The ultrastructure of formed white blood elements (neutrophils) in schizophrenia.

A comparative electronmicroscopic study of neutrophils in schizophrenic patients and in healthy control subjects has revealed a certain difference in the ultrastructure of blood cell formation. This difference concerns the coarse-grained chromatin, the osmiophility of nuclear membrane, the enlargement of perinuclear halo, the enlightenment of matrix, the enlargement of glycogen granules, the swelling of mitochondria, the change in the amount of free ribosomes, an increase in the number of azurophilic granules and a decrease in the specific ones.     

The MHC: relationship between linkage and function.

It is intriguing that several genes with associated functions, including all of class I and class II genes, as well as some genes affecting antigen presentation of both class I and class II pathways, are linked in the MHC. Recent observations have led to speculation that there may be a functional explanation for keeping these related genes together.     

The use of 75selenomethionine for labelling the formed and protein elements of the blood.

In the introduction the authors describe the biological role of platelets, plasma protein, fibrinogen and erthrocytes as well as the methods of tagging, separating and measuring them. The advantage of platelet labelling with 75selenomethionine is that it allows production and life-span to be determined simultaneously, however, the in vivo measurements do not give information on the site of platelet sequestration. Protein anabolism as well as katabolism can be evaluated with it, and the simultaneous determination of platelet and fibrinogen turnover may be especially useful in pathological conditions. The determination of erythrocyte life-span with 75 selenomethionine does not give so much information as the 59Fe and 51Cr methods, but when used for the examination of cell kinetics in combination with the latter methods it may afford an insight into erythropoiesis. The biological and the effective half-life periods (Teff) of 75selenomethionine are probably shorter than indicated in the literature.     

The relationship between chromatid interference and the mapping function.

A formula for a general mapping function involving only the number of chiasmata between two points on the chromosome and the average excess of four-stranded double exchanges over two-stranded double exchanges is derived. A formula is also given for deriving the proportion of three-stranded double exchanges after any given number of chiasmata; this is related to mapping for linkage with the centromere. It is shown that this proportion tends to a limit of 2/3 after a large number of chiasmata, whether or not chromatid interference is operating.     

The dynamic relationship between polyandry and selfish genetic elements

Selfish genetic elements (SGEs) are ubiquitous in eukaryotes and bacteria, and make up a large part of the genome. They frequently target sperm to increase their transmission success, but these manipulations are often associated with reduced male fertility. Low fertility of SGE-carrying males is suggested to promote polyandry as a female strategy to bias paternity against male carriers. Support for this hypothesis is found in several taxa, where SGE-carrying males have reduced sperm competitive ability. In contrast, when SGEs give rise to reproductive incompatibilities between SGE-carrying males and females, polyandry is not necessarily favoured, irrespective of the detrimental impact on male fertility. This is due to the frequency-dependent nature of these incompatibilities, because they will decrease in the population as the frequency of SGEs increases. However, reduced fertility of SGE-carrying males can prevent the successful population invasion of SGEs. In addition, SGEs can directly influence male and female mating behaviour, mating rates and reproductive traits (e.g. female reproductive tract length and male sperm). This reveals a potent and dynamic interaction between SGEs and polyandry highlighting the potential to generate sexual selection and conflict, but also indicates that polyandry can promote harmony within the genome by undermining the spread of SGEs.