Effects of IL-18 on the proliferation and steroidogenesis of bovine theca cells: Possible roles in the pathogenesis of polycystic ovary syndrome

Interleukin 18 (IL-18) is a pleiotropic pro-inflammatory cytokine and is associated with arrested follicle development and anovulation which are the typical pathological changes of PCOS. Theca cells (TCs) have a key role in follicular growth and atresia. But whether IL-18 can directly affect ovarian TCs function is unknown. Therefore, the objective of this study was to determine the effect of IL-18 on proliferation and steroidogenesis of bovine TCs and to explore the biological effect of IL-18 on folliculogenesis. This work revealed that at 300-1000 pg/mL, IL-18 led to a time- and dose-dependently increase in cell proliferation (P < .05). IL-18 increased 17-hydroxyprogesterone (17OHP4) and androstenedione (A2) secretion with up-regulation of key steroidogenesis-related genes CYP11A1 and CYP17A1 (P < .05). Furthermore, our data demonstrated that the IL-18R protein is predominantly expressed in small-follicle (3-6 mm) TCs than large follicles (8-22 mm) by immunohistochemistry. We also found that the stimulation effects of IL-18 on TCs can be reversed with the addition of IL-18BP as early as at 4 hours of culture and reached the peak at 16 hours. We conclude that IL-18 appears to target TCs in bovine, and suggest an important role for this cytokine in ovarian function. Present findings further validate potential effects of IL-18 in the conditions associated with follicular dysplasia and excessive growth of ovarian TCs (such as PCOS). But additional research is needed to further understand the mechanism of action of IL-18 in theca cells as well as its precise role in folliculogenesis.     

Sperm head shaping in ratites: New insights,yet more questions

Head shaping in mammalian sperm is regulated by a number of factors including acrosome formation, nuclear condensation and the action of the microtubular manchette. A role has also been suggested for the attendant Sertoli cells and the perinuclear theca (PT). In comparison, relatively little information is available on this topic in birds and the presence of a PT per se has not been described in this vertebrate order. This study revealed that a similar combination of factors contributed to head shaping in the ostrich, emu and rhea, although the Sertoli cells seem to play a limited role in ratites. A fibro-granular structure analogous to the mammalian PT was identified, consisting of sub- and post-acrosomal components. The latter was characterized by stage-specific finger-like projections that appeared to emanate from the cytoplasmic face of the nuclear envelope. They were particularly obvious beneath the base of the acrosome, and closely aligned, but not connected to, the manchette microtubules. During the final stages of chromatin condensation and elongation of the sperm head the projections abruptly disappeared. They appear to play a role in stabilizing the shape of the sperm head during the caudal translocation of the spermatid cytoplasm.     

Structure and formation of the perforated theca defining the Pelagophyceae (Heterokonta), and three new genera that substantiate the diverse nature of the class

The pelagophytes, a morphologically diverse class of marine heterokont algae, have been historically united only by DNA sequences. Recently we described a novel perforated theca (PT) encasing cells from the Pelagophyceae and hypothesized it may be the first morphological feature to define the class. Here we consolidate that observation, describing a PT for the first time in an additional seven pelagophyte genera, including three genera new to science. We established clonal cultures of pelagophytes collected from intertidal pools located around Australia, and established phylogenetic trees based on nuclear 18S rDNA and plastid rbcL, psaA, psaB, psbA and psbC gene sequences that led to the discovery of three new species: Wyeophycus julieharrissiae and Chromopallida australis form a distinct lineage along with Ankylochrysis lutea within the Pelagomonadales, while Pituiglomerulus capricornicus is sister genus to Chrysocystis fragilis in the Chrysocystaceae (Sarcinochrysidales). Using fixation by high-pressure freezing for electron microscope observations, a distinctive PT was observed in the three new genera described in this paper, as well as four genera not previously investigated: Chrysoreinhardia, Sargassococcus, Sungminbooa and Andersenia. The mechanism of PT formation is novel, being fabricated from rafts in Golgi-derived vesicles before being inserted into an established PT. Extracellular wall and/or mucilage layers assemble exterior to the PT in most pelagophytes, the materials likewise secreted by Golgi-derived vesicles, though the mechanism of secretion is novel. Secretory vesicles never fuse with the plasma membrane as in classic secretion and deposition, but rather relocate extracellularly beneath the PT and disintegrate, the contents having to pass through the PT prior to wall and/or mucilage synthesis. This study substantiates the diverse nature of pelagophytes, and provides further evidence that the PT is a sound morphological feature to define the Pelagophyceae, with all 14 of the 20 known genera studied to date by TEM possessing a PT.     

The diversity of stamen structures and dehiscence patterns among Magnoliidae

ENDRESS, P. K. & HUFFORD, L. D., 1989. The diversity of stamen structures and dehiscence patterns among Magnoliidae . Structure of stamens, particularly the patterns of anther dehiscence were studied over a wide range of families of the Magnoliidae with emphasis on the Magnoliales and Laurales as the most conservative orders of the angiosperms. Valvate dehiscence by proximal and distal stomial bifurcation was found (in addition to the already known Sarcandra and Polyalthia) for the first time in Degeneriaceae, Himantandraceae, Eupomatiaceae, in some additional Annonaceae, and in Peumus of the Monimioideae sensu lata. At least proximal bifurcations of the stomia occur in some Magnoliaceae and Ranunculaceae. An endothecial-like connective hypodermis was found (in addition to the already known Chloranthaceae and Magnoliaceae) in some Annonaceae, in Pseudowintera (Winteraceae), and in Thalictrum (Ranunculaceae). In the Annonaceae an endothecial-like connective hypodermis is partly correlated with valvate dehiscence by stomial bifurcations (as in many Hamamelididae). However, in many Magnoliidae stamens with this valvate pattern the anther is massive, especially in ‘laminar’ stamens, and the counterforce to the opening valves is therefore provided on the morphological and not on the histological level. Concomitant with valvate dehiscence by circular or elliptic flaps in the Laurales is often structural and functional dissocation of the two pollen sacs of a thcca, which is expressed by: (1) independent opening of each pollen sac, (2) lack of disruption of the interlocular zone of a theca, (3) frequent occurrence of asymmetry of the two pollen sacs of the theca, (4) frequent loss of one pollen sac per theca. In Berberidaceae with similar flaps asymmetry of the two pollen sacs of a theca is also common. These finds, together with the detection by paleobotanists of valvate anthers from the Lower Cretaceous, point to the probability that valvate anthers were more common in primitive angiosperms than previously thought.     

Unique preservation of siliceous dinoflagellate motile cells from the Oligocene fossil Lagerstätte of Sieblos,Germany

The Triassic to Recent fossil record of the dinoflagellates is represented overwhelmingly by geologically resistant, organic-walled, non-motile resting cysts; such cysts are formed following the sexual phase in the life cycle. Very few confirmed records exist of the motile stage being preserved in the fossil record. This paper reports the occurrence of two very unusual dinoflagellate taphofacies, one developed in bituminous shales and the other in micrites, from the Oligocene fossil Lagerstätte at Sieblos, Hesse, Germany. A new dinoflagellate taxon, Sieblososphaera martini sp. nov. has been identified through analysis of dissociated skeletal elements in the bituminous shales and external moulds and casts in the micrites. The unique preservation of these fossils confirms them not only as primary biogenically silicified motile thecate cells, but also indicates that there was a much greater range of tabulation present within the subfamily Lithoperidiniaceae than has hitherto been recognized.