Extracellular Neuroactive Amino Acids in the Rat Striatum During Ischaemia: Comparison Between Penumbral Conditions and Ischaemia with Sustained Anoxic Depolarisation

Abstract: Changes in the extracellular levels of excitatory and inhibitory amino acid transmitters were studied in the rat striatum during penumbral ischaemia using intracerebral microdialysis. Effects of penumbral forebrain ischaemia were compared with those of ischaemia with sustained anoxic depolarisation and K⁺ (100 m M ). Comparisons were also made between different groups of animals at 2 and 24 h after dialysis probe implantation. The K⁺ stimulus did not provoke any release of excitatory amino acids in the 24-h group, probably reflecting a decrease of functional synapses adjacent to the probe. During 30 min of penumbral ischaemia, excitatory amino acids did not reach critical concentrations in the extracellular fluid, and increases in levels of inhibitory/modulatory amino acids were similar. On the other hand, severe transient ischaemia resulted in massive synchronous release of many neuroactive excitatory and inhibitory compounds, in both the 2- and 24-h groups. These and other data suggest that changes during severe ischaemia may arise from both neurotransmitter and metabolic pools. It is concluded that is- chaemic damage in the penumbra may not be related to extracellular neuroactive amino acid changes generated within this region.     

Integration is essential for efficient gene expression of human immunodeficiency virus type 1.

A mutant of human immunodeficiency virus type 1 which carries a frameshift insertion in the integrase/endonuclease region of pol gene was constructed in vitro. Upon transfection into cells, although this mutant exhibited a normal phenotype with respect to expression of gag, pol, and env genes and to generation of progeny virions, no replication-competent virus in CD4-positive cells emerged. An assay for the single-step replication of a defective viral genome dependent on trans complementation by rev protein was established and used to monitor the early phase of viral infection process. Viral clones with a mutation in the vif, vpr, or vpu gene displayed no abnormality in the early phase. In contrast, the integrase mutant did not direct a marker gene expression after infection. Together with an observation that the mutant lacked the ability to integrate, these results indicated that the integration was required for efficient viral gene expression and productive infection of human immunodeficiency virus type 1.     

Individual DNA identification from ancient human remains.

Individual identification of ancient human remains is one of the most fundamental requisites for studies of paleo-population genetics, including kinship among ancient people, intra- and interpopulation structures in ancient times, and the origin of human populations. However, knowledge of these subjects has been based mainly on circumstantial archaeological evidence for kinship and intrapopulation structure and on genetic studies of modern human populations. Here we describe individual identification of ancient humans by using short-nucleotide tandem repeats and mtDNAs as genetic markers. The application of this approach to kinship analysis shows clearly the presence or absence of kinship among the ancient remains examined.     

Osteological and histological comparison of the development of the interphalangeal intercalary skeletal element between hyloid and ranoid anurans

Some frog species have a unique skeletal element, referred to as the intercalary element (IE), in the joints between the terminal and subterminal phalanges of all digits. IEs are composed of cartilage or connective tissue and have a markedly differ shape than the phalanges. IEs are highly related to the arboreal lifestyle and toe pads. The IE is found only in neobatrachian frogs among anurans, suggesting that it is a novelty of Neobatrachia. IEs are widely distributed among multiple neobatrachian lineages and are found in the suborders Hyloides and Ranoides (the two major clades in Neobatrachia). However, it is unclear whether the IEs found in multiple linages resulted from convergent evolution. Therefore, in this study, we aimed to examine how similar or different the developmental trajectories of the IEs are between Hyloides and Ranoides. To that end, we compared the osteological and histological developmental processes of the IEs of the hyloid frog Dryophytes japonicus and the ranoid frog Zhangixalus schlegelii. Both species shared the same IE-initiation site and level of tissue differentiation around the IE when it began to form in tadpoles, although the IE developments initiated at different stages which were determined by external criteria. These results suggest that similar mechanisms drive IE formation in the digits of both species, supporting the hypothesis that the IEs did not evolve convergently.     

Occurrence of a novel group of hemagglutinins extractable by Pronase treatment in marine algae

Nine species of marine algae have been assessed for the presence of novel hemagglutinins not extractable with buffer, unless the algal tissue was pretreated with Pronase. All species examined contained hemagglutinins, indicating the existence of a novel group of hemagglutinins which differed from those reported previously in marine algae.     

Cryopreservation of wild mouse spermatozoa

Spermatozoa of wild mice from China, Czechoslovakia, Denmark, India, Japan and Switzerland were frozen and stored at -196 degrees C. After thawing, intact oocytes were inseminated in vitro with relatively high motility frozen-thawed mouse spermatozoa from Czechoslovakia, Denmark and India, while oocytes with a partially dissected zona were inseminated with low motility frozen-thawed spermatozoa from China, Japan and Switzerland. Embryos developing to the 2-cell stage from oocytes fertilized with frozen-thawed spermatozoa were transferred to the oviducts of female recipients on the first day of pseudopregnancy (day when a vaginal plug was confirmed). Successful embryo development to the 2-cell stage was 46 to 67%. Offspring resulted from 17 to 51% of these transferred 2-cell embryos.     

DIVISION APPARATUS OF THE CHLOROPLAST IN NANNOCHLORIS BACILLARIS (CHLOROPHYTA)1

Chloroplast division in Nannochloris bacillaris Naumann (Chlorophyta) was examined by electron microscopy after preparation of samples by freeze-substitution. A pair of belts appeared on the surface of the outer and inner envelope membranes at the middle of the chloroplast. These belts seemed to be constructed of thin fibrils that run parallel to the longitudinal direction of the belts. The outer fibrillar belt increased in width as the constriction of the chloroplast advanced. It appears that the fibrillar belt is the division apparatus of the chloroplast. It encircles the chloroplast and finally divides the chloroplast in two as the diameter of the belt decreases.