Effect of cyclic AMP on retrogression of the Mullerian ducts in chick embryos]

Theophyllin and puromycine, inhibitors of the enzyme phosphodiesterase and AMPc are all able to inhibit the retrogression of mullerian ducts in the female chick embryo, grafted with an embryonic testis. We can think that these results are explained by an inhibitory action of AMPc on the mechanisms responsible for the mullerian retrogression. So the chick embryo reacts similarly as do the mammalian embryo.     

The effect of the testicular mullerian-inhibiting hormone on ovarian development in the chick embryo]

In female chick embryos grafted with embryonic testis, it is a correlation between the effects of the graft on the mullerian ducts and on the ovary. Indeed, when the graft causes retrogression of the ducts, it induces an ovarian atrophy also. These facts lead to think that these two activities are due to the same substance, the mullerian inhibiting hormone of the testis.     

Inhibiting effect of the testis on the ovary of the chick embryo]

The testicular hormone responsible for the retrogression of the mullerian ducts in the female chick embryo submitted to an embryonic testicular graft, causes an atrophy of the two, cortical and medullary, parts of this gonad, which is more marked at the level of the cortex.     

Influence of puromycin on the regression of Mullerian ducts in chick embryos submitted to a testicular graft]

Puromycin, an inhibitor of protein synthesis, strongly reduces the incidence of retrogression of the mullerian ducts provoked by testicular graft in the female chick embryo.     

Action of the testosterone treated chicken testis on the regression of the Müllerian duct]

After administration of testosterone propionate to male chick embryos and chickens, their testis have an activity, on the retrogression of mullerian ducts, much more important than that observed in testis of normal subjects of the same age, activity measured by grafting testis fragments in undifferentiated female chick embryos. The results suggest that testosterone gives such an effect by inhibiting pituitary gonadotropins, peculiarly FSH.     

Anatomical basis for vascular-pedicle transplantation of the hypothalamo-hypophyseal complex

In 240 corpses of mature persons by means of complex morphological methods extraorganic arteries of the hypophysis, anterior hypothalamus have been investigated, as well as topography of the arterial peduncle of the hypothalamo-hypophyseal complex. Blood supply of the hypophysis and of the anterior hypothalamic part is performed from one common vascular pool--the arterial ring of the brain via multiple arterial branches, their amount and diameter varying considerably. Taking into account an important role of anastomotic vessels and numerous arterial plexuses, when the hypothalamo-hypophyseal complex is extirpated for investigation, it is necessary to include into its composition, besides the major arterial peduncle, the optic chiasm, the grey tuber and the system of cavernous sinuses. Owing to this, there is no need to separate the arterial peduncle of the transplant at the moment of obtaining the hypothalamo-hypophyseal complex. The topographic anatomical investigations performed make prerequisites for transplantation of the hypothalamo-hypophyseal complex on the vascular peduncle in clinic.     

Brain – Hatschek's pit relationships in amphioxus species

The vertebrate hypothalamo-hypophyseal neurosecretory system is a complex anatomical device for central nervous control over secretion of pituitary hormones. Since it is present in the most primitive vertebrates, the cyclostomes, it is of interest to look for a possible invertebrate anatomical equivalent, or precursor, for clues as to its evolution. We have found in six species of amphioxus, members of an invertebrate group (cephalochordates), considered to be closest to the vertebrates, that there is a morphologically equivalent neuro-epithelial complex, that in many ways resembles the hypothalamo-hypophyseal system of vertebrates. In the six amphioxus species described here the nervous element is a ventral lobe of the brain, the infundibulum, that extends downward along the right side of the notochord, and ends near the dorsal surface of a Rathke's pouch-like structure known as Hatschek's pit. This part of Hatschek's pit has been found earlier to contain a vertebrate LH-like gonadotropin. Therefore, the infundibulum-Hatschek's pit system of amphioxus may be involved in regulating the seasonal reproductive cycle, and it appears to be a direct homologue of the vertebrate hypothalamo-hypophyseal neurosecretory system functionally as well as morphologically.     

Current findings on the asymmetric growth of the mullerian tract in female chick embryos]

Shape and orientation of the mesothelial cells were examined in the mullerian ducts of 8, 13 and 15 day female chick embryos with the scanning electron microscope. The observed evolution in the pattern of these cells likely reflects the mechanical conditions to which these organs are subjected during embryonic development: stretching for the left duct, slackening for the right duct. These observations, together with data concerning growth of these organs, suggest that topographical relationships between cells, which in this system result from mechanical factors, play an important role in controlling cell proliferation.     

Mechanism of the regulation of microvascular vasoconstriction and vasodilation

Basing on double reciprocal innervation and regulation with its cholinergic (parasympathetic part) and adrenergic components, mechanisms of vasoconstriction and vasodilation of microvessels are considered. The latter are presented as a multicontour system, including the central adrenergic contour, two terminal contours, in the form of terminal arcs of cholinergic and adrenergic type, two neurohormonal contours also of cholinergic and adrenergic type, passing through the hypothalamo-hypophyseal complex.     

