Cytogenetics of human oocytes,zygotes, and embryos after in vitro fertilization

Summary Chromosome errors, inherited or arising de novo during gametogenesis and transmitted at fertilization to the conceptus, may be a major cause of embryonic mortality. The in vitro fertilization and embryo transfer (IVF/ET) procedure provides extra material — oo-cytes, zygotes, and embryos — to investigate the contribution of chromosomal abnormality to implantation failure. This paper reviews the results of cytogenetic studies on such material. Estimates from a total of 1120 oocytes from 11 studies give an overall proportion of chromosomal abnormality of 35%. Single and multiple nullisomies and disomies are found, involving nonrandom chromosome gain or loss. Hypohaploid complements are more frequent than hyperhaploid complements. The higher rate of chromosome loss of hypohaploid karyotypes was found to be largely artifactual. The estimated overall frequency of aneuploidy is 13%. In embryos the level of chromosomal abnormality is 23%–40%. Errors of fertilization are responsible for a substantial number of triploid embryos, many of which develop into mosaics. Factors extrinsic to the conceptus, such as infertility, advanced maternal age, and ovarian hyperstimulation, may increase the level of chromosomal abnormality. More refined methods for accurately recognizing and selecting chromosomally normal embryos for transfer are needed to improve the success rate of this reproductive technology.     

Variants of the anti-Müllerian hormone gene in a compound heterozygote with the persistent Müllerian duct syndrome and his family

Summary The human genome contains a large number of interspersed simple repeat sequences that are variable in length and can therefore serve as highly informative, polymorphic markers. Typing procedures include conventional multilocus and single locus probing, and polymerase chain reaction aided analysis. We have identified simple sequences in a cosmid clone stemming from the human Y chromosome and consisting of (gata)_n repeats. We have compared these with two equivalent simple repeat loci from chromosome 12. After amplifying the tandemly repeated motifs, we detected between four and eight different alleles at each of the three loci. Codominant inheritance of the alleles was established in family studies and the informativity of the simple repeat loci was determined by typing unrelated individuals. The polymorphisms are suitable for application in linkage studies, practical forensic case work, deficiency cases in paternity determination, and for studying ethnological questions. The mutational mechanisms that bring about changes in simple repeats located both on the autosomes and on the sex chromosomes, are discussed.Professor Dr. Otto Prokop (Humboldt-Universität Berlin) on the occasion of his 70th birthday     

Long term regulation of nucleoside transport by thyroid hormone (T3) in cultured chromaffin cells

The adenosine transport in cultured chromaffin cells was increased by the presence of triiodo-l-thyronine (T₃) throughout the prolonged period studied. The V_max values of this transport obtained in absence and presence of 1 M T₃ were 36.21±2.1 and 44.17±3.5 (means±SD) pmol/10⁶cells/min respectively for 26 hours incubation-time with the hormone. The K_m values were not significantly modified. The number of adenosine transporters in cultured chromaffin cells, measured by [³H]nitrobenzylthioinosine (NBTI) binding, was increased by 1 M T₃ for 26 hours incubation-time. The values of binding sites per cell were 33,500±3,000 and 40,153±3,700 in absence and presence of T₃ respectively, without changing the K_d constant. When the transport studies were carried out in presence of cycloheximide, an inhibitor of protein synthesis, the adenosine transport capacity decreased with a half-life values of 23.9±2.8 and 24.3±2.1 hours both in the presence or absence of T₃ respectively. When cells were incubated in the presence of both T₃ and cycloheximide, not only the activatory effect of T₃ was completely abolished but also adenosine transport was decreased to the same extent as with cycloheximide alone. These results indicated that T₃ activation of adenosine transport in chromaffin cells required the protein-synthesizing mechanism.     

A continuous-culture approach to the question of inorganic carbon concentration by Synechococcus species

Abstract Chemostat cultures of Synechococcus PCC7942 were established in steady state over ten generations with inorganic carbon-limiting biomass production. The bicarbonate-concentration process was not significantly induced; RuBisCo activity was increased six-fold with decreasing dissolved inorganic carbon concentration and the presence of the 42-kDa cytoplasmic membrane polypeptide was observed but not implicated in the process.     

Occurrence of a capsule in Aeromonas salmonicida

Aeromonas salmonicida grown in a medium with excess glucose as carbon source produces both capsular and exocellular polysaccharides. The capsular polysaccharide is composed of glucose, mannose, rhamnose, N-acetylmannosamine and mannuronic acid in the molar ratios of approximately 5:3:0.75:2:1. The extracellular polysaccharide is similarly constituted, but in the molar ratios of approximately 4.75:10.5:1.5:2:1. The capsular and exocellular polysaccharides did not cross-react with monoclonal antibodies against the A-layer or the O-antigen lipopolysaccharide.     

