Showing papers by "University of California, Davis published in 1976"

Water stress, growth, and osmotic adjustment

Abstract: Many plant processes are affected by mild water stress, with cell growth probably the most sensitive. Except for turgor-mediated processes, the physicochemical basis for the transduction of small changes in water status into alterations in metabolism remains obscure. Turgor pressure is assigned a critical role in cell growth: the physical force needed to sustain enlargement. Simple physical models relating growth to turgor are conceptually useful in examining effects of water stress but can be misleading because metabolic and regulatory responses may be marked and vary temporally. Osmotic adjustment has long been known as a means by which higher plants adapt to salinity, with much of the cell osmotica being ionic and accumulated from the medium. Though not generally recognized, osmotic adjustment also appears to be an important mechanism for adaptation to water-limiting conditions, even in mesophytic plants. In this case much of the osmotica might possibly be internally generated. Recent field data on seasonal and diurnal adjustment and vertical water-potential gradients in plant canopies are discussed relative to growth and water-potential components.

Further Validation of a Psychiatric Symptom Index in a Normal Population

Abstract: A shortened version of the Hopkins Symptom Distress Checklist was constructed for use in a Chicago survey of stress and coping and administered to a cross-section of 2,299 non-patient adults. Labeled the Psychiatric Symptom Index, it measures intensity of 29 different symptoms and allows retrospective self-report of their duration for those respondents reporting high symptoms. This paper reports on the rationale of its construction and on its concurrent validity. For the general adult population the responses to the Index, when factor analyzed, break very clearly into four syndromes: depression, anxiety, anger, cognitive disturbance. Concurrent validity is tested by three criteria: having sought out professional help for emotional problems, having recently used psychoactive drugs, and interviewers' rating respondents' degree of tension. These criteria are significantly related to the Psychiatric Symptom Index and to each of its four syndrome factors.

Sensitive fluorometric method for tissue tocopherol analysis.

Abstract: A sensitive, highly reproducible method for tissue tocopherol analysis that combines saponification in the presence of large amounts of ascorbic acid to remove interfering substances, extraction of the nonsaponifiable lipids with hexane, and fluorometric measurement of the tocopherol is presented. The nonsaponifiable lipid phase contained only one fluorochrome in the 290 nm excitation and 330 nm emission range, and it was identified as tocopherol by thin layer and column chromatography. Column chromatography of the hexane extract of a saponified,14C-tocopherolspiked microsomal fraction showed that no measurable oxidation to tocopherylquinone has occurred. The fluorometric method for tocopherol analysis was applied to homogenates and subcellular fractions from rat liver, kidney, lung, and heart and red blood cells. The heavy mitochondrial and microsomal fractions had the highest subcellular concentrations of tocopherol.

Genetic and biochemical consequences of polyploidy in tragopogon

Abstract: Most studies of the evolution of polyploid plant species have emphasized phylogenetic issues, for example, identification of diploid progenitors and clarification of polyploid complexes. They have largely utilized evidence from comparative morphology, karyotypes and cytogenetic analysis of interploidal hybrids, as well as biochemical profiles of certain classes of compounds such as flavonoids and seed proteins. Although these studies helped greatly to elucidate the mode of origin and ancestry of many polyploid species, they were not concerned with explaining one of the most intriguing features of polyploidy which is that, in many plant genera, the polyploids are more widely distributed over more habitats than their diploid progenitors. This is a problem of the first rank because at least one-third of the Angiosperms and a higher proportion of the ferns are polyploid. Several recent hypotheses have proposed that the wide capabilities of allopolyploids (we use allotetraploids as an example) are a direct biochemical consequence of their possession of two divergent diploid genomes which provides them with a multiplicity of enzymes relative to both diploid parents as well as a high proportion of novel enzymes (Fincham, 1969; Barber, 1970; Manwell and Baker, 1970). Enzyme multiplicity may extend the range of environments in which normal development can take place and, thereby, might account for the frequently wider distribution of polyploids. This may be true even if the tetraploid as a species is less poly-

Pharmacological mechanisms for left ventricular unloading in clinical congestive heart failure. Differential effects of nitroprusside, phentolamine, and nitroglycerin on cardiac function and peripheral circulation.