Synergistic cooperation between the beta-catenin signaling pathway and steroidogenic factor 1 in the activation of the Mullerian inhibiting substance type II receptor

Mullerian inhibiting substance type II receptor (MISRII) is a member of the transforming growth factor-beta superfamily. Mutations in mullerian inhibiting substance (MIS) or MISRII cause male sexual abnormalities, persistent mullerian duct syndrome, and pseudohermaphroditism. The spatial and temporal regulation of MIS and MISRII is important for its biological action. Male Wnt7a mutant mice do not undergo regression of mullerian ducts. Here we showed that the canonical Wnt signaling pathway regulated MISRII. The promoter MISRII was activated by beta-catenin expression, and this activation was dependent on TCF4-binding sites. The nuclear receptor superfamily member steroidogenic factor 1 (SF1) synergistically activated the MISRII promoter with beta-catenin. APC, a negative regulator of Wnt signaling, decreased SF1-mediated activation of the MISRII promoter in the colon carcinoma cell line SW480. We also showed a direct physical interaction between beta-catenin and SF1 by co-immunoprecipitation. Thus, our findings suggest that MISRII is a developmental target of Wnt7a signaling for mullerian duct regression during sexual differentiation.     

Effect of pharmacological block of individual sections of the hypothalamo-hypophyseal-adrenal system on its function in acute hemic hypoxia]

Experiments on 228 male albino rats revealed an increase in the functional activity of all the sections of the hypothalamo-hypophyseal adrenal neurosecretory system. A degree of a functional activity of this system was of great significance in the development of the organism's resistance to hypoxia. The leading section of the activation of this system was secretion of the corticotropine-releasing factor of the hypothalamus.     

睫状神经营养因子对体外培养骨骼肌细胞的促增殖效应

目的 :探讨睫状神经营养因子 (CNTF)对骨骼肌细胞的直接营养作用 ,从而为神经肌肉系统损伤和退行性病变的治疗提供新的思路。结果 :CNTF可以促进体外培养的L6 TG肌母细胞和新生SD大鼠原代骨骼肌细胞增殖。结论 :CNTF对体外骨骼肌细胞具有营养作用。CNTF的神经和肌肉双重营养性能使其可能在神经肌肉损伤和退行性病变的治疗上发挥重要作用。     

厦门木麻黄种群交配系统及近交衰退

木麻黄耐沙生,盐碱,是沿海优良的防护林树种,从20世纪80年代开始,木麻黄林呈现出衰退现象。采用等位酶分析技术研究木麻黄种群的交配系统及近交衰退,木麻黄种群异交率为0．622,表明为混合酱类型,与其亲缘种比较来看,引种降低了木麻黄异交率,增加了近交,采用电是接估算的近交衰退程度很高。结果表明,引种过程中的建立者效应引起的近交及其后的近交衰退确定在木麻黄林衰退中起了重要作用,根据基因型有选择地引起木麻黄以减轻衰退。     

Hypothalamo-hypophyseal system and thyroid gland of Acipenser güldenst?dti sturgeon fry during temperature changes

In the parr of the sturgeon (body length varies from 6.1 to 14.0 cm) histometric studies have been made on the elements of hypothalamo-hypophyseal neurosecretory system, tireotropic cells (TC) of the hypophysis and the thyroid gland (TG) during the decrease of water temperature from 24--27 degrees to 10--14 degrees. It was shown that in all size groups of the fish an increase in the number, growth and differentiation of neurosecretory cells in the dorsal part of the preoptic nucleus are taking place. Correlation was found between the activity of neurosecretory cells of the dorsal part of the preoptic nucleus and hypophyseal TC. The response to the decrease in water temperature follows the pattern of stress reaction, being expressed to different extent in various size groups of the parr depending on the initial condition of the functional complex investigated.     

Lichen Specific Thallus Mass and Secondary Compounds Change across a Retrogressive Fire-Driven Chronosequence

In the long-term absence of major disturbances ecosystems enter a state of retrogression, which involves declining soil fertility and consequently a reduction in decomposition rates. Recent studies have looked at how plant traits such as specific leaf mass and amounts of secondary compounds respond to declining soil fertility during retrogression, but there are no comparable studies for lichen traits despite increasing recognition of the role that lichens can play in ecosystem processes. We studied a group of 30 forested islands in northern Sweden differing greatly in fire history, and collectively representing a retrogressive chronosequence, spanning 5000 years. We used this system to explore how specific thallus mass (STM) and carbon based secondary compounds (CBSCs) change in three common epiphytic lichen species (Hypogymnia phsyodes, Melanohalea olivacea and Parmelia sulcata) as soil fertility declines during this retrogression. We found that STMs of lichens increased sharply during retrogression, and for all species soil N to P ratio (which increased during retrogression) was a strong predictor of STM. When expressed per unit area, medullary CBSCs in all species and cortical CBSCs in P. sulcata increased during retrogression. Meanwhile, when expressed per unit mass, only cortical CBSCs in H. physodes responded to retrogression, and in the opposite direction. Given that lichen functional traits are likely to be important in driving ecological processes that drive nutrient and carbon cycling in the way that plant functional traits are, the changes that they undergo during retrogression could potentially be significant for the functioning of the ecosystem.     

