Cytogenetical relationships between Rumex tuberosus,R. thyrsiflorus and R. acetosa and occurrence of polyploidy among their hybrids

Summary Reciprocal crosses were performed between Rumex tuberosus and two other taxa belonging to the Acetosa group: R. acetosa and R. thyrsiflorus. All three taxa are dioecious with the same chromosome numbers, XX + 12A, XYY+12A, but they differ from one another in the morphology of some autosomes. R. tuberosus and R. thyrsiflorus are similar in external morphology, while R. acetosa differs greatly from the other two taxa in external morphology as well as ecological characteristics.The F ₁ and F ₂ hybrids were fully vigorous and viable but their fertility was greatly reduced. Meiotic irregularities were observed in hybrids derived from all crosses. The most remarkable meiotic irregularity was diad formation after first meiotic division. The unreduced gametes derived from diads were responsible for the high frequency of polyploidy observed among the F ₂ hybrids. In the cross R. tuberosus × R. acetosa the whole F ₂ generation was tetraploid.It is concluded from the analysis performed that R. tuberosus, R. acetosa and R. thyrsiflorus are separate species, closely related to one another but already isolated by genetic and ecological barriers.     

Sixteen newH-2 haplotypes derived from wild mice

Wild mice captured in Texas, Scotland, Federal Republic of Germany, Denmark, Spain, Greece, Israel, Egypt, and Chile were mated to inbred strains and through successive backcross matings and H-2 typing lines homozygous for wild-derived H-2, haplotypes were established. The lines, which are neither congenic nor inbred, were then typed with antibodies defining known H-2 alleles at class I and class II loci. In addition, antisera were produced by the immunization of inbred strains with tissues of the new lines. Sixteen of the lines were characterized in this manner. The characterization resulted in the identification of 16 new H-2 haplotypes, 11 new K alleles, 10 new D alleles, and 21 new class I antigenic determinants, most of them of the private type. Most of the haplotypes represent natural recombinants sharing segments of the H-2 complex with previously identified haplotypes. A number of haplotypes are recombinants between the K and the A loci, which in genetic studies have proved difficult to separate. The lines, however, also provide evidence for preservation of blocks of genes in the H-2 complex, particularly in the class II region. Some of class I alleles previously found in wild mice from Michigan have now been found again in these mice. Several class II alleles of these lines appear to be the same as those found in inbred strains. Identical or nearly identical class I and class II alleles thus commonly occur in different populations. These findings strengthen the argument that in populations, H-2 alleles are relatively stable.     

The influence of negative ionization of the air on motor activity in Syrian hamsters (Masocricetus auratus Waterhouse) in light conditions

The motor activity of Syrian hamsters (Mesocricetus auratus Waterhouse) under the influence of negative ionization of the atmosphere applied for 10, 20 or 30 min per day was investigated. An ionizer with output of 14000 light negative ions per 1 cm³ of air was used. Studies carried out in the light phase of a 1212 h light/dark regime revealed a relation between the reaction of the animal and the time of day at which ionization was applied. Ionization for 20 or 30 min in the light phase decreased motor activity, while 10 min of ionization increased it compared to control animals. Ionization in the dark phase gave a more distinct rise in activity than that applied in the light phase for all three durations of ionization.This work was supported by RP-II-12 (A₁)-Investigations concerning regulation mechanisms of biorhythms by animals and humans in the basic conditions and under stress     

Urbanization reduces genetic connectivity in bobcats (Lynx rufus) at both intra– and interpopulation spatial scales

Urbanization is a major factor driving habitat fragmentation and connectivity loss in wildlife. However, the impacts of urbanization on connectivity can vary among species and even populations due to differences in local landscape characteristics, and our ability to detect these relationships may depend on the spatial scale at which they are measured. Bobcats (Lynx rufus) are relatively sensitive to urbanization and the status of bobcat populations is an important indicator of connectivity in urban coastal southern California. We genotyped 271 bobcats at 13,520 SNP loci to conduct a replicated landscape resistance analysis in five genetically distinct populations. We tested urban and natural factors potentially influencing individual connectivity in each population separately, as well as study–wide. Overall, landscape genomic effects were most frequently detected at the study–wide spatial scale, with urban land cover (measured as impervious surface) having negative effects and topographic roughness having positive effects on gene flow. The negative effect of urban land cover on connectivity was also evident when populations were analyzed separately despite varying substantially in spatial area and the proportion of urban development, confirming a pervasive impact of urbanization largely independent of spatial scale. The effect of urban development was strongest in one population where stream habitat had been lost to development, suggesting that riparian corridors may help mitigate reduced connectivity in urbanizing areas. Our results demonstrate the importance of replicating landscape genetic analyses across populations and considering how landscape genetic effects may vary with spatial scale and local landscape structure.     

