Bryologische Fragmente

Ohne Zusammenfassung     

Effects of dehydroepiandrosterone on obesity and glucose-6-phosphate dehydrogenase activity in the lethal yellow mouse (strain 129/Sv-Ay/Aw)

We investigated the anti-obesity effects of the adrenal androgen, dehydroepiandrosterone (DHEA), on genetically predisposed obese lethal yellow mice (Ay/Aw). Secondly, we tested the hypothesis that DHEA promotes its anti-obesity effects by decreasing the activity of glucose-6-phosphate dehydrogenase (G6PDH). We subjected four genotype-sex combinations of yellow and agouti (control) mice to four dietary treatments and determined weight changes, food consumption, and G6PDH activity. Although G6PDH activities of yellow mice were considerably decreased in the 0.4% DHEA treatment group, they were elevated in the 0.0 and 0.1% DHEA treatment groups. In contrast, G6PDH activities of DHEA-treated control agouti mice remained relatively constant. These studies confirm that DHEA prevents the Ay gene from promoting excess fat deposition via some mechanism(s) other than reduced dietary intake. However, the overall absence of agreement between weight change (gain or loss) and G6PDH activity suggests that the anti-obesity activity of DHEA is not mediated via G6PDH. Since yellow obese (Ay/Aw) mice were found to be more susceptible to DHEA's effects than their agouti (Aw/Aw) littermates, Ay appears to induce an altered metabolism in Ay/Aw mice which is more susceptible to the effects of DHEA than the normal metabolism of Aw/Aw mice.     

Differentiation of hairbulb pigment cell melanosomes in compound agouti and albino locus mouse mutants (Ay, a, c2J; C57BL/6J)

Our objective was to determine using electron microscopy how nonagouti (a), lethal yellow (Ay), and albino (c2J) genes affect the program of mouse hairbulb melanosome differentiation; 1,921 hairbulb melanosomes from four genotypes (a/a C/C = B,Ay/a C/C = Y, a/a c2J/c2J = BA, and Ay/a c2J/c2J = YA) were scored for developmental stage, length, and width. Qualitative and quantitative electron microscopy revealed the following. An albino locus-induced diminution of melanosome size suggests that the albino locus is involved in structural features of melanosomes not directly related to the synthesis and deployment of tyrosinase. Ratio data on melanosome length-to-width confirm that the agouti locus determines melanosome shape, either spherical or elliptical; melanization is not required for melanosomes to achieve their agouti-locus-determined shapes. YA (Ay/a c2J/c2J) melanosomes, characterized by poorly organized matrices, absence of active tyrosinase, unusually large membrane invaginations, and significantly smaller dimensions than those of BA (a/a c2J/c2J), showed additive effects of both Ay and c2J alleles. These data suggest that the albino locus plays a structural as well as functional (tyrosinase) role in the differentiation of mouse hairbulb melanosomes. The agouti locus, even in the absence of melanization, directs melanosome shape either via synthesis and deployment of agouti-locus-encoded matrix proteins or by other structural factors. The additive effects of Ay and c2J alleles in compound YA mutants document the importance of specific interactions both functional and structural between agouti and albino loci.     

Attempt to detect recombination between B-F and B-L genes within the chicken B complex by serological typing,in vitro MLR,and RFLP analyses

In search for recombinants within the chicken major histocompatibility B complex, 1155 animals from crosses between the congenic lines CB (B¹²) and CC (B⁴) were tested with alloantibodies and monoclonal antibodies for the B-F (class I), B-L (class II), and B-G (class IV) antigens and by mixed lymphocyte reaction. The absence of detectable recombination was confirmed by restriction fragment length polymorphism analysis with B-L and B-F probes. Together with previous reports, this indicates that the distance between the B-F and B-L loci is below 0.01 centimorgan.     

Physiological control and process kinetics of clavine alkaloid production byClaviceps purpurea

