Establishment of in vitro spermatogenesis from spermatocytes in the medaka, Oryzias latipes

Spermatocytes of the teleost, Oryzias latipes , at meiotic prophase were cultured without contact with somatic cells. They began to divide, progressing through the meiotic divisions and differentiating into round spermatids within 48 h. The chromosome number in both the primary and secondary spermatocytes at metaphase was n = 24. In spermatids, a single flagellum was formed and the release of residual bodies was observed in vitro . The size and shape of the flagellum were the same as those seen in vivo . The expression of protamine mRNA was detected in round spermatids. This result suggests that gene expression, as well as morphological change, is regulated by the progression of spermatogenesis in cell culture. Furthermore, when the eggs of O. latipes were inseminated with germ cells cultured for 10 days, normal embryos developed and hatched out. These results suggest that the spermatocytes of O. latipes develop into fertile sperm in cell culture.     

A review on disease transmission studies in relationship to production of embryos by in vitro fertilization and to related new reproductive technologies

This paper addresses the circumstances of germplasm contamination and updates on transmission of pathogenic agents by embryos produced in vitro and by associated techniques. It has been shown that some pathogenic agents might have been associated with the follicular oocytes and oviductal cells, collected for in vitro fertilization (IVF), resulting in infected embryos. Experimental introduction of pathogenic agent with oocytes or infected semen into the IVF system allows, in most cases, for the fertilization of eggs and for the production of some transferable quality embryos. Rendering of oocytes and embryos free of infectious pathogens, using the standard sequential washing or enzymatic treatment, is inconsistent and more difficult in the presently used in vitro fertilization system as compared to in vivo produced embryos.     

IN VITRO FERTILIZATION OF IN VITRO MATURED MINKE WHALE (BALAENOPTERA ACUTOROSTRATA) FOLLICULAR OOCYTES

In vitro fertilization of follicular oocytes harvested from ovaries and matured in vitro was attempted for 55 minke whales ( Balaenoptera acutorostrata ) captured for Japanese research purposes in the Antarctic Ocean during the period from November 1995 to March 1996. In Experiment 1, effects of culture duration (96 h or 120 h) on maturation of follicular oocytes and addition of caffeine (5 mM) and/or heparin (100 pg/ml) on sperm penetration and pro-nuclear formation were investigated. Spermatozoa recovered from the vasa deferentia of four mature males were diluted (5-fold) and frozen at - 80°C. The post-thawed and pooled spermatozoa were used for in vitro insemination. A higher ( P < 0.05) proportion of the oocytes cultured for 120 h (34.2% of 260) progressed beyond the second metaphase stage than of the oocytes cultured for 96 h (26.0% of 262). For the matured oocytes, higher rates of penetration ( P < 0.05) and pronuclear formation ( P < 0.01) were obtained in the oocytes cultured for 120 h (55.1% and 40.4%) than in those cultured for 96 h (32.4 % and 20.6%). Addition of caffeine and heparin did not show a significant effect. In Experiment 2, follicular oocytes matured for 120 h and then inseminated were cultured to examine the subsequent development in two culture systems (with and without co-cultured cumulus cells). Of 448 inseminated oocytes, cleaved embryos (2–16 cells) were observed with (5.8%) and without (4.9%) co-cultured systems. No cleavage was observed in 54 ova without insemination. These results indicate that in vitro fertilization of minke whale in vitro matured follicular oocytes with cryopreserved spermatozoa is possible, yielding cleaved embryos.     

Cell division patterns in the apices of subterranean axis and aerial shoot of Psilotum nudum (Psilotaceae): morphological and phylogenetic implications for the subterranean axis

The cell division pattern in the apical meristem of Psilotum nudum was examined using epi-illumination microscopy and a paraffin method. In the subterranean axis, about half of the derivative cells of the apical cell produce tetrahedral daughter apical cells by the first three or more oblique divisions. Roughly half of these apical cells give rise to the apical meristems of axes, whereas the other half do not. Various relative activities of the mother and daughter apical cells give rise to disordered branching patterns. In the ill-organized apical meristem as well as the leafless and capless structure, the Psilotum subterranean axis differs from the basic organs of vascular plants such as stem and root and seems to be an independent organ. The cell division pattern characteristic of the subterranean axis persists in the young unbranched aerial shoots, although fewer daughter apical cells are produced. Dichotomous branching of the aerial shoots, as in a variety of organs of pteridophytes, involves loss of the mother apical cell followed by appearance of two daughter apical cells.     

Peroxidase isoenzymes in normal and habituated calli of sugar beet during transfer from light to darkness

Habituated sugar beet calli have been characterized as having a deficiency in some tetrapyrrole containing compounds. However, peroxidases might be dissociated from the other tetrapyrrole containing compounds. When light-cultured normal and habituated calli were transferred to darkness their peroxidase activity reduced and increased, respectively, indicating that habituation could not strictly be characterized by a deficiency in peroxidase content but rather by a different regulation of its activity. This regulation could be mediated through soluble effectors which act as potential peroxidase inhibitors and/or by a differential expression of the peroxidase isoenzyme patterns which were present in these tissues in both light and darkness. The different peroxidase activity and the nature of acidic and basic peroxidase isoenzymes in normal and habituated tissues could explain the different features of both types of cultures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Calcium distribution in fertilized and unfertilized ovules and embryo sacs of Nicotiana tabacum L.

