Showing papers in "Science in 1975"
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3,869 citations
TL;DR: The title of the Nobel Lecture of George Palade (1 August, p. 347) should have been "Intracellular aspects of the process of protein secretion."
Abstract: The title of the Nobel Lecture of George Palade (1 August, p. 347) should have been "Intracellular aspects of the process of protein secretion."
3,129 citations
2,758 citations
TL;DR: This article suggests mechanisms that may account for the differentiated state of dividing or nondividing cells and that also attempt to explain the ordered switching on or off of genes during development.
Abstract: It is generally accepted that the differentiated state of a given type of cell is associated with the activity of a particular set of genes, together with the total inactivity of those sets associated with the differentiation of other cell types. It is also clear that the differentiated state of dividing or nondividing cells is often extremely stable. In this article we suggest mechanisms that may account for this stability and that also attempt to explain the ordered switching on or off of genes during development. The phenotype of the organism depends on the genotype, and the genetic contribution from both parents is in almost all cases equal. Since the ultimate control of development resides in the genetic material, the actual program must be written in base sequences in the DNA. It is also clear that cytoplasmic components can have a powerful or overriding influence on genomic activity in particular cells, yet these cytoplasmic components are, of course, usually derived from the activity of genes at some earlier stage in development. A continual interaction between cytoplasmic enzymes and DNA sequences is an essential part of the model to be presented. Modification Enzymes In bacteria, enzymes exist which modify DNA by methylating adenine in the 6-position ( 1 ). These enzymes are extremely specific in their action; they modify bases at particular positions in short defined sequences of DNA, which, at least in some instances, form a palindrome. (A palindrome in DNA is an inverted duplication, with twofold rotational symmetry. The 3′ →...
1,708 citations
TL;DR: During the sleep cycle in cats, neurons localized to the posterolateral pole of the nucleus locus coeruleus and the nucleus subcoeruleus undergo discharge rate changes that are the opposite of those of the pontine reticular giant cells.
Abstract: During the sleep cycle in cats, neurons localized to the posterolateral pole of the nucleus locus coeruleus and the nucleus subcoeruleus undergo discharge rate changes that are the opposite of those of the pontine reticular giant cells. The inverse rate ratios and activity curves of these two interconnected populations are compatible with reciprocal interaction as a physiological basis of sleep cycle oscillation.
1,151 citations
TL;DR: Two longitudinal surveys based on random samples of high school students in New York State indicate four stages in the sequence of involvement with drugs: beer or wine, or both; cigarettes or hard liquor; marihuana; and other illicit drugs.
Abstract: Two longitudinal surveys based on random samples of high school students in New York State indicate four stages in the sequence of involvement with drugs: beer or wine, or both; cigarettes or hard liquor; marihuana; and other illicit drugs. The legal drugs are necessary intermediates between nonuse and marihuana. Whereas 27 percent of high school students who smoke and drink progress to marihuana within a 5- to 6-month follow-up period, only 2 percent of those who have not used any legal substance do so. Marihuana, in turn, is a crucial step on the way to other illicit drugs. While 26 percent of marihuana users progress to LSD, amphetamines, or heroin, only 1 percent of nondrug marihuana users and 4 percent of legal drug users do so. This sequence is found in each of the 4 years in high school and in the year after graduation. The reverse sequence holds for regression in drug use.
1,095 citations
TL;DR: Results indicate that the host-versus-graft reaction alone can enihance murine cvtomtiegalovirus in a chronicallY injected host atid maY help explain the high incidence of cvvtomegalov virus infection seen after renal and other allograft transplantation.
Abstract: C3H/He mice chronically infected with murine cYtomegalo virus were given skin allografis fromti histoincompatible BALB/c donors. A significant inicrease in cvtomegalovirus titers occurred within 3 days after placement oJ'the graft in the spleens and kidneYs oJ' the allograft recipients as compared with control aninmals. No significant changes in virus titers were detected in the salivary gland, lung, liver, or blood ofallograJi recipients. These results indicate that the host-versus-graft reaction alone can enihance murine cvtomtiegalovirus in a chronicallY injected host atid maY help explaini the high incidence ofcvvtomegalovirus infection seen after renal and other allograft transplantation
1,083 citations
TL;DR: Results give morphological support for a transmitter (or modulator) role of substance P in the nervous system of the rat and the cat.