Abstract: We compared cardiocirculatory actions of the commonly employed systemic vasodilators, intravenous (iv) nitroprusside (NP), iv phentolamine (PH), and sublingual nitroglycerin (NTG), causing left ventricular (LV) unloading in 29 chronic coronary subjects with congestive failure to determine whether they produce disparate responses in LV function by different relaxing actions on systemic resistance and capacitance beds. Each drug equally lowered systemic arterial pressures to a small extent, whereas heart rate rose slightly with NTG. Cardiac catheterization showed a decline in end-diastolic pressure with NTG (19 to 8 mm Hg) which was greater (P less than 0.05) than with NP and PH (21 to 11). Cardiac index increased (P less than 0.05) during NP (2.68 to 2.93 liters/min per m2) and PH (2.60 to 3.02) but was unchanged (2.83) by NTG. Stroke work increased with PH, ejection fraction rose with NP and PH, and mean ejection rate increased with each, whereas pressure-time per minute fell and end-diastolic volume decreased with each agent. Total systemic vascular resistance declined (P less than 0.001) during NP and PH (1,475 to 1,200 dynes sec cm-5) but was unchanged (1,487) by NTG. Plethysmographically, forearm vascular resistance (FVR) decreased (P less than 0.01) with NP and PH (61.6 to 39.1 mm Hg/ml per 100 g/min) but not (52.4) by NTG. The decreases in venous tone (VT) with NTG (18.2 to 9.3 mm Hg/ml) and NP (18.5 to 9.8) were greater (P less than 0.05) than with PH (18.8 to 13.1) FVR/VT percent changes of 0.96, 1.62, and 0.53 with NP, PH, and NTG indicated balanced systemic arteriolovenous relaxation by iv NP, greater arteriolar dilation with iv PH, and predominant venous dilation by sublingual NTG. Thus, vasodilators produce disparate modifications of LV function by their differing alterations of preload and impedance, which are dependent upon relative extents of relaxation of systemic resistance and capacitance vessels characteristic of each agent as used clinically.

Fly ash collected from electrostatic precipitators: microcrystalline structures and the mystery of the spheres.

Abstract: Scanning electron micrographs demonstrate the presence of microcrystalline structures on the surface of coal-derived fly ash samples taken from electrostatic precipitator hoppers. Cenospheres (hollow spheres) were found to be packed with smaller cenospheres, which were also packed with spheres. Microspheres, apparently formed by uneven heating, are encapsulated in the parent sphere. Chemical analyses provide a basis for the postulation of a mechanism of formation for plerospheres (hollow spheres packed with spheres) and microcrystals.

Laplacian-Isoparametric Grid Generation Scheme

Abstract: An alternative to the commonly employed Laplacian grid generation scheme for finite element problems is developed. The procedure is based upon a local quadratic isoparametric transformation. The proposed isoparametric generation scheme overcomes the one serious defect of the commonly used Laplacian scheme, i.e., the inability to significantly utilize boundary curvature information and boundary node point spacing information when locating interior nodes. In addition, a generalized generation scheme is given that includes the Laplacian and isoparametric schemes as special cases of a family of generation schemes; this family is defined by a parameter with a range of zero (Laplacian grid) to one (isoparametric grid). Examples are given which compare grids generated for various values of the parameter.

Characterization of a seventh different subunit of beef heart cytochrome c oxidase. Similarities between the beef heart enzyme and that from other species.

Abstract: Beef heart cytochrome c oxidase has been resolved into seven subunits by electrophoresis in highly cross-linked gels containing urea and sodium dodecyl sulfate. The molecular weights of the polypeptides are estimated to be I, 35 400; II, 24 100; III, 21 000; IV, 16 800; V, 12 400; VI, 8200; and VII, 4400. It has been shown that subunits II and III can coelectrophorese on standard sodium dodecyl sulfate-polyacrylamide gels and appear as a single component with an apparent molecular weight of 22 500. This accounts for previous reports that the beef heart enzyme contains only six subunits. Amino acid analysis of the isolated subunits I, II, and III revealed that they have polarities of 35.5, 44.7, and 39.9%, respectively. All three subunits have an extremely high leucine content and a low percentage of basic amino acids relative to subunits IV-VII. The size, number, and properties of subunits in the beef heart cytochrome c oxidase complex suggest that it has essentially the same subunit structure as the complexes isolated from Saccharomyces cerevisiae and Neurospora crassa.