Potassium antimonate was used to localize Ca²⁺ in tobacco ovules from 0 to 7 d after anthesis in pollinated and emasculated flowers. Antimonate binds “loosely bound” Ca²⁺ into calcium antimonate; less-soluble forms are unavailable and free calcium usually escapes. Ovules are immature at anthesis. Abundant calcium precipitates in nucellar cells surrounding the micropylar canal. A difference between calcium in the two synergids emerges at 1 d, which is enhanced in pollinated flowers. The future receptive synergid accumulates more precipitates in the nucleus, cytoplasm and cell walls. After fertilization, micropyle precipitates diminish, and the ovule is unreceptive to further tube entry. In emasculated flowers 6 d after anthesis, ovular precipitates essentially disappear; however, flowers pollinated at 4–5 d and collected 2 d later largely restore their prior concentration of precipitates. Ovular precipitates occur initially in the nucellus, then the embryo sac, and finally the synergid and micropylar filiform apparatus. Possibility, calcium is released from the embryo sac, although no structural evidence of exudate formation was observed. Calcium precipitates in the ovule correlate with the ability of the ovule to be fertilized, suggesting that successful pollen tube entry and later development may require calcium of the class precipitated by antimonate. Received: 14 August 1996 / Accepted: 9 October 1996     

Statistical analysis of spatial patterns of the heliozoanActinophrys sol

Summary Cell-to-cell interaction and spatial distribution of the heliozoanActinophrys sol was analyzed with computer-aided video microscopy. By means of goodness-of-fit statistics (² analysis) and a quadrat-count analysis (I-curve analysis), the spatial point pattern of the cells was shown to be of regular distribution, which implies that a regulating mechanism is operating to encourage an even spatial distribution of the cell centers ofActinophrys. An attempt was further made to define a unified model which fitsActinophrys cell distribution observed at different cell densities. For this purpose, the fitting of a parameterized potential function (r)=(/r)¹² was carried out, wherer is the distance between cell centers of two neighboring cells. The scaling parameter a was estimated from the maximum likelihood procedure for obtaining the best fit for the data, which was found to be a decreasing function of the cell density; we obtained = 0.44 mm at a low cell density (0.5 cell/mm²) and =0.10 mm at the highest cell density (6.5 cells/mm²). These results suggest that (1) the possible nearest distance between two neighboring cells is primarily defined by the axopodial length, and (2) at lower cell densities,Actinophrys can recognize the presence of distant neighboring cells by some unknown means.     

The relationship between eyespot shape and wing shape in the butterfly Bicyclus anynana: A genetic and morphometrical approach

The African butterfly, Bicyclus anynana, normally possesses circular eyespots on its wings. Artificial selection lines, which express ellipsoidal eyespots on the dorsal surface of the forewing, were used to investigate correlated changes in wing shape. Morphometric analysis of linear wing measurements and wing scale counts provided evidence that eyespot shape was correlated with localised shape changes in the corresponding wing-cell, with overall shape changes in the wing, and with the density/arrangement of scales around the eyespot area.     

The Ultrastructure of Zosterodasys agamalievi (Ciliophora: Synhymeniida)

ABSTRACT. The cell surface of the synhymeniid ciliate, Zosterodasys agamalievi , consists of shallow kinetal grooves separated by low cortical ridges. Numerous electron-opaque bodies are located in the cortical ridges, inside the kinetal grooves, and are distributed in parallel rows between adjacent kineties. Well-developed alveoli are present beneath the cell surface membrane. Zosterodasys agamalievi has a single micronucleus and a homomerous macronucleus. The infraciliature of the somatic monokinetid consists of an anteriorly-directed kinetodesmal fiber, a well-developed divergent postciliary microtubular ribbon, radially-oriented transverse microtubules, and a short striated rootlet, which extends anteriorly from the base of the kinetosome into the cell. Zosterodasys agamalievi has a perioral band of paired cilia, the synhymenium, that winds obliquely across the ventral surface of the body, just posterior to the cytostome. The infraciliature of the anterior kinetosome of the synhymenium consists of two postciliary microtubules; a well-developed, divergent post-ciliary ribbon of microtubules and a short kinetodesmal fiber are associated with the posterior kinetosome. The cytopharynx is supported by 14-16 nematodesmata which are capped distally by a capitulum. The cytopharynx is bound proximally by a fibrous sheath and is lined by radially-arranged microtubular ribbons. No obvious oral ciliature is present.     

合理化防的马尾松林动物和虫生真菌群落的数量时空格局

对马尾松纯林中动物和虫生真菌群落的调查表明 ,植食性、捕食性、寄生性昆虫和蜘蛛类群物种数分别占 51 %、1 2 %、7%和 2 6% ,益害生物个体数之比约 1∶ 1 0 .2个相似的林分或林间层次中 ,物种数、科数相等或相近 ,优势目相同 ,而且二者的植食性、捕食性、寄生性昆虫和蜘蛛类群的物种数和个体数的波动相对应地趋于一致 .主成分分析显示群落 1周年内处于“深秋准备越冬→冬眠→早春复苏→春、夏、初秋繁荣”的循环演替之中 ,其自我调节力和稳定性较强