Abstract: Antibodies to substance P with a high titer have been produced and used in immunohistochemical studies on the peripheral and central nervous system of the rat and the cat. Evidence was obtained for the localization of substance P in a certain population of primary sensory neurons, probably small nerve cells with unmyelinated processes. Substance P or a peptide similar to it was also observed in cell bodies in the medial habenula and in probable nerve terminals in many brain areas. The results give morphological support for a transmitter (or modulator) role of substance P in the nervous system.
1,009 citations
TL;DR: Compared to the inhibition of [3-H] dopamine release, much higher neuroleptic concentrations were needed to inhibit the electrically stimulated release of other neurotransmitters--[3- H] acetylcholine, [3,H-a1 (gamma-aminobutyric acid).
Abstract: Neuroleptic (antipsychotic) drugs inhibited the electrically stimulated release of [3-H] dopamine from rat striatal slices. The concentrations for 50 percent inhibition (ranging from 11.5 nanomolar for spiroperidol to 800 nanomolar for thioridazine) correlated closely with the average daily dosages of 25 neuroleptic drugs used clinically for schizophrenia. The correlation includes butyrophenones, phenothiazines, reserpine, pimozide, clozapine, and (plus)- butaclamol. Clinically inactive isomers [trans-thiothixene, trans-flupenthixol, and (minus)-butaclamol] required 20 to 1000 times higher concentrations than the active isomers to inhibit release. Compared to the inhibition of [3-H] dopamine release, much higher neuroleptic concentrations were needed to inhibit the electrically stimulated release of other neurotransmitters--[3-H] acetylcholine, [3-H-a1 (gamma-aminobutyric acid). The neuroleptic drugs may block the presynaptic coupling between impulse and neurosecretion.
871 citations
TL;DR: Four chinchillas were trained to respond differently to /t/ and /d/ consonant-vowel syllables produced by four talkers in three vowel contexts, and synthetic stimuli with voice-onset times between 0 and +80 milliseconds were presented for identification.
Abstract: Four chinchillas were trained to respond differently to /t/ and /d/ consonant-vowel syllables produced by four talkers in three vowel contexts. This training generalized to novel instances, including synthetically produced /da/ and /ta/ (voice-on-set times of 0 and +80 milliseconds, respectively). In a second experiment, synthetic stimuli with voice-onset times between 0 and +80 milliseconds were presented for identification. The form of the labeling functions and the "phonetic boundaries" for chinchillas and English-speaking adults were similar.
657 citations
TL;DR: Short-latency evoked potentials recorded from the vertex of adult cats in response to click stimulation were analyzed in a series of lesion experiments to determine the origins of each component.
Abstract: Short-latency evoked potentials recorded from the vertex of adult cats in response to click stimulation (the far-field acoustic response) were analyzed in a series of lesion experiments to determine the origins of each component. The resultant data indicate that the primary generator of potential is the acoustic nerve; of potential 2, the cochlear nucleus; of potential 3, neurons of the superior olivary complex activated by projections crossing the midline; of potential 4, neurons of the ventral nucleus of the lateral lemniscus and preolivary region activated equally by crossed and uncrossed projections; and of potential 5, neurons of the inferior colliculus activated primarily by crossed projections.
TL;DR: Animals and Plants, L. H. Gilbert and P. Raven, Eds.
