Genetic studies on nucleolus organizer regions (NORs) in cattle

Experimentally produced monozygotic twins, natural opposite sex blood chimeras (freemartins), and several pedigrees were used to evaluate the genetic influences on the nucleolus organizer region (NOR) patterns in cattle. In monozygotic twins, the NOR patterns of both twins are extremely similar. In chimeras, NOR patterns of genetically identical, peripheral blood lymphocytes (PBL) from the two partners resemble each other. In contrast, genetically different PBL (sib organ) differ significantly in the same environment. A high heritability of the individual NOR patterns is also demonstrated in our 23 pedigrees. In conclusion, our data demonstrate that variation in NOR expression is predominantly due to genetic factors.     

Localized insertion of new S-layer during growth of Bacillus stearothermophilus strains

Bacillus stearothermophilus strains PV 72 and ATCC 12980 carry a crystalline surface layer (S-layer) with hexagonal (p6) and oblique (p2) symmetry, respectively. Sites of insertions of new subunits into the regular lattice during cell growth have been determined by the indirect fluorescent antibody technique and the protein A/colloidal gold technique.During S-layer growth on both bacillus strains the following common features were noted: 1. shedding of intact S-layer or turnover of individual subunits was not seen; 2. new S-layer was deposited in helically-arranged bands over the cylindrical surface of the cell at a pitch angle related to the orientation of the lattice vectors of the crystalline array; 3. little or no S-layer was inserted into pre-existing S-layer at the poles, and 4. septal regions and, subsequently, newly formed cell poles were covered with new S-layer protein.     

Simultaneous modelling of distributional patterns in a guild of eastern-Australian cicadas

Summary The distributions, with respect to habitat structure, of nine species of eastern-Australian cicadas have been shown to be non-random. The most striking consequence of this non-randomness is a marked inverse relationship between habitat breadth and habitat position (terms defined in text). Eight basic models and 12 derived models were used in conjunction with a canonical space to try to account for the ways in which the species of cicadas were distributed with respect to habitat. Several models produced results that were in reasonable agreement with the observed data. The most parsimonious of these corresponds to analytical results of other workers, such as Diamond's (1975) incidence curves, occurrence sequences (Schoener and Schoener 1983), and probability functions (Adler and Wilson 1985). The distributions of cicadas can be modelled by assuming that the species occupy sites independently of one another. These species of cicadas are unlikely to engage in interspecific competition, which is consistent with independence of distributions.     

A free-radical hypothesis for the instability and evolution of genotype and phenotypein vitro

It has been known for several decades that cultured murine cells undergo a defined series of changes, i.e., anin vitro evolution, which includes crisis, spontaneous transformation (immortalization), aneuploidy, and spontaneous neoplastic transformation. These changes have been shown to be caused by thein vitro environment rather than an inherent instability of the murine phenotype or genotype. Serum amine oxidases were recently identified as a predominant cause of crisis. These enzymes generate hydrogen peroxide from polyamine substrates that enter the extracellular milieu. This finding implicates free-radical toxicity as the underlying cause ofin vitro evolution. We propose an oxyradical hypothesis to explain each of the stages ofin vitro evolution and discuss its significance for cytotechnology and long-term cultivation of mammalian cell types.ORR, CDER, FDA Mod-1, Room 2023, 8301 Muirkirk Road, Laurel MD 20708, USA     

Additional mapping of mouse chromosome 2 genes

The purpose of this work was to elucidate the genetic fine structure of the central portion of mouse chromosome (Chr) 2. Seven Chr 2 congenic mouse strains [B10.PA(L)-pa we un a ^t , B10.PA(L)-pa A ^w , B10.PA(L)-we un a ^t , B10.PA(J)-pa a, B10.FS-we A ^w , B10.C-we A ^w , and B10.YBR-a] were produced. Breeding studies were carried out using strains B10.PA(L)-pa we un a ^t and B10.LP-H-13 ^b to accurately determine the recombination frequencies between marker genes pa and we (1.9%±0.3), we and un (8.8%±0.5), and un and a ^t (4.5%±0.4) of strain B10.PA(L)-pa we un a ^t . These strains and other Chr 2 congenic strains were typed for immunologically defined loci using monoclonal antibody (mAb) C23 reactive with the gene product of B2m ^b T-lymphocyte clone C1 reactive with the gene product of H-3 ^a and H-3 ^c , and lymphocyte clone H1.8 reactive with the gene product of Hd-1 ^a . B2m and H-3 typing located a recombinational event separating [pa B2m H-3] from we (the order of bracketed genes is not known). Hd-1 typing indicated that Hd-1 maps distal to [H-42, H-44] and proximal to un. The gene order [pa, B2m, H-3], we, [H-42, H-45], Hd-1, un, H-13, a ^t , with H-44 mapping centromeric to Hd-1, is indicated by the data. Address correspondence and offprint requests to: R. J. Graff.     