The ovary ofCatajapyx aquilonaris (Insecta,Entognatha): ultrastructure of germarium and terminal filament

Summary Each of the two ovaries ofCatajapyx aquilonaris is composed of seven segmentally (metamerically) arranged ovarioles. The two lateral oviducts that join and bear ovarioles extend throughout the abdomen. In the ovariole three regions can be recognized: the terminal filament, the germarium and the vitellarium. The terminal filaments do not fuse with each other but attach separately (by means of muscle fibres) to the closest lobes of the fat body. Germ cells in the germarium are not joined by intercellular bridges and do not form clusters. Thus the ovarioles ofC. aquilonaris are interpreted as being primarily panoistic. The results obtained support the hypothesis that both dipluran subgroups (Campodeina and Japygina) do not form a monophyletic unit.     

Development of fertilized ovules and their role in the growth of the pea pod

The histological development of fertilized ovules during fruit-set and development in pea ( Pisum sativum L. cv. Alaska) has been investigated. Killing the ovules on day 0 (anthesis) or day 1 prevented fruit-set and resulted in ovary degeneration. When the ovules were destroyed at later stages the ovaries developed, though the rate of growth of the pod was reduced significantly. Pollination in pea occurs normally the day before anthesis, and fertilization of the egg cell 32 to 48 h later. The first divisions of the zygote and endosperm nuclei started simultaneously (ca 48 h after pollination) but the endosperm developed more rapidly than the embryo; the embryo sac cavity was lined with free endosperm nuclei at the time of beginning suspensor elongation. Extracts of endosperm and ovule coats from ovules at day 7 after anthesis showed fruit-set activity in pea, the latter material having about 3 times more activity than the former per ovule basis. These results indicate that fertilization of the ovule is necessary for fruit-set in pea, and that compounds which induce fruit-set are probably synthesized in the ovules following fertilization.     

Nutrient transfer between the root zones of soybean and maize plants connected by a common mycorrhizal mycelium

The objective of the study was to determine whether nutrient fluxes mediated by hyphae of vesicular-arbuscular mycorrhizal (VAM) fungi between the root zones of grass and legume plants differ with the legume's mode of N nutrition. The plants, nodulating or nonnodulating isolines of soybean [ Glycine max (L.) Merr.], were grown in association with a dwarf maize ( Zea mays L.) cultivar in containers which interposed a 6-cm-wide root-free soil bridge between legume and grass container compartments. The bridge was delimited by screens (44 μm) which permitted the passage of hyphae, but not of roots and minimized non VAM interactions between the plants. All plants were colonized by the VAM fungus Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe. The effects of N input to N-sufficient soybean plants through N₂-fixation or N-fertilization on associated maize-plant growth and nutrition were compared to those of an N-deficient (nonnodulating, unfertilized) soybean control. Maize, when associated with the N-fertilized soybean, increased 19% in biomass, 67% in N content and 77% in leaf N concentration relative to the maize plants of the N-deficient association. When maize was grown with nodulated soybean, maize N content increased by 22%, biomass did not change, but P content declined by 16%. Spore production by the VAM fungus was greatest in the soils of both plants of the N-fertilized treatment. The patterns of N and P distribution, as well as those of the other essential elements, indicated that association with the N-fertilized soybean plants was more advantageous to maize than was association with the N₂-fixing ones.     

Social context and reaction to separation in peer-reared pigtail macaques: Some preliminary observations

The social environment affects both behavioral and physiological responses to separation from the mother. Less information is available on the impact of the social environment on the response to separation in peer-reared infant monkeys. This study reports the responses of peer-reared pigtail macaque infants to repeated separations, and the impact of social versus isolation housing during the separation. The responses of two pairs of monkeys were studied during four three-day separations. One of each pair was housed in isolation during the separation, and the other was with another pair of peers, with whom they had been living for one month prior to the separation. The isolation-housed peer responded to the separation with behavioral agitation, but no depression. The socially-housed peer's behavior did not differ from baseline during the separation. During successive reunions, all the separated monkeys, regardless of housing condition, exhibited declining levels of behaviors related to maintaining proximity to their attachment figure. Although the number of subjects is small, the results suggest that the presence of social support, in the form of a familiar peer, can ameliorate the response to separation, and that with repeated separations the responses of the monkeys changes significantly.     

Enzymatic hydrolysis of 2,2,2,-trifluoroethyl α-chloro-α-phenylacetate in organic media

Summary 2,2,2-Trifluoroethyl -chloro--phenylacetate is succesfully hydrolysed in organic solvent in the presence of aniline andCandida cylindracea orPseudomonas cepacia lipase as catalysts.