Biometry, and fatty acid and fatty alcohol composition of the Arctic ctenophore Mertensia ovum from Kongsfjorden

Lipids of the Arctic ctenophore Mertensia ovum, collected from Kongsfjorden (Svalbard) in 2001, were analysed to investigate seasonal variability and fate of dietary lipids. Total lipids, lipid classes and fatty acid and alcohol compositions were determined in animals, which were selected according to age-group and season. Changes in lipids of age-group 0 animals were followed during growth from spring to autumn. Total lipids increased from May to September. Lipids as percentage of dry mass were lowest in August indicating their use for reproduction. Higher values occurred in September, which may be due to lipid storage for overwintering. Wax esters were the major lipid class accounting for about 50% of total lipids in age-group 0 animals from July and August. Phospholipids were the second largest lipid fraction with up to 46% in this age-group. The principal fatty acids of M. ovum from all age-groups were 22:6(n-3), 20:5(n-3) and 16:0. Wax ester fatty alcohols were dominated by 22:1(n-11) and 20:1(n-9) followed by moderate proportions of 16:0. The unique feature of M. ovum lipids was the high amount of free fatty alcohols originating probably from the dietary wax esters. In May, free alcohols exhibited the highest mean proportion with 14.6% in age-group 0 animals. We present the first data describing a detailed free fatty alcohol composition in zooplankton. This composition was very different from the alcohol composition of M. ovum wax esters because of the predominance of the long-chain monounsaturated 22:1 (n-11) alcohol accounting for almost 100% of total free alcohols in some samples. The detailed lipid composition clearly reflected feeding of M. ovum on the herbivorous calanoid species, Calanus glacialis and C. finmarchicus, the abundant members of the zooplankton community in Kongsfjorden. Other copepod species or prey items seem to be less important for M. ovum.

Concerning, earliest first growth in the human ovum;

Mode of access: Internet.

The role of pollen in the changing environmental conditions of Scots pine

Rapid change in climate is challenge for the adaptation of forest trees in the future. In wind pollinated tree species pollen mediated long distance gene flow may provide alleles that are (pre)adapted to a future climate. In order to examine the long distance pollen flow in Scots pine (Pinus sylvestris L.), we measured the amount and viability of airborne pollen and flowering phenology in central, northern, and northernmost Finland during four years. Viable airborne pollen grains were detected during female flowering and before local pollen shedding in all study sites. The situation when there was nonlocal pollen in the air lasted from one to four days depending on the year and study site. The amount of nonlocal airborne pollen varied also between years and study sites, the total amount of nonlocal viable pollen in the air was 2.3% from all detected viable pollen grains. The effect of pollen origin on seeds siring ability was studied with artificial pollination experiments. Pollen genotypes originating from southern Finland sired 76% and 48 % of the analysed seeds in competition studies where both pollen origin were introduced simultaneously into the female strobili. We examined the importance of arrival order of pollen grains in to the strobili in a study where pollen genotypes of different origin were introduced in two hours interval. Northern genotypes sired 76% of the analysed seeds when it was injected first, but in the "southern first" experiment both pollen types sired equal amount of seeds. The first pollen grain in the pollen chamber do not always fertilizes the ovum, instead there likely is more complex way of competition between pollen grains. To examine chemically mediated pollen-pollen interactions we conducted in vitro germination experiment where different pollen genotypes had chemical but not physical contact. Both positive and negative effects of interactions were found. We found highly negative effects in germinability of northern pollen grains when they were germinating with southern pollen, and increase in the germinability of southern pollen. There were no variation in the size of the dry pollen grains between pollen origins, and minor variation between different genotypes. After hydration and germination northern pollen grains were larger than southern pollen. Pollen genotypes having high hydration rates had low germinability and tube growth rate, however, germinated pollen grains were larger in size than nongerminated. This supports the suggestion that the early germination and growth of pollen tube is dependent on pollen storage materialsand less dependent on water intake and hydration. Long distance pollen movements and good competition ability of southern pollen makes gene flow possible, although rising temperature and timing of pollen movements may affect pollen competition and the amount of gene flow.

Técnicas de tratamiento de la esterilidad : aspectos tecnológicos y éticos abordados en el Informe Warnock

El Informe Warnock aborda parte de los problemas que surgen a partir del diagnóstico de esterilidad, tanto para los individuos como para toda la sociedad. Justifica el recurso de técnicas para solucionar la imposibilidad de concebir. Se describen los distintos procedimientos dando las recomendaciones para cada una de las técnicas empleadas hasta el momento: inseminación artificial (homóloga y heteróloga), fecundación in vitro, donación de óvulos y embriones, útero subrogado. Aborda el uso extendido de las técnicas de tratamiento de la esterilidad para otros fines: evitar la transmisión de enfermedades hereditarias y selección de sexo. Asimismo, realiza sugerencias para una práctica correcta en todos los procedimientos y propone seguimientos y revisiones. En paralelo al análisis exhaustivo de la Comisión Warnock, se actualizan los datos procedimentales, evaluando los aspectos éticos y la eficiencia de algunas técnicas.