Oxygen toxicity: augmentation of antioxidant defense mechanisms in rat lung.

Abstract: In studies directed at determining the activities of selected enzymes in lung tissue after in vivo exposure to hyperoxia, 70-day-old rats were exposed to 85% or 90% O2 for 1-14 days. After 7 days of exposure to 90% O2 (1atm), superoxide dismutase activities in mitochondrial and cytosolic fractions increased, respectively, to 245 and 145% of control; glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase activities increased, respectively, to 317, 175, and 413% of control. The levels of reduced glutathione and total nonprotein sulfhydryl compounds were elevated to 195% and 365% of control. Similar changes were observed in rats exposed to 85% O2 for up to 14 days, but to a lesser degree. The changes are interpreted as a reflection of the overall magnitude of oxidant-induced lung injury-reparative processes. The results suggest that hyperoxia induces an increase in lung "antioxidant" defense capabilities. This apparent adaptive response may be important in decreasing the susceptibility of lung tissue to continued O2 toxicity.

Genotypic Responses to Salinity: Differences between Salt-sensitive and Salt-tolerant Genotypes of the Tomato.

Abstract: Four ecotypes of the species Lycopersicon cheesmanii ssp. minor (Hook.) C.H. Mull. from the Galapagos Islands were compared with L. esculentum Mill cv. VF 36 with respect to salt tolerance. The L. cheesmanii ecotype that proved most salt-tolerant was selected for detailed comparison with the L. esculentum cultivar. Plants were grown in modified Hoagland solution salinized with synthetic seawater salt mix. Growth rates under saline conditions were examined and amino acid, sugar, total amino nitrogen, free acidity, and Na and K levels in the tissues of the most and least tolerant plants were measured under salt stress and nonstress conditions. Results indicate that all Galapagos ecotypes were far more salt-tolerant than was the esculentum cultivar. They could survive in full strength seawater nutrient solution while the esculentum cultivar could not in most cases withstand levels higher than 50% seawater. Growth rates were reduced in both species under saline conditions but the esculentum cultivar was more severely affected. High levels of total amino nitrogen, specific amino acids, and free acidity along with low sodium content were found in the salt stressed VF 36 cultivar. The opposite responses were noted in the salt stressed treatments of the Galapagos ecotype. Tissue sugar levels did not appear to be similarly correlated with salt stress in either species. Potassium content fell sharply during salinization in the Galapagos ecotype while in the esculentum cultivar it declined relatively little even at high levels of salinity.

Nitrate Absorption by Barley I. Kinetics and Energetics

Abstract: The absorption of NO3− by barley (Hordeum vulgare L) was investigated by following the disappearance of NO3− The absorption was related to several parameters: NO3− and Ca2+ concentrations, pH, and the presence of various anions Absorption rate increased with increasing Ca2+ concentration, reaching a maximum at approximately 5 mm Ca2+, and was considerably inhibited by NH4+ Absorption was influenced markedly by pH, and little or not at all by anions (Cl−, Br−, SO42−), and was decreased by respiratory and oxidative phosphorylation inhibitors

Inhibition of ethylene production by cobaltous ion.