Vertical migrations in two hygrophilous species of micro‐snails in relation to time of the year and habitat type

The aim of this study was to investigate vertical migration behaviors in two species of hygrophilous micro‐snails, Vertigo moulinsiana and Vertigo angustior, in relation to the time of the year (spring and summer) at two sites that differ in ground water level (periodically inundated site and non‐inundated site). The study shows different patterns of vertical migrations in the studied species. Vertigo angustior demonstrated a strong affinity to the litter layer (a weak tendency for vertical movements), independent of the time of year and site studied. By contrast, V. moulinsiana showed a clear tendency for vertical migrations, which differed depending on the time of year and site. These differences may be related to the spatial segregation of microhabitats used by these two species at the sites studied and to differences in the ability to resist inundation. Vertigo angustior is associated with microhabitats which are not subjected to prolonged inundation and tolerates a brief submersion. The periodic character of vertical migrations may suggest the effect of endogenous factors related to reproduction in V. moulinsiana. Some plasticity of this behavior in relation to habitat conditions demonstrated by this species may be an adaptation to live in unpredictably flooded environments.     

NPY and stress 30 years later: the peripheral view

Almost 30 years ago, neuropeptide Y (NPY) was discovered as a sympathetic co-transmitter and one of the most evolutionarily conserved peptides abundantly present all over the body. Soon afterward, NPY's multiple receptors were characterized and cloned, and the peptide's role in stress was first documented. NPY has proven to be pivotal for maintaining many stress responses. Most notably, NPY is known for activating long-lasting vasoconstriction in many vascular beds, including coronary arteries. More recently, NPY was found to play a role in stress-induced accretion of adipose tissue which many times can lead to detrimental metabolic changes. It is however due to its prominent actions in the brain, one of which is its powerful ability to stimulate appetite as well as its anxiolytic activities that NPY became a peptide of importance in neuroscience. In contrast, its actions in the rest of the body, including its role as a stress mediator, remained, surprisingly underappreciated and not well understood. Our research has focused on that other, "peripheral" side of NPY. In this review, we will discuss those actions of NPY on the cardiovascular system and metabolism, as they relate to adaptation to stress, and attempt to both distinguish NPY's effects from and integrate them with the effects of the classical stress mediators, glucocorticoids, and catecholamines. To limit the bias of someone (ZZ) who has viewed the world of stress through the eyes of NPY for over 20 years, fresh insight (DH) has been solicited to more objectively assess NPY's contributions to stress-related diseases and the body's ability to adapt to stress.     

Production of transmitochondrial cybrids containing naturally occurring pathogenic mtDNA variants

The human mitochondrial genome (mtDNA) encodes polypeptides that are critical for coupling oxidative phosphorylation. Our detailed understanding of the molecular processes that mediate mitochondrial gene expression and the structure–function relationships of the OXPHOS components could be greatly improved if we were able to transfect mitochondria and manipulate mtDNA in vivo. Increasing our knowledge of this process is not merely of fundamental importance, as mutations of the mitochondrial genome are known to cause a spectrum of clinical disorders and have been implicated in more common neurodegenerative disease and the ageing process. In organellar or in vitro reconstitution studies have identified many factors central to the mechanisms of mitochondrial gene expression, but being able to investigate the molecular aetiology of a limited number of cell lines from patients harbouring mutated mtDNA has been enormously beneficial. In the absence of a mechanism for manipulating mtDNA, a much larger pool of pathogenic mtDNA mutations would increase our knowledge of mitochondrial gene expression. Colonic crypts from ageing individuals harbour mutated mtDNA. Here we show that by generating cytoplasts from colonocytes, standard fusion techniques can be used to transfer mtDNA into rapidly dividing immortalized cells and, thereby, respiratory-deficient transmitochondrial cybrids can be isolated. A simple screen identified clones that carried putative pathogenic mutations in MTRNR1, MTRNR2, MTCOI and MTND2, MTND4 and MTND6. This method can therefore be exploited to produce a library of cell lines carrying pathogenic human mtDNA for further study.