Evidence of inhibin/activin subunit betaC and betaE synthesis in normal human endometrial tissue

Background  

Inhibins are important regulators of the female reproductive system. Recently, two new inhibin subunits betaC and betaE have been described, although it is unclear if they are synthesized in normal human endometrium.     

Inhibin/activin subunits alpha, beta-A and beta-B are differentially expressed in normal human endometrium throughout the menstrual cycle

Inhibins are dimeric glycoproteins composed of an alpha (alpha) subunit and one of two possible beta (beta-) subunits (betaA or betaB). The aims of this study were to assess the frequency and tissue distribution patterns of the inhibin subunits in normal human endometrium. Samples from human endometrium from proliferative phase (PP; n=32), early secretory phase (ES; n=10) and late secretory phase (LS; n=12) were obtained. Immunohistochemistry, immunofluorescence and a statistical analysis were performed. All three inhibin subunits were expressed by normal endometrium by immunohistochemistry and immunofluorescence. Inhibin-alpha was primarily detected in glandular epithelial cells, while inhibin-beta subunits were additionally localised in stromal tissue. Inhibin-alpha staining reaction increased significantly between PP and ES (P<0.05), PP and LS (P<0.01), and ES and LS (P<0.02). Inhibin-betaA and -betaB were significant higher in LS than PP (P<0.05) and LS than ES (P<0.05). All three inhibin subunits were expressed by human endometrium varying across the menstrual cycle. This suggests substantial functions in human implantation of inhibin-alpha subunit, while stromal expression of the beta subunits could be important in the paracrine signalling for adequate endometrial maturation. The distinct expression in human endometrial tissue suggests a synthesis of inhibins into the lumen and a predominant secretion of activins into the stroma.     

Immunohistochemical analysis of steroid receptors and glycodelin A (PP14) in isolated glandular epithelial cells of normal human endometrium

Highly purified fractions of isolated endometrial cells can be useful for investigating endometrial function. After a first collagenase digestion, normal human endometrial stromal and epithelial cells were separated by filtration. Glands were purified further by two collagenase digestion steps, filtration, differential sedimentations, and Ficoll gradient centrifugation. Epithelial cells were polyhedral and grew as islands in a whorl-like wavy pattern around glandular fragments. High cell culture purity was confirmed with the positive immunohistochemical reaction against cytokeratin 7,8,18,19. Isolated human glands had a similar distribution pattern of estrogen receptor (ER) and progesterone receptor (PR) as observed in vivo, suggesting that glands have a functional hormone receptor system at the time of plating. Using a specific monoclonal antibody against glycodelin A (GdA), a characteristic cyclical expression was demonstrated during the menstrual cycle. The GdA reaction was weak in the proliferative phase, increasing significantly till the late secretory phase, suggesting a similar GdA concentration in vitro as observed in vivo glands. In conclusion, this method could be a model for studying endometrial glandular cells from different menstrual phases, endometrial cell interactions, implantation mechanisms, GdA regulation mechanisms, and pharmacological or other influences on ER and PR alteration.     

Coordination properties of Cu(II) and Ni(II) ions towards the C-terminal peptide fragment -ELAKHA- of histone H2B

The coordination properties of the peptide Ac-GluLeuAlaLysHisAla-amide, the C-terminal 102-107 fragment of histone H2B towards Cu(II) and Ni(II) ions were studied by means of potentiometry and spectroscopic techniques (UV/Vis, CD, EPR and NMR). It was found that the peptide has a unique ability to bind Cu(II) ions at physiological pH values at a Cu(II): peptide molar ratio 1:2, which is really surprising for blocked hexapeptides containing one His residue above position 3. At physiological pH values the studied hexapeptide forms a CuL(2) complex {N(Im),2N(-)}, while in acidic and basic pH values the equimolar mode is preferred. In basic solutions Ac-GluLeuAlaLysHisAla-amide may bound through a {4N(-)} mode forming a square-planar complex, in which the imidazole ring is not any more coordinated or it has been removed in an axial position. On the contrary, Ni(II) ions form only equimolar complexes, starting from a distorted octahedral complex at about neutral pH values to a planar complex, where hexapeptide is bound through a {N(Im),3N(-)} mode in equatorial plane. The results may be of importance in order to reveal more information about the toxicity caused by metals and furthermore their influence to the physiologic metabolism of the cell.     

Phylogenetic relationships and evolutionary history of snake-eyed skink Ablepharus kitaibelii (Sauria: Scincidae)

Sequence data derived from two mitochondrial markers, 16S rRNA and cytochrome b genes, were used to infer the phylogenetic relationships of 38 populations of the snake-eyed skinks of the genus Ablepharus with emphasis on A. kitaibelii from Greece and Turkey. The partition-homogeneity tests indicated that the combined data set was homogeneous, and maximum-parsimony, maximum-likelihood, and Bayesian analyses produced topologically identical trees that revealed a well-resolved phylogeny. All species except A. kitaibelii form monophyletic units. The latter species appears paraphyletic with respect to A. budaki and A. chernovi with populations clustering into two distinct clades. A. chernovi and A. budaki, which have recently been raised to species status, were confirmed as genetically distinct forms. We used sequence divergence and paleogeographic history of the Aegean region to reconstruct a biogeographic evolutionary scenario for A. kitaibelii.     

