Thermal biology of the common garter snake Thamnophis sirtalis (L.)

Summary The thermoregulatory significance of a striped-melanic colour polymorphism in the common garter snake, Thamnophis sirtalis, was assessed through a combination of labortory experimentation and field study. In experiments with living snakes the melanic morph maintained a higher body temperature than the striped morph, when exposed to natural insolation. Experiments with excised skin showed that this thermal advantage is attributable to some integumental difference between the two morphs. Body temperatures of snakes in the field revealed that, during the colder part of the active season, melanics were able to stay warmer than striped snakes by an amount (1.24 C°) approximating the difference observed in the laboratory. Some evidence and argument is presented to suggest that melanism also may confer protection against overheating in warm periods.     

Reduction and azo coupling of quinones

Summary Cutaneous melanin in formol fixed skin and adrenochrome in dichromate fixed monkey adrenal after adequate bisulfite or dithonite reduction were found to give definite azo coupling reactions. Weaker reactions were obtained on unreduced material, and these disappeared on ferric chloride oxidation. Both cutaneous melanin and adrenochrome appear to exist in a quinhydrone status. Prolongation of dichromate treatment weakens or abolishes azo coupling capacity of adrenochrome. The findings support the concept of quinonization and reduction to prevent and restore azo coupling of enterochromaffin cells and noradrenaline islets of the adrenal.The most effective diazos for melanin werep-nitrodiazobenzene, fast black K and the diazosulfanilic acid, pH 1 pyronin B procedure, for adrenochrome. Diazosafranin and 2-chloro-4-nitrodiazobenzene were also useful. Blue and violet coupling products from toluidine blue and methylene violet RR fail to yield sufficient contrast to be convincing.     

Inferences about the conformation of somatostatin at a biologic receptor based on NMR studies

Examination of two diastereomeric analogs of somatostatin differing in stereochemistry at the tryptophan residue has revealed a high field resonance in the -Trp isomer which is assigned to the γ-methylene of Lys⁹. The extent of correlation of this shift with biologic activity for a series of analogs of somatostatin is discussed. From comparison of close analogs, it is suggested that the biologically active conformation of somatostatin at the receptor controlling insulin release is not the major conformation of this hormone in solution. It is suggested that the conformation of somatostatin at this receptor resembles more closely the solution conformation of analogs having tryptophan in the -configuration. This latter conformation places the Trp⁸-Lys⁹ side chains in close proximity, thus shifting the γ-methylene protons of Lys⁹ upfield.     

The alleles of theH-13 locus

Seven congenic strains differing from C57BL/10Sn at theH-13 locus have been produced which define fourH-13 alleles. Isografting, exchanging of grafts between sublines, F(1) testing, and linkage testing demonstrate the presence of additionalH genes in four of these strains. The medial survival times (MSTs) of skin grafts fromH-13(a) to unimmunizedH-13(b) recipients ranged from 69 to 83 days. Rejection across all other barriers was extremely weak with most MSTs being > 100 days. Preinjection of donor strain thymocytes caused accelerated rejection of skin grafts fromH-13(a) toH-13(b) mice, but had only minimal effect on skin grafts across other barriers. Rejection ofH-13 incompatible grafts was significantly stronger when the donor and host areH-3(a) than when they wereH-3(b).     

Origin of mitochondrial enzymes. V. The polypeptide character and the biosynthesis of rat liver cytochromec oxidase polypeptides by mitochondria

Isolated rat liver mitochondria were labeled in vitro withl-[¹⁴C]leucine. Sixty percent of the incorporated radioactivity was found to reside in subunits 1, 2, and 3 of cytochromec oxidase with apparent molecular weights of approximately 33,000, 25,000, and 20,000, respectively. The results indicate that these are the predominant products of protein synthesis under the conditions employed. The enzyme complex, as derived by immunoprecipitation, was found to contain four additional polypeptides with apparent molecular weights of 17,000, 12,500, 7000, and 3500. A comparison of electrophoretic profiles of the rat liver and beef heart enzyme reveals that the apparent molecular weights of all polypeptides are remarkably similar.To be submitted as partial fulfillment of the requirements for the Ph.D. degree of this institution.     

Isolation of Marine Bacteria Capable of Producing Specific Lyases for Alginate Degradation

Alginate lyases (EC 4.2.2.3) were isolated from cultures of several marine bacterial isolates. The lyases were induced by native alginate and had activity toward both the mannuronic acid and the guluronic acid blocks of the alginate polymer. The guluronic acid-specific lyase was recovered from the medium, whereas the mannuronic acid-specific lyase was retained with the bacteria.     

Presence of coenzyme M derivatives in the prosthetic group (coenzyme MF430) of methylcoenzyme M reductase from Methanobacterium thermoautotrophicum

2-Mercaptoethanesulfonic acid (coenzyme M), or a derivative of it, and a yellow chromophore, known as the nickel-containing tetrapyrrole factor F₄₃₀, occur in the prosthetic group of methylcoenzyme M reductase in an equimolar amount, and bound to each other; this enzyme catalyzes the final step of methane production. The prosthetic group, which is called coenzyme MF₄₃₀, was isolated from the purified enzyme and was extracted from cells. The presence of coenzyme M was confirmed by a bioassay using Methanobrevibacter ruminantium and by the use of chemical and physicochemical analyses.     

Brain endocast asymmetry in pongids and hominids: Some preliminary findings on the paleontology of cerebral dominance

Observations on petalial asymmetry for 190 hominoid endocasts are reported, and their statistical differences assessed. While all taxa of hominoids show asymmetries to various degrees, the patterns or combinations of petalial asymmetries are very different, with fossil hominids and modern Homo sapiens showing an identical pattern of left-occipital, right-frontal petalias, which contrasts with those found normally in pongids. Of the pongids, Gorilla shows the greater degree of asymmetry in left-occipital petalias. Only modern Homo and hominids (Australopithecus, Homo erectus, Neandertals) show a distinct left-occipital, right-frontal petalial pattern. Analysis by x² statistics shows the differences to be highly significant. Due to small sample size and incompleteness of endocasts, small-brained hominids, i.e., Australopithecus, are problematical. To the degree that gross petalial patterns are correlated with cognitive task specialization, we speculate that human cognitive patterns evolved early in hominid evolution and were related to selection pressures operating on both symbolic and spatiovisual integration, and that these faculties are corroborated in the archaeological record.     

A remnant New Zealand carr

Carr vegetation was once extensive in New Zealand. It can be divided into Cordyline australis I Carex secta carr, comprising an open wood with scattered large herbs and an abundance of Carex species, and podocarp carr, dominated by tall conifers. Both have been almost eliminated by agricultural development. We studied a remnant of Cordyline australis I Carex secta carr in South Island, which graded at one end into salt marsh. Eight communities were recognized, including one pure salt marsh and two more with saline influence. Near the stream that provided moisture and alluvium for the area were herbaceous communities. In the poorly-drained area away from the stream were communities dominated by shrubs and small trees. The soil environment is similar to that of many European carrs, though generally less organic. A number of the exotic species are also found in European carrs.