The repertoire of human germline VH sequences reveals about fifty groups of VH segments with different hypervariable loops.

We have used the polymerase chain reaction and VH family-based primers to clone and sequence 74 human germline VH segments from a single individual and built a directory to include all known germline sequences. The directory contains 122 VH segments with different nucleotide sequences, 83 of which have open reading frames. The directory indicates that the structural diversity of the germline repertoire for antigen binding is fixed by about 50 groups of VH segments: each group encodes identical hypervariable loops. The directory should help in mapping the VH locus, in estimating somatic mutation and VH segment usage and in designing and constructing synthetic antibody libraries.     

Snow-patch foraging by pink-footed geese Anser brachyrhynchus in south Iceland

The pre-nesting feeding behaviour of pink-footed geese was studied in hayfields in southern Iceland during the late spring of 1989. Persistent snow-patches protected underlying grass from the effects of severe night-time frost. Areas within 1 m of snow-patches had significantly greater amounts of green material than those further away; green material contained more than double the protein of brown, dead material, which predominated in open fields. Geese spent nearly 60 times more time feeding within 1 m of snow patches than expected by chance, and 20 times more time within 2–5 m. Their feeding rates here were faster and their step rate slower than further away. In this way, the geese selected the prime forage as soon as it became available.     

A potent and selective photoaffinity probe for the anti-estrogen binding site of rat liver

The anti-estrogen binding site (ABS) is an apparently ubiquitous component of cells that has been shown to be intimately linked with the antiproliferative effects of certain antiestrogenic compounds, like tamoxifen, which is currently used for the treatment of breast cancer. However, the identification and in vitro study of this novel protein has been hampered to date by a lack of convenient probes that will efficiently label the molecule in nonpurified preparations. Thus, using a selective ABS ligand (4-benzylphenoxy-N-ethylmorpholine, MBPE) as starting material, we synthesized a photosensitive azido derivative, [(2-azido-4-benzyl)phenoxy]N-ethylmorpholine (azido-MBPE) that can be prepared in a tritiated form. Azido-MBPE has a high affinity for ABS (Kd = 3 nM), identical to that of tamoxifen, and covalently labels 5 and 12% of membrane-bound and detergent-solubilized ABS, respectively. Its incorporation is selectively and competitively inhibited by other ABS ligands (tamoxifen greater than nitromifen greater than hydroxytamoxifen). [3H]Azido-MBPE potently photolabels either membrane-bound or detergent-solubilized ABS as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under denaturing conditions revealing specific photoincorporation in a protein band of Mr = 40,000. This molecular weight is approximately two times lower than what we observed previously for ABS preparations studied under nondenaturing conditions and postlabeled with [3H]tamoxifen (Mr = 80,000-110,000). In chromatofocusing experiments with photolabeled ABS, a single specifically labeled protein fraction migrating with a pI of 6.4 was found to exhibit a Mr of 40,000 when subsequently electrophoresed on sodium dodecyl sulfate-polyacrylamide gels. These results indicate that [3H]azido-MBPE is a specific high affinity probe of ABS that will prove useful in the ultimate identification of this protein.     

Evidence that calmodulin may be involved in phytohaemagglutinin-stimulated lymphocyte division

Phytohaemagglutinin-stimulated and non-stimulated incorporation of [³H]thymidine into human peripheral blood lymphocytes is inhibited by the calcium antagonist PY 108–068 and by the calmodulin antagonists trifluo-perazine andN-(6-aminohexyl)-5-chloro-l-naphthalene sulphonamide (W7). It is argued that calmodulin may be involved in both non-stimulated [³H]thymidine uptake in lymphocytes and also in the lymphocyte response to phytohaemagglutinin.     