Abstract: The effect of Co(2+) on ethylene production by mung bean (Phaseolus aureus Roxb.) and by apple tissues was studied. Co(2+), depending on concentrations applied, effectively inhibited ethylene production by both tissues. It also strongly inhibited the ethylene production induced by IAA, kinetin, IAA plus kinetin, Ca(2+), kinetin plus Ca(2+), or Cu(2+) treatments in mung bean hypocotyl segments. While Co(2+) greatly inhibited ethylene production, it had little effect on the respiration of apple tissue, indicating that Co(2+) does not exert its inhibitory effect as a general metabolic inhibitor. Ni(2+), which belongs to the same group as Co(2+) in the periodic table, also markedly curtailed both the basal and the induced ethylene production by apple and mung bean hypocotyl tissues.In a system in which kinetin and Ca(2+) were applied together, kinetin greatly enhanced Ca(2+) uptake, thus enhancing ethylene production. Co(2+), however, slightly inhibited the uptake of Ca(2+) but appreciably inhibited ethylene production, either in the presence or in the absence of kinetin. Tracer experiments using apple tissue indicated that Co(2+) strongly inhibited the in vivo conversion of l-[U-(14)C]methionine to (14)C-ethylene. These data suggest that Co(2+) inhibited ethylene production by inhibiting the conversion of methionine to ethylene, a common step which is required for ethylene formation by higher plants.Co(2+) is known to promote elongation, leaf expansion, and hook opening in excised plant parts in response to applied auxins or cytokinins. Since ethylene is known to inhibit these growth phenomena, it is suggested that Co(2+) exerts its promotive effect, at least in part, by inhibiting ethylene formation.

Discarded appendicularian houses as sources of food, surface habitats, and particulate organic matter in planktonic environments

Abstract: Observations using SCUBA reveal that macroscopic organic aggregates produced by appendicularians reached densities of 44 to 1,130 m-’ in the Gulf of California. Though these aggregates constituted less than 5% of total particulate carbon, their carbon : nitrogen ratio was twice that of particles in the surrounding seawater. The C : N ratio of the total particulate matter increased directly with the density of appendicularian produced aggregates. Aggregates were utilized extensively as food by euphausiid larvae, copepods, and planktivorous fish. Such aggregates affect the adaptive strategies and distribution of the plankton by introducing spatial heterogeneity and physical structure into an environment previously considered unstructured and may substantially alter the chemical composition of particulate organic matter, Little is known of the role of planktonic organisms in forming particulate organic matter in the sea. Many zooplankton, cspecially pteropods ( Gilmcr 1972)) gastropod and annclid larvae ( Hamner et al. 1975)) salps ( Madin 1974), and appendicularians (Alldredge 1972) product macroscopic, mucus aggregates ranging from a few millimeters to 2 m in diameter. Since the fragility, size, and patchy distribution of these macroscopic aggregates makes them difficult to sample using standard ship-board tcchniqucs, little is known of their ecology. Yet macroscopic aggregates may be disproportionately important to the pelagic community as sources of food (Parsons and Strickland 1962; Alldrcdge 1972)) surface microhabitats ( Pomeroy and Johanncs 1968), and as components potentially affecting the chemical composition of total particulate organic matter (Riley 1970). Appendicularians, or larvaccans, are pelagic tunicates which filter particles through the “house,” a unique feeding structure secreted around the animal by glandular epithelium on the body. When the external filters become clogged with phytoplankton or particulate matter, the house is discarded but remains in the water column as a recognizable organic aggregate. A single animal ’ Present address: Department of Biological Sciences, University of California, Santa Barbara 93106. may build and discard six houses per day ( Lohmann 1909). The following study describes the abundance, organic composition, and significance of macroscopic aggregates produced by appcndicularians as an example of the possible impact of mucusproducing zooplankton on particulate organic matter and trophic relationships in the sea. I thank R. Laskcr and R. W. Eppley for the USC of their CHN analyzers and E. Brinton, M. Knight, A. Flemingcr, and R. Bauer for aid with identification of crustaceans. I am grateful to M. M. Mullin and P. J, Richerson for critical review of the manuscript and especially to W. M. Hamner for many helpful suggestions throughout this study. Materials and methods Field data were collected at depths of 5 to 25 m in the Florida Current lo-15 km west of Bimini throughout 1971-1972 and in the Gulf of California 2-5 km east of Puerto Escondido during July and August 1973 and 1974. Conventional SCUBA techniques modified for open-ocean research diving (IIamncr 1975) were used. I collected three catcgorics of field data: visual dctermina tion of appendicularian and discarded house densities; hand collection of animals and houses; hand collection of water samples for chemical analysis. LIMNOLOGY AND OCEANOGRAPHY 14 JANUARY 1976, V. 21(l) Discarded appendicularian houses 15 The size and shape of the incurrent and feeding filters permitted specific idcntification of discarded appendicularian houses. I counted appcndicularians and houses visually using a handheld grid 10 X 20 X 20 cm ( l/250 rn” ) made of Plexiglas rod. I was tied to a central pivot by a cord and swam in a large arc, stopping every two kicks to count the contents of the grid. The occurrence of zooplankton on discarded houses, the number of houses damaged by foraminifera and Trichodesmium ( a blucgreen alga), and the number of occupied houses wcrc noted, Data were recorded on an underwater tape recorder equipped with a throat microphone. I measured house diameters from enlargcd photographs of occupied houses taken while diving ( Alldredgc 1972). IIouse volumes were calculated assuming the houses to be spheres. (The torpcdoshaped house of Megalocercus huxleyi was assumed to bc a cylinder. ) Houses were collected by hand in individual collecting jars to determine the contribution of discarded appendicularian houses to total particulate carbon and nitrogcn in seawater. Random collection was assured by taking the first 15-30 houses I encountered regardless of size or species. Discarded houses identifiable to species were also collcctcd for laboratory analysis. Replicate water samples were collected by hand for analysis of total particulate carbon and nitrogen, simultaneously with the visual counts and house collections, in a clean S-liter, collapsible polyethylene “cubctainer.” Care was taken to exclude appcndicularian houses from thcsc samples. The accuracy of direct visual counting of these small organisms by SCUBA divers was determined through a program of simultaneous net tows and visual counts. While the population density of appendicularians was being determined visually at 10 to 15 m, a calibrated Clarke-Rumpus net of 0.15-mm mesh size was simultaneously towed in a 200-400-m-diameter circle around the diver.