Abstract: Animals and Plants, L. E. Gilbert and P. H. Raven, Eds. (Univ. ofTexas Press, Austin, 1975), p. 3. 76. J. W. Hanover, Annu Rev. Entomol. 20,75 (1975). 77. R. H. Smith, U.S. For. Serv. Gen. Tech. Rep. PSW-I (1972); A. A. Berryman, BioScience 22, 598 (1972). 78. V. 1. Grimal'skii, L. T. Krushev, V. P. Gorlushkina, Lesn. Khoz. 12, 54 (1971); W. P. Smeljanez and L. A. Chursin, Anz. Schaedlingskd. 45, 33 (1972). 79. C. M. McKell, J. P. Blaisdell, J. R. Goodin, Eds., Wildland Shrubs-Their Biology and Utilization (General Technical Report INT-1, U.S. Forest Service, Washington, D.C., 1972). 80. C. H. A. Little, Can. J. Bot. 48, 1995 (1970). 81. S. J. Dina and L. G. Klikoff, J. Range Manage. 26, 207 (1973); J. D. Hodges and P. L. Lorio, Jr., Can. J. Bot. 47, 1651 (1969); see also Parker (84). 82. D. Otto, Arch. Forstwes. 19, 135 (1970). 83. W. Schwenke, Z. Angew. Entomol. 61, 365 (1968). 84. J. Parker, in Water Deficits and Plant Growth, T. T. Kozlowski, Ed. (Academic Press, New York, 1972), vol. 3, p. 125. 85. A. W. Naylor, in ibid., p. 241; R. E. Saunier, H. M. Hull, J. H. Ehrenreich, Plant Physiol. 43, 401 (1968). 86. T. C. R. White, Oecologia 16,279 (1974). 87. G. T. Harvey, Can. Entomol. 106, 353 (1974); see also Otto (82) and Schwenke (83). 88. T. T. Kozlowski, J. For. 67, 118 (1969); H. 0. Batzer, Environ. Entomol. 2, 727 (1973). 89. D. H. Janzen, Am. Nat. 104, 501 (1970); C. B. Huffaker, in Dynamics of Populations, P. J. denBoer and G. R. Gradwell, Eds. (Centre for Agricultural Publishing and Documentation, Wageningen, Netherlands, 1971), p. 327; J. R. Blais, For. Chron. 44 (1968).
TL;DR: Duffy blood group negative human erythrocytes (FyFy) are resistant to infection by Plasmodium knowlesi, a simian malaria that infects Duffy positive human ERYthrocycles, which suggests that Duffy blood group determinants (Fya or Fyb) may be ery Throcyte receptors for P. vivax.
Abstract: Duffy blood group negative human erythrocytes (FyFy) are resistant to infection by Plasmodium knowlesi, a simian malaria that infects Duffy positive human erythrocytes. The P. knowlesi resistance factor, Duffy negative erythrocytes, occurs in high frequency in West Africa, where the people are resistant to vivax malaria. This suggests that Duffy blood group determinants (Fya or Fyb) may be erythrocyte receptors for P. vivax.
TL;DR: The time course of activity predicted by the model is in good agreement with actual long-term recordings of FTG cells and single-cycle data for LC cells.
Abstract: A model for control of the desynchronized phase of the sleep cycle postulates reciprocal interaction between cells in the pontine gigantocellular tegmental field (FTG cells) and cells in the nucleus locus coeruleus and nucleus subcoeruleus (LC cells). This physiological model leads to equations of the Lotka-Volterra type; the time course of activity predicted by the model is in good agreement with actual long-term recordings of FTG cells and single-cycle data for LC cells.
TL;DR: Viewers briefly glimpsed pictures presented in a sequence at rates up to eight per second and recognized a target picture as accurately and almost as rapidly when they knew only its meaning given by a name.
Abstract: Viewers briefly glimpsed pictures presented in a sequence at rates up to eight per second. They recognized a target picture as accurately and almost as rapidly when they knew only its meaning given by a name (for example, a boat) as when they had seen the picture itself in advance.
TL;DR: Seed biochemical composition was the basis for segregating 24 crops into four distinct groups because sustained seed growth demanded continued nitrogen translocation from vegetative tissues.
Abstract: Seed biochemical composition was the basis for segregating 24 crops into four distinct groups. Nitrogen requirements of pulses and soybeans were so great that sustained seed growth demanded continued nitrogen translocation from vegetative tissues. This translocation must eventually induce senescence in these tissues, restrict the duration of the seed-fill period, and limit seed yield.