Neural and hormonal stimulation of DNA and protein synthesis in cultured regeneration blastemata in the newt Notophthalmus viridescens

Distal portions of cone-stage newt forelimb blastemata were cultured transfilter to spinal ganglia for 36 or 72 hr. Addition of insulin to the medium consistently resulted in a significant increase (250% in ganglionated and 238% in nonganglionated blastemata) in the incorporation of [³H]thymidine into DNA, as compared to nontreated controls. When blastemata were cultured without ganglia for 36 or 72 hr, DNA synthesis decreased to 73 and 71%, respectively, of that achieved by ganglionated explants. When insulin was excluded from the medium, DNA synthesis decreased to 40% of insulin-treated explants, and, in the absence of both nerves and insulin, it declined to 31% of insulin-treated, innervated explants. The presence of insulin in the medium also resulted in an augmentation of (¹⁴C)-labeled amino acid incorporation into proteins; the average increase was 168%, as compared to untreated controls. l-thyroxine, growth hormone and hydrocortisone in combination with insulin, did not enhance the effects on DNA or protein synthesis of insulin alone. Also, exogenous cyclic nucleotides (cAMP, cGMP) and alterations of their endogenous levels with acetylcholine, sodium azide, theophylline or prostaglandins failed to elicit significant changes in DNA or protein synthesis. The existence of a synergistic action on DNA synthesis between nerves and insulin is suggested.     

Aerial dispersal of biological material from Australia to New Zealand

New Zealand lies 2000 km across the Tasman Sea, southeast of Australia, in the path of prevailing westerly winds and thus is well sited for studies of long distance dispersal. The aerial transfer of biological material across the Tasman Sea from Australia to New Zealand is not well documented and evidence for this is reviewed. Plant Pathogens: Regular surveys have identified the races of wheat stem rust present in both countries. In general the identification of a new race in Australia was quickly followed by its appearance in New Zealand. SimilarlyAntirrhinum rust and poplar leaf rusts were detected in New Zealand soon after their first appearance in Australia. Insects: Coccids, the grain aphid, and blue moon and other butterflies and moths appear to have been carried across the Tasman during appropriate meteorological conditions. Seeds and Pollen: There is evidence for a west to east movement of seeds, spores and pollen. The affinities of the orchid and fern floras between the two countries provides circumstantial evidence and it is generally accepted thatCasuarina pollen found in peat and surface samples from various parts of New Zealand has its source in eastern Australia.     

Mapping of the mitochondrial 16S ribosomal RNA gene and its expression in the cytoplasmic petite mutants ofSaccharomyces cerevisiae

The 16S ribosomal RNA gene of yeast mitochondria was titrated in various cytoplasmic petite mutants by DNA-RNA hybridization. The gene was located close to the prolyl transfer RNA gene. The properties of the rho^? strains suggest that the gene order would be: - P_I - 16S - prolyl tRNA - valyl tRNA - (tRNAs) - R_I - R_III -; the 23S ribosomal gene is far from the 16S one. Several petite mutants were found which have retained, in addition to many transfer RNA genes, both of the 23S and 16S ribosomal RNA genes. The two genes seem to be transcribed in these mutants.     

Cyanide-resistant Respiration of Sweet Potato Mitochondria

The oxidation of malate and succinate by sweet potato mitochondria (Ipomoea batatas [L.] Lam.) was blocked only partly by inhibitors of complexes III (2-heptyl-4-hydroxyquinoline-N-oxide) and IV (cyanide and azide). The respiration insensitive to inhibitors of complexes III and IV was inhibited by salicylhydroxamic acid. Essentially complete inhibition was obtained with inhibitors of complex I (rotenone, amytal, and thenoyltrifluoroacetone) and complex II (thenoyltrifluoroacetone). The observations indicated that electrons were transferred to the cyanide-resistant pathway from ubiquinone or from nonheme iron (iron-sulfur) proteins of complexes I and II before reaching the b cytochromes. In contrast, the oxidation of exogenous NADH did not involve the alternate pathway, as indicated by complete inhibition by inhibitors of complexes III and IV and the absence of an effect of inhibitors of complexes I and II. Hence, electrons from exogenous NADH appear to pass directly to complex III in sweet potato mitochondria.