Fog basking by the Namib Desert beetle, Onymacris unguicularis

Abstract: THE Namib Desert along the south-western coast of Africa supports a sand dune fauna without counterpart elsewhere in the world1. The trophic base of the arthropod fauna is wind-blown detritus2. Aperiodic advective fog collection from vegetation3 or detritus4 is a possible source of water for diverse Namib animals. For the specialised fauna living in vegetation-less dunes, fog collection from detritus4, disturbed sand projections5, directly from humid air6, or from water precipitated on the body4,7, seem to be the only possible water uptake methods. Water uptake from saturated or subsaturated air, demonstrated for a few arthropod species6, is not a physiological capability of Namib tenebrionids already investigated4,6,7.

The effective interaction between nucleons deduced from nuclear spectra

Abstract: Two-body matrix elements of the residual nucleon-nucleon interaction are extracted from experimental data throughout the periodic table and are used to determine the ranges and well depths of various components of a local interaction. The $T=1$ even and odd components of the central interaction both definitely require two wells with different ranges; a shorter-range attractive well with a longer-range repulsive one. The need for a tensor interaction and a two-body spin-orbit interaction is also explored and their inclusion improves the fit slightly.

Isolation and characterization of X-linked mutants of Drosophila melanogaster which are sensitive to mutagens.