Summary Kinetic parameters of production of clavine alkaloids were evaluated in twoClaviceps purpurea strains. Mutagenesis brought about enhanced resistance of the biosynthetic system towards alkaloids. Addition of glucose into the fermentation medium altered the zero order kinetics of production to activation-inhibition kinetics. The glucose treatment allowed performance of both elymoclavine-inhibitionless and clavine alkaloid-decompositionless fermentations if a combination of fermentation and separation units in a closed loop was used.Nomenlacture k ₁ rate constant of agroclavine synthesis (mg Agro · mg Elymo/l·g DW·day for stage 1, mg Agro/g DW·day for stage 2) - k ₂ parameter describing inhibition of agroclavine formation rate by elymoclavine (mg Elymo/l) - k ₃ specific rate of agroclavine decay (l/g DW·day) - k ₄ maximal specific rate of elymoclavine synthesis (stage 1, 1/g DW·day, stage 2, mg Elymo/g DW·day) - k ₄ ^– maximal specific rate of elymoclavine synthesis in stage 1 (inhibition-activation mechanism) (mg Elymo/g DW·day) - k ₅ physiological constant describing the elymoclavine decay rate (l²/g DW·day·mg Elymo) - k ₅ ^– physiological constant describing the activation of elymoclavine biosynthesis by elymoclavine (mg Elymo/l) - k ₆ physiological constant describing the repression of elymoclavine biosynthesis by elymoclavine (mg Elymo/l) - k ₇ maximal specific growth rate (1/day) - k ₈ specific rate of biomass decay (l/g DW·day) - A agroclavine concentration (mg/l) - E elymoclavine concentration (mg/l) - r _A specific rate of agroclavine biosynthesis (mg Agro/g DW·day) - r _E specific rate of elymoclavine biosynthesis (mg Elymo/g DW·day) - r _i specific rate of alkaloid biosynthesis (mg alkaloid/g DW·day) - X dry biomass concentration (g/l) - specific growth rate (1/day) Abbreviations Agro agroclavine - Elymo elymoclavine - Chano chanoclavine - DW dry weight of biomass     

Voluntary progression order in captive rhesus macaques

The sequence in which 14 laboratory rhesus macaques left their home enclosure during a routine catching procedure was recorded on 30 occasions during 6 weeks. The animals were trained to voluntarily exit one by one and enter a transport cage for weighing and/or treatment. Mean weekly exit orders cross-correlated significantly, and individuals retained their exit positions with remarkable consistency throughout the study period. An animal's position did not depend on its sex, age, or dominance rank. The oldest female never failed to enter the transport cage as number 1. When she was prevented from taking the lead, the group was hesitant but eventually proceeded in the usual order. Food was a strong, yet not absolute, incentive for the monkeys to cooperate. If they could not expect a reward, they took more time before proceeding, but did so in the habitual order. The predictability of the exit sequence has practical managerial value because it makes it possible for a single person to quickly catch a selected group member when necessary.     

Immunohistochemical localization of porcine diazepam-binding inhibitor (DBI) to rat endocrine pancreas

Summary The occurrence of diazepam-binding inhibitor (DBI), isolated and characterized from porcine upper intestine, was examined in the pancreas of Sprague-Dawley albino rats using indirect immunofluorescence. The polypeptide was found in the endocrine Langerhans islets and, utilizing double-labelling controls, it was shown to be present within the peripherally located glucagon-containing cells. Regulation of islet hormone production may therefore be under DBI control.     

Courtship behavior among musk-ox males kept in confinement

During twelve 2-h observation sessions courtship behavior was recorded among seven musk-ox males (Ovibos moschatus) kept in a paddock together with six females. The animals were sexually mature and of the same age. Foreleg kicking and genital sniffing were more common than mounting. All three activities were of a nonaggressive nature but were shown almost exclusively by dominants toward subordinate partners. Assuming the role of courted females, recipients were never the target of aggressive acts. It was concluded that courtship among mature musk-ox males functions as a nonaggressive reinforcement of dominance, promoting low-risk coexistence of males.     

Hypervariability of intronic simple (gt)n(ga)m repeats in HLA-DRB genes

We have investigated the extent of DNA variability in intronic simple (gt)_n(ga)_m repeat sequences and correlated this to sequence polymorphisms in the flanking exon 2 of HLA-DRB genes. The polymerase chain reaction (PCR) was used to amplify a DNA fragment containing exon 2 and the repeat region of intron 2. The PCR products were separated on sequencing gels in order to demonstrate length hypervariability of the (gt)_n(ga)_m repeats. In a parallel experiment, the PCR products were cloned and sequenced (each exon 2 plus adjacent simple repeats) to characterize the simple repeats in relation to the HLA-DRB sequences. In a panel of 25 DRB1, DRB4, and DRB5 alleles new sequences were not detected. Restriction fragment length polymorphism (RFLP) subtyping of serologically defined haplotypes corresponds to translated DNA sequences in 85% of the cases, the exceptions involving unusual DR/DQ combinations. Many identical DRB1 alleles can be distinguished on the basis of their adjacent simple repeats. We found group-specific organization of the repeats: the DRw52 supergroup repeats differ from those of DRB1*0101, DRB4*0101, and DRB5*0101 alleles and from those of pseudogenes. Finally, we amplified baboon DNA and found a DRB allele with extensive similarity to DRB1 sequences of the DRw52 supergroup. The simple repeat of the baboon gene, however, resembles that of human pseudogenes. In addition to further subtyping, the parallel study of polymorphic protein and hypervariable DNA alleles may allow conclusions to be drawn on the relationships between the DRB genes and perhaps also on the theory of trans-species evolution.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number M 34258.