Hermaphroditism in some marine animals

Hermaphroditism, a phenomenon in which one and the same individual produces sperms, the male gamate the ovum, the female gamate, is generally common in plants and lower animals and hence is considered as a primitive character. However, it is rare in higher invertebrates such as insects, spiders, prawns and also in the lower vertebrates to which fishes belong. Prawns and fishes have highly evolved reproductive systems and occur as separate individuals of males and females. Both these groups do have some species which are regurarly hermaphrodites and others which are teratologically hermaphrodites.

高产奶牛连续活体采卵及卵母细胞体外受精研究

在超声波扫描仪的指导下,用双孔型采卵针以11.3～12.0kPa抽吸压经阴道对8头高产奶牛分别连续实施7次活体采卵,每4d1次,共采集卵子340个,占可见卵泡数的53.5%.每次头均采集卵子6.1个.卵子经过体外培养、体外受精、体外受精胚体外发育培养,于体外受精后48h、168h统计的卵裂率、囊胚发育率分别为75.0%和29.7%.研究结果表明,在超声波扫描仪指导下对奶牛连续进行活体采卵,将所得卵子进行体外成熟、体外受精、体外培养,在生产中是可行的.

Development of zona-free hamster ova to blastocysts in vitro

The zona pellucida (ZP) enclosing the mammalian ovum is important for its protection and for initial stages of fertilization, but the role of the ZP during embryo development is less clear. This study was designed to investigate if the hamster ZP is needed for embryo development from 1-cell to blastocyst in vitro, and to compare methods for removing the ZP. A total of 395 hamster pronucleate ova were collected 10 h post activation from superovulated, mated female hamsters. The ZP was removed from some ova using either 0.05% pronase, 0.05% trypsin or acid Tyrode's solution. To prevent ZP-free ova from sticking together, they were cultured singly in 30-50 muL drops of HECM-6 culture medium together with ZP-intact ova as controls. There was no significant difference among treatment groups in embryo development to blastocyst: 36/87 (42%) in the ZP intact group; 35/75 (47%) in the pronase-treated ZP-free group; 37/74 (50%) in the trypsin-treated ZP-free group; and 37/71 (52%) in the acid-treated ZP-free group. These results indicate that 1) the ZP is unnecessary for hamster embryo development in vitro from the pronucleate ovum stage to blastocyst; 2) none of the three ZP-removal methods was detrimental to embryo development; 3) embryos do not need to be cultured in groups during in vitro development from 1-cell to blastocyst. (C) 2000 by Elsevier Science Inc.

Identification of a novel gene K23 over-expressed in fish cross-subfamily cloned embryos

A novel gene-K23, differentially expressed in cross-subfamily cloned embryos, was isolated by RACE-PCR technique. It had 2580 base pairs (bp) in length, with a 1,425 bp open reading frame (ORF) encoding a putative protein of 474 amino acids (aa). Bioinformatic analysis indicated that K23 had 22 phosphorylation sites, but it had no signal peptides. Developmental expression analysis in zebrafish showed that K23 transcripts were maternally expressed in ovum and the amount of K23 transcripts increased gradually from zygote to pharyngula period. Subcellular localization analysis revealed that K23 protein was homogeneously distributed both in nuclei and cytoplasm. Taken together, our findings indicate that K23 gene is a novel gene differentially expressed in fish cross-subfamily cloned embryos.

The precocious Chinese mitten crab: Changes of gonad, survival rate, and life span in a freshwater lake

Changes of the gonad. survival rate, and life span of the precocious (i.e., sexually mature in their first October-November, at the age of 5 or 6 months) Chinese mitten crab (Eriocheir sinensis) were studied in a small, shallow, macrophytic, freshwater lake along the middle reaches of the Changjiang River, China. The gonosomatic index (GSI) reached peak during the next March when the female GSI was 12.32 +/- 1.75 SD% and the male GSI A as 4.24 +/- 0.19%. The sexual glands degraded from then on. In the first ten-day period of the following July, there was no complete ovum in the ovary. and the sperm became thin and lost adhesion. The population declined sharply from November to July, and the last one (a female) died in the middle of July, which indicated that the life span of the precocious crab was about 12 months (from larval hatching in June to death in July of next year). The survival curve might be expressed as Y = 1.09exp(-0.018x) (Y survival rate; x: days) for the precocious crabs stocked in experimental cages.

Wee1-regulated apoptosis mediated by the crk adaptor protein in Xenopus egg extracts.

