed in the nucleus accumbens of normal intact rats after cholinergic stimulation of the VTA. The source of the cholinergic input to the VTA was investigated by making excitotoxic lesions in either the laterodorsal tegmental nucleus (LDTg) or the pedunculopontine tegmental nucleus (PPTg). Compared with sham-operated control animals, which showed the same response as intact, nonlesioned rats, ibotenate lesions of the LDTg attenuated the stimulatory effects of intra-VTA neostigmine on DA efflux in the nucleus accumbens. In contrast, rats with ibotenate lesions of the PPTg showed normal nucleus accumbens DA eflux after intra-VTA injections of neostigmine. Such lesions in the PPTg attenuate DA efflux in the caudate-putamen stimulated by injections of neostigmine into the substantia nigra pars compacta (SNc). The present data show that cholinergic neurons in the LDTg, but not the PPTg, regulate the activity of DA-containing neurons in the VTA, which complements previous data showing that cholinergic neurons in the PPTg regulate DA-containing neurons in the SNc.
TL;DR: An ecological model of baboon social structure is presented which incorporates the effects of female-female competition, male-male competition, and predation pressure, and potentially accounts for wide variability in group size, group structure and social relationships within the genus Papio.
Abstract: Predictions of the model of van Schaik (1989) of female-bonding in primates are tested by systematically comparing the ecology, level of within-group contest competition for food (WGC), and patterns of social behaviour found in two contrasting baboon populations. Significant differences were found in food distribution (percentage of the diet from clumped sources), feeding supplant rates and grooming patterns. In accord with the model, the tendencies of females to affiliate and form coalitions with one another, and to be philopatric, were strongest where ecological conditions promoted WGC. Group fission in the population with strong WGC was “horizontal” with respect to female dominance rank, and associated with female-female aggression during a period of elevated feeding competition. In contrast, where WGC was low, females’ grooming was focused on adult males rather than other females. Recent evidence suggests that group fission here is initiated by males, tends to result in the formation of one-male groups, and is not related to feeding competition but to male-male competition for mates. An ecological model of baboon social structure is presented which incorporates the effects of female-female competition, male-male competition, and predation pressure. The model potentially accounts for wide variability in group size, group structure and social relationships within the genus Papio. Socio-ecological convergence between common baboons and hamadryas baboons, however, may be limited in some respects by phylogenetic inertia.
TL;DR: Physiological and molecular studies are revealing details of the mechanisms of temperature compensation and, combined with knowledge of the thermal history, are throwing new light on the process of evolution in this unique group of fish.
Abstract: There are few instances where a knowledge of the thermal physiology, habitats and lifestyles of a group of closely related species can be mapped onto a well-supported phylogeny and a detailed climatic history. The unique fish fauna of the Southern Ocean, dominated by a single group of fish whose phylogeny is known from traditional and molecular techniques, provides one such opportunity. Furthermore, these fish are living at an extreme temperature for marine organisms. Physiological and molecular studies are revealing details of the mechanisms of temperature compensation and, combined with knowledge of the thermal history, are throwing new light on the process of evolution in this unique group of fish.
TL;DR: It is demonstrated that in cells where proteasomal degradation is inhibited, signal induction by tumor necrosis factor α results in the rapid accumulation of higher molecular weight forms of IκBα that dissociate from NF-κB and are consistent with ubiquitin conjugation.
TL;DR: The presence of several constitutive antibacterial proteins, active against both gram-positive and gram-negative bacteria, in the haemocytes of the shore crab, Carcinus maenas is reported.
Abstract: Antibacterial peptides are important for non-specific host defence in many animals. They have been extensively characterized from mammals, amphibians, insects and chelicerates but have not so far been found in crustaceans. Here we report the presence of several constitutive antibacterial proteins, active against both gram-positive and gram-negative bacteria, in the haemocytes of the shore crab, Carcinus maenas. These proteins have molecular masses of >70 kDa, ≈45 kDa, ≈14 kDa and 6.5 kDa. The 6.5 kDa peptide has been purified to homogeneity by Sep Pak C18 extraction, gel filtration and reverse-phase HPLC. Partial N-terminal sequence analysis further shows that it is proline rich and shares more than 60% identity in a 28-amino-acid overlap with the mature form of bactenecin 7, an antimicrobial peptide from bovine neutrophils which belongs to the cathelicidin family of mammalian peptide antibiotics.
TL;DR: Preference shapes are shown to be genetic in origin, compatible with a coevolutionary model of signal-preference evolution, although it does not rule out an alternative model, sensory exploitation.
