Genetic interaction between Non-MHC T- and B-cell alloantigens in response to rous sarcomas in chickens

Chickens of Regional Poultry Research Laboratory (RPRL) inbred line 6₃ regress sarcomas induced by Bryan high-titer Rous sarcoma virus to a greater extent than chickens of line RPRL 100, although these lines are identical for the major histocompatibility B complex. They differ, however, at three independent autosomal loci: Ly-4 and Th-1 determine the surface alloantigens of partly overlapping subsets of T lymphocytes, and Bu-1 determines a surface alloantigen of B lymphocytes. The association of genotypes at these loci with quantitative variation in their ability to regress Rous sarcomas was tested in segregating F₄ generation progeny derived from crosses of lines 100 and 6₃. The Ly-4 and Bu-1 genotypes showed association with Rous sarcoma regression, but the Th-1 genotype did not. Chickens of the Ly-4 ^a/Ly-4 ^a, Bu-1 ^b/Bu-1 ^b and Ly-4 ^b/Ly-4 ^b, Bu-1 ^a/Bu-1 ^a genotypes had a significantly higher regressor ability than the other two double homozygous genotypes. These results indicate that higher regression is associated with (1) interaction between the Ly-4 and Bu-1 loci, and (2) complementation between either the line 6 Ly-4 ^a allele and the line 100 Bu-1 ^b allele, or the line 100 Ly-4 ^b allele and the line 6 Bu-1 ^a allele.     

Direct acid-catalysed transmethylation of lactobacillic acid in lactic acid bacteria

Summary Cellular fatty acids inLactobacillus büchneri were transmethylated with H₂SO₄ catalyst in methanol at elevated temperature. By optimising the reaction time and the amounts of catalyst and methanol used at a fixed temperature it was possible to maximise the lactobacillic acid yield. The yield of lactobacillic acid with this method was better than with the traditional method using base-catalysed saponification followed by HCL-catalysed methylation.     

Ontogeny,environment, and shape of a marine snail Thais lamellosa Gmelin

Shell shape, as expressed in terms of log weight/log length, (relative weight), changes progressively as Thais lamellosa Gmelin grows. Relative weight decreases at all sites, but the decrease is relatively rapid at localities with low food supply and correspondingly low growth rates. Snails at these sites are ‘slender’ relative to those at sites with greater barnacle populations. The sitespecific shapes are phenotypic, since snails with fat and with slender parents all became slender in the laboratory where food was readily available and growth rates were higher than those observed at most field localities. Since these snails did not become ‘fat’, food abundance is not the immediately causal, environmental factor promoting a slow change in relative weight. Two other species of Thais live in the same places and undergo similar changes in relative weight.     

Low-density lipoprotein preparation by combined diafiltration and ultracentrifugation

A method for isolating low-density lipoprotein by combining diafiltration and ultracentrifugation is described. Diafiltration separates plasma components by use of an ultrafiltration membrane that excludes particles of molecular weight greater than 300,000. The retentate is concentrated three- to fourfold by ultrafiltration, allowing large-scale preparation of low-density lipoprotein. Low-density lipoprotein prepared in this manner is similar in physical, chemical, and biologic properties to low-density lipoprotein isolated by sequential density ultracentrifugation alone. When low-density lipoprotein, prepared by either method, was added to human umbilical vein endothelial cell cultures, no cytotoxicity was observed. The techniques described reduce the demand on multiple rotors and ultracentrifuges for large-scale preparation of low-density lipoprotein suitable and often needed for tissue culture studies.     

Restriction fragment length polymorphism at the HLA-C locus

We have used the HLA-C-specific DNA probe pC250 to investigate restriction fragment length polymorphism (RFLP) at the HLA-C locus. Genomic Southern blot hybridization included DNA prepared from a panel of homozygous typing cells representing serological specificities Cw1 to Cw8 and also from samples representing Cw blanks. Although many restriction nucleases failed to reveal any polymorphism, RFLPs were evident with Taq I, Pvu II, Bst XI, Nde 1, and Nci I in addition to the previously reported Eco RI. In the case of Bst XI, a unique RFLP defined a subset of serologically defined Cw blanks. Comparison of RFLP sizes with restriction fragment lengths obtained from the known HLA-Cw3 gene sequence permitted the localization of intragenic C locus RFLLs and the identification of a variable Taq I site in the second intron, a variable Nci I site near the end of the fourth exon, and a variable Pvu lI site in the fifth intron.     

Characterization of a class of small auxin-inducible soybean polyadenylated RNAs

Four new auxin-responsive RNAs from soybean (Glycine max (L.) Merr., var. Wayne) are described. The RNAs were identified by hybridization to three cDNA probes obtained from a library enriched for sequences which increase in abundance within 60 min after 2,4-D (2,4-dichlorophenoxyacetic acid) treatment. These RNAs appear to define a new class of small (i.e. approximately 550 nucleotides) RNAs that respond extremely rapidly to application of exogenous auxin. In excised elongating hypocotyl sections, an increase in the abundance of these RNAs can be detected 2 to 5 min after treatment with 50 M 2,4-D. This response is half maximal after 10 min and reaches steady state in 60 min. RNA blot analysis shows that these RNAs are expressed differentially in various parts of the seedling. The degree of inducibility by auxin is also organ-specific, with the elongating hypocotyl being the most responsive of the organs tested. The RNAs display identical response specificities with one exception. Accumulation of one RNA, designated 10A, is completely abolished by simultaneous addition of cycloheximide and 2,4-D. This RNA also displays a different 2,4-D dose response than other RNAs examined. These results suggest that more than one mechanism is involved in rapid modulation of gene expression by auxin.     

Life history adaptations of Gasterosteus aculeatus in a Mediterranean wetland

Synopsis The life cycle of leiurus-type Gasterosteus aculeatus occurring in a Mediterranean coastal wetland is described. Fish have a low number of lateral plates, short spines and marked sexual dimorphism in size. The life cycle is strictly annual, adults dying shortly after breeding. Adult fish migrate into seasonally-flooded freshwater marshes to breed, and the young migrate back to brackish water to pass the summer and autumn. Breeding occurs in March at water temperatures of about 10°C, the season lasting about 50 days. Growth of fish occurs throughout the year, but differs from year to year, resulting in variable adult size. Maximum gonadal investment of male fish is in autumn, whereas that of females is in spring. Gonadal investment of female fish, as measured by gonado-somatic index and fecundity, is higher than in other studied leiurus populations, but the number of clutches produced in a season is probably low. These differences in life history from other studied populations of sticklebacks are seen as adaptations to a mediterranean-type climate (high summer temperatures, seasonality of water bodies) and to heavy predation by fish-eating birds.     

Limiting factors for seed production in Cynoglossum officinale

Summary Over three years of study, small plants of Cynoglossum officinale consistently produced more flowers per unit of dry weight than large plants. In contrast to earlier results, weight of all seeds tended to increase more than proportional to size. As a result a positive correlation existed between seed set per flower and plant size. The correlation between the mean number of pollinator visits per flower and size was positive but not significant. In a field experiment we found that resources rather than pollen were limiting seed set. Thus, it is unlikely that enhanced pollination of the largest plants causes the size-dependency of seed set per flower. Alternative hypotheses are discussed briefly.Publication of the Meijendel Comité, New Series No. 96