TL;DR: It was concluded that introgression from the diversified wild gene pool facilitated the rapid buildup of variation in the domesticated crops and traced the various countermeasures that evolved to ensure fruit set.
Abstract: The article reviews the available information on the start of fruit tree cultivation in the Old World. On the basis of (i) evaluation of the available archeological remains and (ii) examination of the wild relatives of the cultivated crops, it was concluded that olive, grape, date, and fig were the first important horticultural additions to the Mediterranean grain agriculture. They were most likely domesticated in the Near East in protohistoric time (fourth and third millennia B.C.) and they emerge as important food elements in the early Bronze Age. Domestication of all four fruit trees was based on a shift from sexual reproduction (in the wild) to vegetative propagation of clones (under domestication). Olive, grape, date, and fig can be vegetatively propagated by simple techniques (cuttings, basal knobs, suckers) and were thus preadapted for domestication early in the development of agriculture. The shift to clonal propagation placed serious limitations on selection and on fruit set under cultivation. We have examined the consequences of this shift in terms of the genetic makeup of the cultivars and traced the various countermeasures that evolved to ensure fruit set. Finally, it was pointed out that in each of these classic fruit trees we are confronted with a variable complex of genuinely wild types, secondary weedy derivatives and feral plants, and groups of the domesticated clones, which are all interfertile and interconnected by occasional hybridization. It was concluded that introgression from the diversified wild gene pool facilitated the rapid buildup of variation in the domesticated crops.
TL;DR: Although outbreaks (either local or extensive) do reduce plant production temporarily, they commonly occur in individual plants or in whole forest systems that are not particularly productive-that is, those which are under stress resulting from inadequate or excessive moisture, nutrient deficiencies, or pollution, or are senescent, having already passed their peak efficiencies in biomass production.
Abstract: Phytophagous insects are common, ubiquitous elements of most terrestrial ecosystems. Occasionally some species become so abundant that they threaten the stability or output of systems having high ecological, esthetic, or economic value. Forest ecosystems, in particular, support myriads of phytophagous insects, but only few cause dramatic defoliations and widespread destruction of trees. These are termed outbreak species. Four such species currently are stirring public concern in North America: the Douglas fir tussock moth, the gypsy moth, the eastern spruce budworm, and the southern pine bark beetle. Normal insect grazing (from 5 to 30 percent of annual foliage crops) usually does not impair annual plant (primary) production. In fact, it may accelerate growth. Although outbreaks (either local or extensive) do reduce plant production temporarily, they commonly occur in individual plants or in whole forest systems that are not particularly productive-that is, those which are under stress resulting from inadequate or excessive moisture, nutrient deficiencies, or pollution, or are senescent, having already passed their peak efficiencies in biomass production. Moreover, after an outbreak has subsided, there is evidence that the residual vegetation is more productive than the vegetation that was growing immediately before the outbreak. For almost a century, research on phytophagous insects has focused primarily on aspects of their population biology and dynamics and their short-term impact on host plant growth and survival. Only recently has attention been directed at understanding and elucidating their long-term interactions with such fundamental ecosystem processes as primary production and
TL;DR: Examination of aggregate data on graduate admissions to the University of California, Berkeley, for fall 1973 shows a clear but misleading pattern of bias against female applicants.
Abstract: Examination of aggregate data on graduate admissions to the University of California, Berkeley, for fall 1973 shows a clear but misleading pattern of bias against female applicants. Examination of the disaggregated data reveals few decision-making units that show statistically significant departures from expected frequencies of female admissions, and about as many units appear to favor women as to favor men. If the data are properly pooled, taking into account the autonomy of departmental decision making, thus correcting for the tendency of women to apply to graduate departments that are more difficult for applicants of either sex to enter, there is a small but statistically significant bias in favor of women. The graduate departments that are easier to enter tend to be those that require more mathematics in the undergraduate preparatory curriculum. The bias in the aggregated data stems not from any pattern of discrimination on the part of admissions committees, which seem quite fair on the whole, but apparently from prior screening at earlier levels of the educational system. Women are shunted by their socialization and education toward fields of graduate study that are generally more crowded, less productive of completed degrees, and less well funded, and that frequently offer poorer professional employment prospects.
