On the occurrence and biology of some Antarctic Mysidacea (Crustacea)

Summary 10 species of Mysidacea were sampled during the Polarstern and Walther Herwig SIBEX cruises to the Antarctic Peninsula region from 1983 to 1986. The commonest were Antarctomysis maxima, A. ohlini and Mysidetes posthon. For these species the size and maturity stage composition as well as the length-weight relationships are given. The species considered are growing slowly and attain a long life span, M. posthon reached age class 3+, A. ohlini at least lived as long as 5 years, while A. maxima was found to be of age 5+ in the Peninsula area and probably 6+ in the Weddell Sea. The generation time of Antarctomysis species was 4 years and 3 years in Mysidetes posthon. Fecundity was low, mean number of offspring was about 13 for M. posthon and 21 for A. maxima. Rematuration was observed for the species A. maxima, indicating several spawning events during its life span. Biomass production is low for A. maxima, shown by a P/B-index of 0.98. Mortality of this species was estimated to be Z=1.1, which indicates that 33% of the specimens of an age group survive until the next year. The distribution and spatial separation of the two Antarctomysis species is discussed.     

Micronuclei in human lymphocytes irradiated in vitro or in vivo

Venous blood from healthy donors or from patients with various lympho- and myeloproliferative diseases was incubated in vitro in the presence of cytochalasin B for the induction of binucleated lymphocytes. The time at which cytochalasin B was added depended on the proliferation rate of the lymphocytes. Proliferation was monitored using a semiautomatic microscope photometer/computer system. The background level of micronuclei in binucleated lymphocytes of the patients before radiotherapy was statistically indistinguishable from that of healthy persons. Blood from both groups was irradiated in vitro for the study of the dose-response relationship. The dose-response curves were very similar up to 3.75 Gy, and a somewhat lower micronucleus frequency was found in lymphocytes of patients after a 5-Gy exposure. These in vitro results were compared with in vivo exposure after total-body irradiation of leukemic patients. Due to heavy medication that accompanied radiation therapy, only two doses (1.25 and 2.5 Gy) could be checked after in vivo exposure. There was no statistically significant difference between in vitro and in vivo results after 1.25 Gy, but a slightly lower number of micronuclei was observed after in vivo exposure to 2.5 Gy.     

Comparison of two cytochromes P-450 from Candida maltosa: primary structures, substrate specificities and effects of their expression in Saccharomyces cerevisiae on the proliferation of the endoplasmic reticulum

cDNAs were cloned, sequenced and expressed which encode two different cytochrome P-450 forms of the alkane-assimilating yeast Candida maltosa, designated as P-450Cm1 and P-450Cm2. The amino acid sequences deduced were about 55% identical. Expression in Saccharomyces cerevisiae resulted in the formation of intact microsomal P-450 systems catalyzing the hydroxylation of n-hexadecane and lauric acid with significantly different substrate preferences. A massive proliferation of the endoplasmic reticulum was observed in the S. cerevisiae cells which produced P-450. Depending on the P-450 form expressed, distinctly organized stacks of paired membranes appeared and occupied considerable areas of the cytoplasm. As shown by immunoelectron microscopy for P-450Cm1, the protein expressed was highly concentrated within these newly formed membrane structures.     

No evidence for linkage of autosomal dominant proximal spinal muscular atrophies to chromosome 5q markers

Summary Two recent articles have reported the linkage of a gene for recessive spinal muscular atrophy (SMA) on the chromosome region 5q11.2–13.3. Our data show no linkage of the dominantly inherited forms of SMA to this chromosome region.     

A small deletion and an adjacent base exchange in a potential stem-loop region of the neurofibromatosis 1 gene

Summary A single-strand conformational polymorphism found in the DNA of a patient with neurofibromatosis 1 (NF1) was shown to be caused by a deletion of a CCACC or CACCT sequence and an adjacent transversion, located about 500 base pairs downstream from the region that codes for a functional domain of the NF1 gene product. This mutation could also be detected in the patient and in his affected daughter by heteroduplex analysis. The deletion removes the proximal half of a small potential stem-loop and interrupts the reading frame in exon 1. A severely truncated protein with a grossly altered carboxy terminus lacking one third of its sequence is expected to be formed from the mutant allele.     

An endogenous ligand for the central sulfonylurea receptor

An endogenous ligand for the rat central sulfonylurea receptor has been evidenced in the rat central nervous system. The characteristics of this ligand (extractibility, non-dialysability, chromatographic behaviour on different media, sensitivity to proteases) indicate that it is a neutral to slightly basic peptide.     

Growth phase-dependent proteins of the Ehrlich ascites tumor analyzed by one- and two-dimensional electrophoresis

The decrease of the growth rate of the Ehrlich ascites tumor is correlated with changes in the de novo synthesis and abundance of several proteins as is shown by electrophoretic methods. The synthesis of a number of these growth-dependent proteins can be induced in vitro by incubation of the tumor cells in the presence of serum.