Morphology of the facets of the proximal Tarsi bones from an ancient population

The analysis of morphological variation of tali and calcanei articular surfaces from “S'Illot des Porros” (Majorca, 2430±200 BP) has been made. It indicates the high frequency of extensions of the talocrural and subtalar surfaces, which are shown to be produced not only by a high level of stress on the bones. The presence of the sulcus tali facet in most cases could indicate, however, a greater degree of lateral movement of the foot.     

Evaluation of automated analysis of 15N and total N in plant material and soil

Simultaneous determination of ¹⁵N and total N using an automated nitrogen analyser interfaced to a continuous-flow isotope ratio mass spectrometer (ANA-MS method) was evaluated. The coefficient of variation (CV) of repeated analyses of homogeneous standards and samples at natural abundance was lower than 0.1%. The CV of repeated analyses of ¹⁵N-labelled plant material and soil samples varied between 0.3% and 1.1%. The reproductibility of repeated total N analyses using the automated method was comparable to results obtained with a semi-micro Kjeldahl procedure. However, the automated method gave results which were 3% to 5% higher than those obtained with the Kjeldahl procedure. Since only small samples can be analysed, careful sample homogenization and fine grinding are very important. Evaluation of a diffusion method for preparing nitrate and ammonium in solution for automated ¹⁵N analysis showed that the recovery of inorganic N in the NH₃ trap was lower when the N was diffused from water than from 2 M KCl. The results also indicated that different proportions of the NO₃ ^- and the NH₄ ⁺ in aqueous solution were recovered in the trap after combined diffusion. The method is most suited for diffusing either NO₃ ^- or NH₄ ⁺ alone, but can be used for combined diffusion of the two ions.     

A supernumerary “B-sex” chromosome drives male sex determination in the Pachón cavefish,Astyanax mexicanus

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Using FTA® cards to store avian blood samples for genetic studies. Their application in sex determination

FTA® cards were used for long‐term storage of avian blood samples. Blood DNA was extracted by a simple method and used in PCR for sex identification of adult and nestling Great Grey Shrikes Lanius excubitor.     

Genetic Control of Spermatogenesis and Sex Determination in Mammals

The material was analyzed on the main problems of genetics of mammalian spermatogenesis, sex determination, its reversion and other defects from the standpoint of current cytological and molecular-genetic concepts of functional activity of the parental genomes after fertilization and behavior of their chromosomes at the early embryonic stages. On the basis of this analysis, a hypothesis has been proposed, which explains a high percentage (50% or more) of early embryonic mortality in placental mammals under the conditions of natural and extracorporeal fertilization, as well as regular appearance of defects in the course of natural sex determination, including the appearance of representatives of both sex minorities. We do not make pretense to comprehensive and deep analysis of male gametogenesis and sex determination in mammals.     

Relationship of lower limb height to sitting height in black populations of Africa and the United States.

This article examines a recently reported generalization. Materials from more than a score of invetigations are drawn upon. These materials show there is not a substantial research base for the claim that interbreeding in the United States between black people of African ancestry and white people of European ancestry has resulted in increased lower limb height relative to sitting height.     

Ladies last: diel rhythmicity of adult emergence in a parasitoid with complementary sex determination

Protandry, the earlier adult emergence of males, is explained as either an adaptive strategy maximizing male mating opportunities at the same time as minimizing female pre‐reproductive mortality, or as an incidental by‐product of sexual dimorphism fuelled by selection for other life‐history traits. Adult emergence sequences are monitored of broods of the gregarious larval endoparasitoid Cotesia glomerata L. (Hymenoptera: Braconidae) undergoing pupal development under different temperature regimes. As a haplodiploid species with single‐locus complementary sex determination, gender in C. glomerata is determined by the genotype at one sex locus. Haploids are always male, whereas diploids are female when heterozygous but male when homozygous at the sex locus. Sibling mating promotes homozygosity and thus the production of diploid males. Diploid males are produced at the expense of females, and impose a genetic burden on individuals and populations, despite their exceptional fertility in C. glomerata. Emergence of broods is typically completed within 2 days. Irrespective of temperature, males emerge earlier and within a shorter time interval than females, and a majority of the males in a cluster emerge before the first female. The implications of an incomplete temporal segregation of the sexes on the incidence of inbreeding in C. glomerata are discussed in the light of its sex determination mechanism and its patterns of mating, host exploitation and natal dispersal.     

Absence of repetitive DNA sequences associated with sex chromosomes in natural populations of the Trinidad guppy (Poecilia reticulata)

The genus Poecilia has been widely studied as a model for the evolution of sex chromosomes. In the course of molecular studies on population genetic structure and sexual selection in the Trinidad guppy, we examined our preparations for male-linked, repetitive DNA polymorphisms. We have not obtained any evidence of male-specific polymorphisms, in contrast to an earlier study. Our results have significant implications for theories on the evolution of sex chromosomes.Correspondence to: F. Breden     

Studies on the structure of yeast phosphofructokinase

In this paper, we describe an efficient procedure for the purification of yeast phosphofructokinase. This procedure eliminates any time delay and enables to obtain an enzyme with minimum proteolytic alterations. The molecular weights of the oligomeric enzyme and of its constitutive subunits were both evaluated by means of several independent methods. However, the accuracy of each measurement was not sufficient to discriminate between an hexameric and an octameric structure of the enzyme oligomer. On the other hand, crosslinking experiments demonstrated the octameric structure of yeast phosphofructokinase. Obviously, some methods of molecular weight determination have led to erroneous results. In particular, our experiments show that the reliability of molecular weight determinations performed by gel filtration of native proteins must be considered with caution.