Abstract: Thirteen X-linked mutants have been isolated in Drosophila melnnogaster which render male and homozygous female larvae sensitive to the mutagen methyl methanesulfonate. Their characterization and preliminary assignment to functional groups is described. Four of these mutants are alleles of mei-41 (BAKER and CARPENTER 1972). Like previously isolated alleles of this locus, these mutants reduce fertility and increase loss and nondisjunction of the Xchromosome in homozygous females. The remaining mutants have been tentatively assigned to six functional groups (two mutants to the mus(1)lOl locus, two to mus(l)l02, two to mus(l)l03, and one each to mus(I)l04, “(1)105, and mus(l)l06). Several of the complementation groups can be distinguished on the basis of nondisjunction and cross sensitivity to mutagens. Females homozygous for the mei-41, mus(1)lOl and mus(l)l02 mutants exhibit elevated levels of nondisjunction. Mutants belonging to complementation groups mei-41, mus(l)lOl, and mus(l)l04 are sensitive to nitrogen mustard (HN2) in addition to their MMS sensitivity. Among these mutants there is currently a direct correlation between sensitivity to HN2, sensitivity to 2acetylaminofluorene and a deficiency in post-replication repair (BOYD and SETLOW 1976). Only the mei-41 mutants are hypersensitive to UV radiation, although several of the mutants exhibit sensitivity to y-rays. Semidominance is observed in female larvae of the mei-41, mus(l)l04, and mus(l)l03 mutants after exposure to high concentrations of MMS. The properties of the mutants generally conform to a pattern which has been established for related mutants in yeast. Additional properties of these mutants are summarized in Table 9. INTENSIVE studies of DNA repair in prokaryotes have revealed the existence of a complex array of mechanisms which are capable of reversing a variety of alterations in the genetic material (see review volumes edited by HANAWALT and SETLOW 1975). Because of the complexity and redundancy associated with these systems, the isolation of repair-deficient mutants has been of paramount importance in defining the various repair pathways and their interrelationships. Parallel genetic studies in fungi have extended this area into the realm of simple eukaryotes (see review by CATCHESIDE 1974). At the alternate end of the eukaryotic spectrum studies of human genetic disorders have provided definitive evidence for the existence of several different repair mechanisms in complex Studies of radiation sensitivity are taken from the Ph D. thesis of T. D NGUYEN.

THE mei-9a MUTANT OF DROSOPHILA MELANOGASTER INCREASES MUTAGEN SENSITIVITY AND DECREASES EXCISION REPAIR

Abstract: The mei-9a mutant of Drosophila melanogaster , which reduces meiotic recombination in females (Baker and Carpenter 1972), is deficient in the excision of UV-induced pyrimidine dimers in both sexes. Assays were performed in primary cultures and established cell lines derived from embryos. An endonuclease preparation from M. luteus , which is specific for pyrimidine dimers, was employed to monitor UV-induced dimers in cellular DNA. The rate of disappearance of endonuclease-sensitive sites from DNA of control cells is 10–20 times faster than that from mei-9a cells. The mutant mei-218, which is also deficient in meiotic recombination, removes nuclease-sensitive sites at control rates. The mei-9a cells exhibit control levels of photorepair, postreplication repair and repair of single strand breaks. In mei-9 cells DNA synthesis and possibly postreplication repair are weakly sensitive to caffeine. Larvae which are hemizygous for either of the two mutants that define the mei-9 locus are hypersensitive to killing by the mutagens methyl methanesulfonate, nitrogen mustard and 2-acetylaminofluorene. Larvae hemizygous for the mei-218 mutant are insensitive to each of these reagents. These data demonstrate that the mei-9 locus is active in DNA repair of somatic cells. Thus functions involved in meiotic recombination are also active in DNA repair in this higher eukaryote. The results are consistent with the earlier suggestions (Baker and Carpenter 1972; Carpenter and Sandler 1974) that the mei-9 locus functions in the exchange events of meiosis. The mei-218 mutation behaves differently in genetic tests and our data suggest its function may be restricted to meiosis. These studies demonstrate that currently recognized modes of DNA repair can be efficiently detected in primary cell cultures derived from Drosophila embryos.

Surface Area Reduction During Isothermal Sintering

Abstract: A kinetic model for the reduction in specific surface area during isothermal sintering is examined in detail. Experimental data for a variety of materials including A12O3, B, Ni, Cu, ZnO, TiO2, Fe2O3, and As-Se-S glasses are analyzed by the technique provided. The results of this technique agree well with those for previously identified sintering mechanisms for each material. The kinetic model is based on sintering driven by the curvature gradient in the interparticle neck region associated with initial-stage sintering. At the intermediate stage of sintering, a diminished curvature gradient shifts the sintering driving force to the excess surface free energy.

Study of genetic relationships among marine species of the genera Beneckea and Photobacterium by means of in vitro DNA/DNA hybridization.