TL;DR: It is hypothesized that the presence of progesterone receptors in human breast tumors may be a sensitive marker for predicting response to endocrine therapy and preliminary clinical correlations show that only those breast tumors with progester one receptors regressed after endocrine Therapy.
Abstract: We hypothesize that the presence of progesterone receptors in human breast tumors may be a sensitive marker for predicting response to endocrine therapy. Progesterone receptors were found in 56 percent of tumors with estrogen receptors, but were absent in tumors without estrogen receptors. Preliminary clinical correlations show that only those breast tumors with progesterone receptors regressed after endocrine therapy.
TL;DR: A role in central mediation of reward perception is suggested for dopamine but not for noradrenaline, after low and high doses of a dopamine blocking agent had effects on lever pressing for intravenous amphetamine reward which resembled the effects of reward reduction and reward termination.
Abstract: Low and high doses of a dopamine blocking agent had effects on lever pressing for intravenous amphetamine reward which resembled the effects of reward reduction and reward termination, respectively. Noradrenaline blockade had no such effects. A role in central mediation of reward perception is suggested for dopamine but not for noradrenaline.
TL;DR: Larviparous female tachinid flies are attracted to taped cricket songs and probably influence male reproductive behavior and sexual competition in these acoustically orienting parasitoids.
Abstract: Larviparous female tachinid flies are attracted to taped cricket songs. In the laboratory flies deposit larvae on a cricket mounted to a speaker; the larvae burrow through the cricket's exoskeleton...
TL;DR: Two integrations of a global general circulation model show that an increase in albedo resulting from a decrease in plant cover causes a decreases in rainfall, which could initiate or perpetuate a drought.
Abstract: Two integrations of a global general circulation model, differing only in the prescribed surface albedo in the Sahara, show that an increase in albedo resulting from a decrease in plant cover causes a decrease in rainfall. Thus any tendency for plant cover to decrease would be reinforced by a decrease in rainfall, and could initiate or perpetuate a drought.
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TL;DR: An elevation in temperature following experimental bacterial infection results in a significant increase in host survival, as measured by survival.
Abstract: The significance of fever in response to a bacterial infection has been investigated using the lizard Dipsosaurus dorsalis as an animal model These lizards develop a fever of about 2 degrees C after injection with the bacterium Aeromonas hydrophila To determine whether this elevation in body temperature increases the resistance of the host to this infection, as measured by survival, lizards were infected with the live bacteria and placed in a neutral (38 degrees C), low (34 degrees or 36 degrees C), or high (40 degrees or 42 degrees C) ambient temperature An elevation in temperature following experimental bacterial infection results in a significant increase in host survival
TL;DR: A sulfur amino acid deficit in the casein diet combined with specific amino acid requirements of the cat appear related to this unique expression of taurine deficiency in cats.
Abstract: A degeneration of the retinal photoreceptor cells develops in cats when casein is the source of dietary protein Amino acid profiles indicate that the degeneration is associated with a selective decrease in plasma and retinal taurine concentrations A sulfur amino acid deficit in the casein diet combined with specific amino acid requirements of the cat appear related to this unique expression of taurine deficiency
TL;DR: Identification of mutant variants of the sequence combined with the in vitro biochemical studies of others has allowed us to tentatively identify the recognition site for each of these proteins, and to suggest how CAP might act at a distance to affect the interaction of RNA polymerase with the promoter.
Abstract: The nucleotide sequence of the lac promoter-operator region has been determined. The 122 base pairs comprising this region include the recognition sites for RNA polymerase, the positive regulatory protein, CAP, and the negative regulatory protein, the repressor. Identification of mutant variants of the sequence combined with the in vitro biochemical studies of others has allowed us to tentatively identify the recognition site for each of these proteins, and to suggest how CAP might act at a distance to affect the interaction of RNA polymerase with the promoter.