New evidences for participation of biogenic monoamines in androgen-dependent sexual differentiation of hypothalamic control of gonadotropin secretion in rats.

Corpora lutea have been found in the ovarian tissue transplanted into the anterior ocular chamber of castrated two-month-old male rats receiving on 3rd through 7th post-natal days alpha-methyl-p-tyrosine or p-chlorophenylalanine. Administration of these agents in combination with testosterone propionate to newborn female rats prevented essentially development of the anovulatory syndrome and maintained a normal picture of vaginal smears, ovarian and uterine structure as well as cyclic changes of adenohypophyseal and blood plasma lutropin contents and normal levels of estradiol and progesterone in the blood plasma except of progesterone level in animals receiving alpha-methyl-p-tyrosine. The preventive effect of the adrenoblocking agents droperidol and propranolol was weak and inconstant. Results suggest participation of catecholamines and serotonin in the androgen-dependent sexual differentiation of the brain in rats.     

Proinflammatory Cytokines and Skin Wound Healing in Mice

Molecular Biology - Skin wound healing is subject to an intricate regulation, involves many cell populations and molecular mediators, and is one of the key mechanisms that ensures the barrier...     

PULSED‐FIELD GEL ELECTROPHORESIS ANALYSIS OF GENOME SIZE AND STRUCTURE IN PAVLOVA GYRANS AND DIACRONEMA SP. (HAPTOPHYTA)1

Information regarding genome size and structure is a prerequisite for selecting model organisms and for facilitating the most efficient study of their chromosomal DNA. The goal of this study was to identify future candidates for complete‐genome‐sequencing projects among economically or evolutionarily important species of haptophyte algae. Using pulsed‐field gel electrophoresis (PFGE), we identified relatively small genomes and chromosome sizes in two haptophyte species from the class Pavlovophyceae, Pavlova gyrans Butcher and Diacronema sp. The basal position of Pavlovophyceae in the Haptophyta; the key position of this group in the chromalveolates; and their economic and potential biomedical importance, ease of culturing, and small genome size make these taxa ideal models for complete‐genome sequencing.     

Provision of nestboxes raises the breeding density of Great Tits Parus major equally in coniferous and deciduous woodland

Nestbox provision is a technique used to increase nest-site availability for secondary cavity-nesting birds. However, little is known about the demographic consequences of nestbox provision in different habitat types. To assess how nestbox provision affects the density of hole-nesting birds simultaneously in two contrasting habitats, we compared the breeding density of Great Tits along transects without nestboxes with that in transects where nestboxes were provided. Although the initial density of breeders was considerably higher in the deciduous habitat than in the coniferous habitat, provision of nestboxes increased density by a similar number of additional pairs in each habitat type. Thus, the provision of nestboxes in managed coniferous forests may be as effective in increasing the breeding opportunities of cavity nesters as in deciduous stands. Moreover, previous research showed that pairs in deciduous habitat with nestboxes have consistently lower breeding success than those in coniferous habitat with nestboxes. It is possible that the addition of nestboxes in the preferred habitat increased density to such an extent that density-dependent effects became apparent.     

Catecholamines in steroid-dependent brain development

Sex-specific peculiarities of catecholamine (CA) content and turnover in neuroendocrine brain areas and their modification with neonatal steroids or prenatal stress (PS) in Wistar rats were studied. No changes in noradrenaline (NA) content and turnover rate were found in the preoptic area (POA), meanwhile dopamine (DA) turnover rates in the POA and mediobasal hypothalamus (MBH) were increased in neonatally androgenized 10-day-old females. Treatment of female neonates with various catecholestrogens increased hypothalamic NA content by 30–95% but only 4-hydroxyestradiol-17β induced anovulation. 6-Hydroxydopamine had no significant impact on hypothalamic CA content in neonates and did not prevent testosterone-induced persistent estrous. Maternal stress (restriction for 1 h a day, 15–21st days of pregnancy) resulted in a decrease of hypothalamic NA and blood plasma corticosterone response to acute stress in adult male offspring. Sex differences in CA content in the POA and MBH disappeared in 10-day-old prenatally stressed rats. Conclusions: (1) sexual brain differentiation needs co-operative actions of sex steroids and CA to be completed; and (2) early changes in CA content and turnover induced by PS or neonatal steroid exposure predetermine long-term alterations of the stress responsiveness, reproductive behaviour and neuroendocrine control of ovulation.