Expression of the core antigen gene of hepatitis B virus (HBV) in Acetobacter methanolicus using broad-host-range vectors

Summary Using the broad-host-range promoter probe vector pRS201 for cloning of phage Acm1 promoters, we established a convenient vector system for expression of heterologous genes in different Gram-negative bacteria. The usefulness of this system was demonstrated by expression of the HBV core gene in Acetobacter methanolicus. Plasmids carrying the HBV core gene downstream of different Acm1-phage promoters were transferred to A. methanolicus, a new potential host for recombinant DNA expression. Using enzyme immunoassay and immunoblot techniques, the amount and composition of core antigen produced in A. methanolicus were compared with that derived from Escherichia coli. The expression of immunoreactive core antigen in A. methanolicus exceeds by sevenfold that in E. coli using an expression system with tandemly arranged promoters. Morphological observations by electron microscopy show that the HBV core gene products isolated from both hosts are assembled into regular spherical particles with a diameter of about 28 nm that are comparable to original viral nucleocapsids. Offprint requests to: R. Schröder     

Two novel protein-tyrosine kinases, each with a second phosphotransferase-related catalytic domain, define a new class of protein kinase.

The protein-tyrosine kinases (PTKs) are a burgeoning family of proteins, each of which bears a conserved domain of 250 to 300 amino acids capable of phosphorylating substrate proteins on tyrosine residues. We recently exploited the existence of two highly conserved sequence elements within the catalytic domain to generate PTK-specific degenerate oligonucleotide primers (A. F. Wilks, Proc. Natl. Acad. Sci. USA 86:1603-1607, 1989). By application of the polymerase chain reaction, portions of the catalytic domains of several novel PTKs were amplified. We describe here the primary sequence of one of these new PTKs, JAK1 (from Janus kinase), a member of a new class of PTK characterized by the presence of a second phosphotransferase-related domain immediately N terminal to the PTK domain. The second phosphotransferase domain bears all the hallmarks of a protein kinase, although its structure differs significantly from that of the PTK and threonine/serine kinase family members. A second member of this family (JAK2) has been partially characterized and exhibits a similar array of kinase-related domains. JAK1 is a large, widely expressed membrane-associated phosphoprotein of approximately 130,000 Da. The PTK activity of JAK1 has been located in the C-terminal PTK-like domain. The role of the second kinaselike domain is unknown.     

Seasonal cycles of reserves in relation to reproduction inSebastes

Synopsis Seasonal cycles of reserve deposition and utilization in many fishes, amphibians and reptiles alleviate temporal mismatches of energy supply and demand. Utilization of reserves can be related to maintenance during periods of reduced food supply, to reproduction, particularly during periods of poor food availability, and to migration. Published data on the seasonal cycles of reserves and reproduction inSebastes suggest that reserves are important for maintenance during wintertime periods of low food availability. Unlike many other ectothermic vertebrates, some species ofSebastes deposit fat reserves at the same time as gametogenesis, a pattern consistent with the longevity and iteroparity evident in the genus. Other species ofSebastes have similar seasonal timing of fat cycles, but since reproduction takes place later in the year, the decline in reserves during winter coincides with the main period of reproductive activity. The significance of this is not clear. Interspecific differences in amounts of reserves may be related to geographical differences in the seasonality or abundance of food. Intraspecific variation in reserves, marked most strongly by allometry of reserves with regard to fish legth, bears further study, since it may link the proces of sexual maturation and the responses of repeat spawners to variability in food supply and other environmental factors.     

Relationship between sensitivity to 4'-(9-acridinylamino)methanesulfon-m-anisidide and DNA topoisomerase II in a cold-sensitive cell-cycle mutant of a murine mastocytoma cell line

The cold-sensitive (proliferating at 39.5 degrees C, reversibly arrested in GI-phase at 33 degrees C) cell-cycle mutant 21-Fb of the murine mastocytoma cell line P815 was used to study the effect of amsacrine on non-cycling cells. The sensitivity of arrested 21-Fb cells decreased less than 2-fold in cell survival experiments when compared to proliferating cells. In contrast, DNA breakage and stimulation of protein-DNA complex formation in intact or lysed cells was reduced approx. 10-fold in arrested cells and DNA topoisomerase II activity in arrested cells was only 5% of the activity in proliferating cells. Thus, there was no correlation between cell survival and DNA damage or DNA topoisomerase II activity in drug-treated cells.