The phylogeography of the gecko Cyrtopodion kotschyi (Reptilia: Gekkonidae) in the Aegean archipelago

Cyrtopodion kotschyi is a small gecko, widely distributed on the islands of the Aegean archipelago and the adjacent mainland. We unveiled the phylogeography of the species by using a portion of the cytochrome oxidase I mitochondrial DNA gene from 35 insular and mainland populations. The distinct geographic distribution of the major clades of the phylogenetic tree and its topology suggest a spatial and temporal sequence of phylogenetic separations that coincide with some major paleogeographical separations during the geological history of the Aegean and support a mainly vicariant pattern of differentiation. The separation times and 95% confidence limits among the different clades were estimated according to two different paleogeographical scenarios. The very high interpopulation genetic divergence (up to 20% uncorrected pairwise distances) and the better concordance between paleogeographical and phylogenetic separations for one of the scenarios suggest that species differentiation started during Miocene (about 10 Mya) due to the fragmentation of the united landmass of "Agais" that was Aegean at that time.     

Use of GnRHa-delivery systems for the control of reproduction in fish

The most commonly observed reproductivedysfunctions in cultured fish are theunpredictability of final oocyte maturation(FOM) in females, and the diminished volume andquality of sperm in males. Gonadotropin-releasing hormone agonists (GnRHa)have been used extensively in order tostimulate the release of pituitary luteinizinghormone (LH) required to induce FOM, ovulationand spermiation. Because multiple hormonaltreatments are often necessary for a successfulresponse, fish must be monitored and handledextensively, which is labor intensive,stressful to the fish and can often result inbroodstock mortalities. To ameliorate thisproblem, sustained-release delivery systems forGnRHa have been developed during the last twodecades and have been increasingly applied incontrolling reproduction of a variety ofcultured fish. Solid implants of cholesterolor poly[ethylene-vinyl acetate], andbiodegradable microspheres ofpoly[lactide-glycolide] or poly[fatty aciddimer-sebasic acid] release GnRHa for a periodof time (from a few days to many weeks.) GnRHa-delivery systems do not causedesensitization of the pituitary gonadotrophsin fish, and by stimulating a sustainedelevation of plasma LH they induce the naturalprogression of plasma steroid increasesassociated with FOM and spermiation. Thismethod has been used with very encouragingresults in females of more than 40 culturedspecies and has been effective in inducing FOM,ovulation or spawning in fish with synchronous,group-synchronous and asynchronous ovariandevelopment. In males, GnRHa-delivery systemshave been tested in more than 20 species,producing significant increases in miltproduction for up to 5 weeks. Future researchshould focus on the optimization of thistechnology in terms of (a) using the mostpotent GnRHa, (b) identifying the mostappropriate GnRHa release kinetics according tothe reproductive biology of different species,and (c) determining minimum effective doses. Developments in these areas will greatlyenhance the effectiveness and efficiency ofGnRHa-delivery systems, while at the same timereducing their cost thus making them moreaffordable to the aquaculture industry.     

A review of phylogeographic analyses of animal taxa from the Aegean and surrounding regions

We provide a review and synthesis of key findings in phylogeographic research on terrestrial animals in the Aegean archipelago (Greece) and surrounding regions (Greek mainland, southern Balkans and Asia Minor). A critical review of more than 100 phylogeographic articles on 76 animal genera (30 invertebrates and 46 vertebrates) that have been published so far for the region leads to the recognition of three types of distribution patterns: old ‘colonizers’ diversified in the Aegean before the formation of the mid‐Aegean Trench (MAT – i.e. before 9 Mya), post‐MAT colonizers that arrived to the Aegean in late Miocene and Pliocene and new colonizers that inhabited the region in the Pleistocene or even the Holocene. Several problems, mainly regarding the use of calibration points and/or molecular clock rates for clade chronology, have been identified in many analyses. Despite the large amount of phylogeographic work concerning the Aegean and surrounding regions, many groups remain unstudied (especially invertebrates, micro‐organisms, fungi and plants), and many issues still remain unresolved. The relative roles of extinction, speciation, dispersal and vicariance, as well as the effects of adaptive and non‐adaptive components of diversification, need further analyses with modern tools that can provide deeper insights. A more detailed reconstruction of the palaeogeography of the region is also of prime importance. The critical views presented herein may prove useful also for the evaluation of similar work in other regions.     

Inferring phylogenetic patterns of land snails of the genus Albinaria on the island of Dia (Crete,Greece)

Albinaria (Gastropoda, Clausiliidae) is a pulmonate genus distributed around the north-eastern coasts of the Mediterranean. It is the most 'speciose' genus within the family of Clausiliidae, exhibiting a high degree of morphological and genetic differentiation, and serving as a model for several ecological, systematics and evolutionary studies. Nevertheless, many aspects remain uncertain mainly due to the large number of taxa whose classification has not yet been evaluated with solid synapomorphic characters. Thirty-one morphological species are currently recognized on the island of Crete and its satellite islets. Four of them (A. retusa, A. torticollis, A. jaeckeli, and A. teres) are distributed on the island of Dia (north of Crete); the first three are island endemics. Here, we combined mitochondrial and nuclear DNA information and Bayesian and Maximum Likelihood approaches to evaluate the phylogenetic relationships, and assess the genetic distinctiveness and cohesiveness of all described species of Dia Island. The produced phylogeny was not congruent with the morphological species, demonstrating a more complex pattern of speciation and diversification. Although each island endemic constitutes a monophyletic lineage, the number of island endemic species could be greater than the three currently recognized species so far (A. retusa, A. torticollis, and A. jaeckeli), since a newly discovered lineage (north-western part of the island), that morphologically differs from the populations of A. torticollis in the eastern part, and genetically is more closely related to A. jaeckeli, could be elevated to the species level. Considering the fourth species found on the island of Dia, A. teres is genetically highly variable, showing low geographic structuring due to either long-distance gene flow or retained ancestral polymorphisms, or a combination of both. Further work (analysis of more specimens and DNA data) both from Dia and Crete is indispensable in order to shed light on aspects of the evolutionary history of the genus in Dia.