Decoupled responses of tree and shrub leaf and litter trait values to ecosystem retrogression across an island area gradient

Aims

In the long term absence of catastrophic disturbance ecosystem retrogression occurs, and this is characterized by reduced soil fertility, and impairment of plant biomass and productivity. The response of plant traits to retrogression remains little explored. We investigated how changes plant traits and litter decomposability shift during retrogression for dominant trees and understory shrubs.

Methods

We characterized changes in intraspecific, interspecific and community-averaged values of plant traits and litter decomposability, for six abundant species across thirty lake islands in boreal forest that undergo retrogression with increasing time since fire.

Results

For understory shrubs, trait values and litter decomposability often changed as soil fertility declined in a manner reflective of greater conservation (versus acquisition) of nutrients, particularly at the interspecific and whole community levels. Such responses were seldom observed for trees, meaning that trees and shrubs show a decoupled response to declining soil fertility during retrogression.

Conclusions

Our results only partially agree with previous studies on temperate and subtropical retrogressive chronosequences. Because traits of only shrubs were responsive, they also highlight that impairment of belowground ecosystem processes during retrogression is primarily driven by changes in the trait spectra of understory vegetation rather than that of the trees.     

The influence of the antimitotic drug CCNU on the neurosecretion of rat hypothalamo-hypophyseal system

The purpose of this investigation was to evaluate the influence of the antimitotic drug CCNU on the morphology of the hypothalamo-hypophyseal neurosecretory system of rat. Adult Wistar rats were treated intragastrically with 2.5 mg CCNU once a week during 3 consecutive weeks and 5 mg at the end of the 4th week. The brains and hypophyses were fixed in Zenker-formol solution. Paraffin slices were stained with chromhematoxylin to demonstrate neurosecretory material and with cresyl violet. PAS reaction was also performed. The experiment resulted in disturbances of the neurosecretory function of the hypothalamo-hypophyseal system in form of alteration in the content of neurosecretion in the neuronal cytoplasm and processes within supraoptic and paraventricular nuclei as well as in the neurohypophysis. The morphometric measurements showed enlargement of the cell nuclei and cytoplasm volumes in the nucleus supraopticus of hypothalamus.     

Role of Wilms tumor 1 (WT1) in the transcriptional regulation of the Mullerian-inhibiting substance promoter

The Wilms tumor 1 (WT1) gene product may regulate the mullerian-inhibiting substance (MIS) gene, because mutations in WT1 can cause persistence of the mullerian duct in men. In the present study, we show by gel shift and chromatin immunoprecipitation assays that WT1 bound to a GC-rich sequence in the murine Mis promoter. Mutation in this site abolished WT1-mediated activation of the Mis promoter. The WT1, SRY box protein 9, and steroidogenic factor 1 could synergistically activate the Mis promoter, and at least two factors were necessary for minimal activation. The WT1 is an essential factor for activation of the Mis promoter; therefore, the persistence of the mullerian duct in patients with Denys-Drash syndrome may result from deregulation of the MIS gene.     

Radioimmunocytochemical localization of corticotropin-releasing factor and adrenocorticotropin in the hypothalamo-hypophyseal system of the rat: effects of adrenalectomy.

Various radioimmunocytochemical approaches have been utilized to localize primary antibody-antigen complexes. Here we examined the binding properties of three different radioiodinated compounds for their ability to label the antibody-antigen complex, including: donkey anti-rabbit immunoglobulin, donkey anti-rabbit F(ab')2-IgG, and a biotinylated goat anti-rabbit secondary antibody followed by [125I]-avidin. These probes were used to localize rabbit primary antisera against corticotropin-releasing factor (CRF) and adrenocorticotropin-releasing hormone (ACTH) in the hypothalamo-hypophyseal system of the rat. The pattern of labeling with each radiolabeled probe was consistent with the light microscopic immunocytochemical staining for CRF and ACTH. The utility of the radioimmunocytochemical method for quantitative analyses was further tested by studying the effects of adrenalectomy (ADX) on the levels of immunoreactive CRF and ACTH in the hypothalamo-hypophyseal system. Computer-assisted microdensitometric analysis of immunoreactive CRF levels in the median eminence indicated that there was a 33% decrease 24 h after ADX. Immunoreactive ACTH levels in the anterior pituitary were significantly decreased from 1 day (38%) to 1 week (36%) after ADX and were increased at 2 weeks (89%). The changes in CRF and ACTH levels, as measured radioimmunocytochemically after ADX, were consistent with previous biochemical studies. These results indicate that computer-assisted radioimmunocytochemical analysis can be used quantitatively to measure immunoreactivity in tissue sections. The high resolution and high sensitivity provided by this method should make it widely applicable.