Abstract: Strains representative of species of the marine genera Beneckea and Photobacterium were used as reference standards in in vitro DNA/DNA competition experiments. Within a given species, strains were found to be related by over 80% competition. (Competition was defined as the amount of radioactive DNA displaced by heterologous DNA relative to the amount displaced by homologous DNA.) On the basis of interspecies competition values (expressed as averages), the following groupings could be made: 1. "Photobacterium" fischeri was related to strain ATCC 15382 by a competition of 38% and was distinct from all the other strains tested (competition less than or equal to 11%). 2. The genus Photobacterium consisted of 3 species, P.phosphoreum, P.leiognathi, and a newly designated species, P.angustum (composed of non-luminous strains). The latter species was found to be related to P.leiognathi and P.phosphoreum by 56 and 28% competition, respectively, while P.phosphoreum was related to P.leiognathi by 29%. 3. In the genus Beneckea, 65% competition was detected between B.harveyi and B.campbellii as well as between B.parahaemolytica and B.alginolytica. These pairs of species were related to each other by 51-58% and to B.natriegens by 34-56% competition. A newly designated pathogenic species, B.vulnifica, appeared to have a low but significant relationship to all the above mentioned species of Beneckea. 4. Two biotypes, related by 68% competition, were recognized in the species B.splendida. Similarly, B.pelagia was found to consist of 2 biotypes related by a competition of 67%. The competition values between these species were 38-40%. 5. B.nereida, B.nigrapulchrituda, and "Vibrio" anguillarum had competition values less than or equal to 30% to each other as well as to other species of Beneckea. 6. With Vibrio cholerae as the reference standard, V.albensis was found to be related by a competition of 82%, while V.proteus and V.metschnikovii had competition values of 22 and 12%, respectively. These results suggested that V.albensis should be synonymized with V.cholerae, while the latter two organisms should remain distinct from this species. V.cholerae as well as the other terrestrial organisms tested did not appear to be significantly related to any of the marine strains (competition values less than or equal to 27%). The speciation derived from the results of the DNA/DNA competition experiments was compared to previous speciation based on phenotypic similarities.

Growth, development and composition of the udder and gravid uterus of beef heifers during pregnancy.

Abstract: Forty-six Hereford heifers were slaughtered at different stages of gestation. Udders and gravid uteri were removed. Each gravid uterus was dissected into fetus, fetal membranes, fetal fluids and uterus. Fresh weights, dry matter, ether extract, ash, nitrogen and gross energy contents of the various tissues were determined. Weights and compositions of udders and uteri from 36 non-pregnant heifers were also determined. Relationships of the type W = Woe (b~-b2t) t where t is the number of days after mating, Wo is the amount of constituent on the day of mating and W is the amount of constituent on day t of gestation were derived to describe growth of different constituents of the gravid uterus during gestation. Udder development was most rapid after 234 days of gestation as indicated by ash and nitrogen contents. Udders of pregnant heifers contained approximately 48, 60, 67 and 102 g nitrogen at 134, 189, 237 and 264 days of gestation, respectively and udders of non-pregnant heifers contained approximately 37 g nitrogen. No net accumulation of energy occurred in udders of pregnant heifers re/ative to that gained in udders of non-pregnant heifers. Fetuses averaged 1.58, 7.53, 20.8 and 31.6 kg and contained 1.20, 1.60, 2.07 and 2.52% nitrogen at 134, 189, 237 and 264 days of gestation, respectively. Gross energy contents of fetuses were .54, .88, 1.17 and 1.32 kcal/g fresh weight at each of these times. Rates of nitrogen and energy storage in the gravid uterus were estimated to be .76, 2.79, 8.95 and 25.0 g/day and 36.0, 143,457 and 1,167 kcal/day at 100, 160, 220 and 280 days of gestation, respectively. None of these values was affected by fetal sex or maternal energy intake (150 or

Finite Element Model for Cohesive Sediment Transport

Abstract: A mathematical model that simulates erosion, transport and deposition of cohesive sediments in a two-dimensional flow field is presented The governing equations are solved by the finite element method using the Galerkin formulation The domain is subdivided into a series of triangular elements in which a quadratic approximation is made for the suspended sediment concentration Expressions used for the rate and conditions under which erosion and deposition occur are from previous experimental studies Continuing aggregation is accounted for by specifying the settling velocity of the flocs in each element The model is verified by comparison with analytic solutions and the results of a flume test