Many of the biochemical reactions of apoptotic cell death, including mitochondrial cytochrome c release and caspase activation, can be reconstituted in cell-free extracts derived from Xenopus eggs. In addition, because caspase activation does not occur until the egg extract has been incubated for several hours on the bench, upstream signaling processes occurring before full apoptosis are rendered accessible to biochemical manipulation. We reported previously that the adaptor protein Crk is required for apoptotic signaling in egg extracts (Evans, E.K., W. Lu, S.L. Strum, B.J. Mayer, and S. Kornbluth. 1997. EMBO (Eur. Mol. Biol. Organ.) J. 16:230-241). Moreover, we demonstrated that removal of Crk Src homology (SH)2 or SH3 interactors from the extracts prevented apoptosis. We now report the finding that the relevant Crk SH2-interacting protein, important for apoptotic signaling in the extract, is the well-known cell cycle regulator, Wee1. We have demonstrated a specific interaction between tyrosine-phosphorylated Wee1 and the Crk SH2 domain and have shown that recombinant Wee1 can restore apoptosis to an extract depleted of SH2 interactors. Moreover, exogenous Wee1 accelerated apoptosis in egg extracts, and this acceleration was largely dependent on the presence of endogenous Crk protein. As other Cdk inhibitors, such as roscovitine and Myt1, did not act like Wee1 to accelerate apoptosis, we propose that Wee1-Crk complexes signal in a novel apoptotic pathway, which may be unrelated to Wee1's role as a cell cycle regulator.

Control of Emi2 activity and stability through Mos-mediated recruitment of PP2A.

Before fertilization, vertebrate eggs are arrested in meiosis II by cytostatic factor (CSF), which holds the anaphase-promoting complex (APC) in an inactive state. It was recently reported that Mos, an integral component of CSF, acts in part by promoting the Rsk-mediated phosphorylation of the APC inhibitor Emi2/Erp1. We report here that Rsk phosphorylation of Emi2 promotes its interaction with the protein phosphatase PP2A. Emi2 residues adjacent to the Rsk phosphorylation site were important for PP2A binding. An Emi2 mutant that retained Rsk phosphorylation but lacked PP2A binding could not be modulated by Mos. PP2A bound to Emi2 acted on two distinct clusters of sites phosphorylated by Cdc2, one responsible for modulating its stability during CSF arrest and one that controls binding to the APC. These findings provide a molecular mechanism for Mos action in promoting CSF arrest and also define an unusual mechanism, whereby protein phosphorylation recruits a phosphatase for dephosphorylation of distinct sites phosphorylated by another kinase.

Long-duration animal tracking in difficult lighting conditions.

High-throughput analysis of animal behavior requires software to analyze videos. Such software typically depends on the experiments' being performed in good lighting conditions, but this ideal is difficult or impossible to achieve for certain classes of experiments. Here, we describe techniques that allow long-duration positional tracking in difficult lighting conditions with strong shadows or recurring "on"/"off" changes in lighting. The latter condition will likely become increasingly common, e.g., for Drosophila due to the advent of red-shifted channel rhodopsins. The techniques enabled tracking with good accuracy in three types of experiments with difficult lighting conditions in our lab. Our technique handling shadows relies on single-animal tracking and on shadows' and flies' being accurately distinguishable by distance to the center of the arena (or a similar geometric rule); the other techniques should be broadly applicable. We implemented the techniques as extensions of the widely-used tracking software Ctrax; however, they are relatively simple, not specific to Drosophila, and could be added to other trackers as well.

Ribonucleic acid metabolism in unfertilized and fertilized sea-urchin eggs.

Journal Article

Fasciola hepatica:the effect of the microfilament inhibitor cytochalasin B on the ultrastructure of the adult fluke

The effect of the microfilament inhibitor cytochalasin B (10 and 100 micrograms/ml) on the ultrastructure of adult Fasciola hepatica was determined in vitro by scanning and transmission electron microscopy (SEM, TEM) using both intact flukes and tissue-slice material. SEM revealed that initial swelling of the tegument led to surface blebbing and limited areas of sloughing after 24 h treatment at 100 micrograms/ml. In the tegumental syncytium, basal accumulations of secretory bodies (especially T2s) were evident in the earlier time periods but declined with longer incubations, until few secretory bodies remained in the syncytium overall. Blebbing of the apical plasma membrane and occasional areas of breakdown and sloughing of the tegument were observed over longer periods of treatment at 100 micrograms/ml. In the tegumental cell bodies, the Golgi complexes gradually decreased in size and activity, and few secretory bodies were produced. In the later time periods, the cells assumed abnormal shapes, the cytoplasm shrinking in towards the nucleus. In the vitelline follicles, a random dispersion of shell protein globules was evident within the intermediate-type cells, rather than their being organized into distinct shell globule clusters. Disruption of this process was more severe at the higher concentration of 100 micrograms/ml and again was more evident in tissue-slice material. In the latter, after prolonged (12 h) exposure to cytochalasin B, the intermediate and mature vitelline cells were filled with loosely packed and expanded shell globule clusters, containing few shell protein globules. The mature vitelline cells continued to lay down "yolk" globules and glycogen deposits. Disruption of the network of processes from the nurse cells was evident at the higher concentration of cytochalasin. Spaces began to appear between the vitelline cells and grew larger with progressively longer incubation periods, and the cells themselves assumed abnormal shapes. A number of binucleate stem cells were observed in tissue-slice material at the longest incubation period (12 h).