Abstract: The “shape” of a female mating preference is the relationship between a male trait and the probability of acceptance as a mating partner The shape of preferences is important in many models of sexual selection, mate recognition, communication, and speciation, yet it has rarely been measured precisely Here I examine preference shape for male calling song in a bushcricket (katydid) Preferences change dramatically between races of a species, from strongly directional to broadly stabilizing (but with a net directional effect) Preference shape generally matches the distribution of the male trait This is compatible with a coevolutionary model of signal-preference evolution, although it does not rule out an alternative model, sensory exploitation Preference shapes are shown to be genetic in origin
TL;DR: This is the first report of the cloning and characterization of plant genes that encode proteins with APS reductase activity and supports the suggestion that APS can be utilized directly, without activation to PAPS, as an intermediary substrate in reductive sulfate assimilation.
Abstract: Comparisons of A thaliana PRH-19, PRH-26, and PRH-43 deduced amino acid sequences (A) Sequence comparison with microbial PAPS reductases Amino acid residues identical to PRH-19 are indicated by a dot Breaks in the alignment are indicated by a dash Putative transit peptide cleavage sites in the PRH sequences are underlined Conserved amino acid regions are indicated by shaded boxes, and other conserved single amino acid residues are indicated by open boxes Sequences were aligned with the pileup program Compared microbial PAPS reductase sequences are: asper, Aspergillus nidulans SA gene (ref 17; GenBank accession no X82555X82555); scere, Saccharomyces cerevisiae strain 10197 MET16 gene (ref 16; GenBank accession no J05591J05591); thioc, Thiocapsa reseopersicina cysH gene (T Haverkamp, G Gisselman, and J D Schwenn, personal communication; GenBank accession no Z23169Z23169); ecoli, E coli K12 cysH gene (ref 15; GenBank accession no Y07525Y07525); styph, Salmonella typhimurium cysH gene (ref 18; GenBank accession no J05025J05025); anacy, Anacystis nidulans R2 par gene (ref 19; GenBank accession no M844476) (B) Comparison of the C-terminal sequence of the deduced PRH-19 amino acid sequence with other deduced homologous amino acid sequences Numbers refer to the amino acid residues in the deduced PRH-19 protein and in the proteins being compared Conserved amino acid residues are indicated by shaded boxes; highly conserved redox-active cysteine residues are indicated by black boxes Compared sequences are as follows: PRH19-arab, Arabidopsis PRH19 gene; Pdi-rat, rat protein disulfide isomerase gene (ref 20; GenBank accession no X02918X02918); ERp72-mouse, mouse endoplasmic reticulum protein gene ERp72 (ref 21; GenBank accession no J05186J05186); ERp60-bovin, bovine endoplasmic reticulum protein gene ERp60 (Hirano et al, personal communication; GenBank accession no D16235D16235); ERp5-medsau, golden hamster endoplasmic reticulum protein gene ERp5 (ref 22; GenBank accession no X62678X62678); ThiM-spiol, spinach thioredoxin m gene (ref 23; GenBank accession no P07591P07591); ThiF-Pisum, pea thioredoxin f gene (ref 24; GenBank accession no U35830U35830); ThiH-arab, Arabidopsis thioredoxin h gene (ref 25; GenBank accession no Z35473Z35473); Grx-oryza, rice glutaredoxin gene (ref 26; GenBank accession no X77150X77150)
TL;DR: The occurrence of the antiparallel dimers in both low pH crystal forms suggest that they are not an artefact of crystal packing, and may form in the low pH environment of the endosome.
TL;DR: Despite the growing wealth of information on the multiple roles and modes of action of neurotrophic factors, the neurotrophic hypothesis has remained the best explanation for how neuronal target fields in the developing peripheral nervous system regulate their innervation density.
Abstract: In the developing peripheral nervous system many neurons die shortly after their axons reach their target fields. This loss is thought to match the number of neurons to the size and requirements of their target fields because altering target field size before innervation affects the number of neurons that survive. The neurotrophic hypothesis provides an explanation for how target fields influence the size of the neuronal populations that innervate them. This hypothesis arose from work on nerve growth factor (NGF), the founder member of the neurotrophin family of secreted proteins. Its principal tenet is that the survival of developing neurons depends on the supply of a neurotrophic factor that is synthesized in limiting amounts in their target fields. The neurotrophic hypothesis has, however, been broadened by the demonstration that multiple neurotrophic factors regulate the survival of certain populations of neurons. For example, some neurons depend on several different neurotrophic factors which may act concurrently or sequentially during target field innervation. In addition, there are aspects of neurotrophin action that do not conform with the classic neurotrophic hypothesis. For example, the dependence of some populations of sensory neurons on particular neurotrophins before significant neuronal death takes place raises the possibility that the supply of these neurotrophins is not limiting for survival at this stage of development. There is also evidence that at stages before and after sensory neurons depend on target-derived neurotrophins for survival, neurotrophins act on at least some sensory neurons by an autocrine route. Yet despite the growing wealth of information on the multiple roles and modes of action of neurotrophic factors, the neurotrophic hypothesis has remained the best explanation for how neuronal target fields in the developing peripheral nervous system regulate their innervation density.