Mutations Affecting Acetylcholine Levels in the Nematode Caenorhabditis elegans

Gene cha-1.unc-17 of the nematode Caenorhabditis elegans is a complex gene, consisting of at least two complementation groups. One part (cha-1 region) of the gene encodes the enzyme choline acetyltransferase (ChAT), but the function of the other part (unc-17 region) is still unclear. We measured the ChAT activity and ACh levels of the cha-1 and unc-17 complex gene mutants. We show here that alterations in ACh levels, rather than the ChAT activity, reflect abnormal phenotypes accompanying cha-1.unc-17 mutations, that is, the decreased ACh levels in cha-1 mutations and abnormal accumulation in unc-17 mutations. Our results suggest that the unc-17 region may encode functions necessary for storage and/or release of ACh at the presynaptic level.     

Revision of the plant geographical territories of Israel and Sinai

The phytogeographical territories of Israel and Sinai are revised using a large mass of species distribution data. With the help of chorotype frequencies for 25 km² individual squares in Israel, territories were defined on the basis of the first two most frequent chorotypes. The similarity of boundaries in the resulting phytogeographical map with a physiognomic map suggests that the latter may be used in preliminary stages of the preparation of plant geographical maps.     

Electrostatic calculations and model-building suggest that DNA bound to CAP is sharply bent

Two observations suggest that DNA, upon binding to E. coli catabolite gene activator protein (CAP), is sharply bent by a total angle of at least 100-150 degrees: (1) The electrostatic potential field of CAP shows regions of positive potential that form a ramp on 3 sides of the protein. (2) The DNA binding site size as determined by DNA ethylation interference with binding, (Majors: "Control of the E. coli Lac Operon at the Molecular Level." Ph.D. Thesis, Harvard University, Cambridge, 1977) and by relative affinities of DNA fragments of various lengths (Liu-Johnson et al.: Cell 47:995-1005, 1986) requires severe bending of the DNA to maintain its favorable electrostatic contact with the protein.     

The effect of Brugia pahangi infection on survival of susceptible and refractory species of the Aedes scutellaris complex

Life table statistics were used to examine the survival functions of filarial susceptible and refractory species of the Aedes scutellaris (Walker) group of mosquitoes, following infection with high and moderate doses of Brugia pahangi (Buckley & Edeson). Survivorship curves and hazard function curves were generated, and the median survival times and the proportions of mosquitoes surviving beyond the extrinsic incubation period of the parasite were determined. In the susceptible populations of Aedes polynesiensis Marks, Ae. pseudoscutellaris (Theobald) and Ae.tabu Ramalingam & Belkin a dose-response relationship was detected between parasite load and mortality. This relationship was characterized by a significant reduction in the proportions of infected female mosquitoes surviving at days 1 and 9 postinfection, reduction in the median survival times and an increase in the hazard rates as the infectious dose increased. The survival of the refractory species, Ae.alcasidi Huang and Ae.katherinensis Woodhill was not significantly affected by the infection. A positive correlation between microfilaraemia in the vertebrate host and parasite load in the susceptible mosquito populations was also observed. Regression analysis of the number of parasites recovered from susceptible mosquitoes at the time of death showed that mosquitoes at highest risk of dying harboured from 11.6 to 19.4 infective larvae when fed on a gerbil with sixty-five microfilariae per 20 microliters blood; this resulted in 34.4-40.2% mortality by day 9 postinfection. A mean number of 32.6-46.9 infective larvae was observed when these populations were exposed to a gerbil with a microfilaraemia of 150 mf/20 microliters and resulted in 72.8% to 80% mortality in these populations. Viable infective larvae were recovered from infected mosquitoes up to 50 days postinfection.     

Major histocompatibility (B) complex and sex effects on the phytohaemagglutinin wattle response

The influence of the major histocompatibility (B) complex and sex on the phytohaemagglutinin (PHA) wattle response was studied in 136 segregants (B2/B2, B2/B5 and B5/B5) of a fourth generation cross between inbred lines 6(1) and 15(1). At 6 weeks of age, chickens were injected with 100 micrograms purified PHA-P. Wattle thickness measurements were taken 4, 24, 48, 72 and 96 h after injection. Analysis of variance showed that 4 h after injection, males had a significantly higher response than females but the sex-genotype interaction was also significant. Females had higher responses than males 24 and 48 h after injection as a consequence of more rapid development and earlier resolution of the reaction in males. B2/B2 chickens had significantly lower responses than B5/B5 chickens 72 and 96 h after injection, signifying a faster late resolution phase in the B2/B2 genotype. The developmental and early resolution phases of the PHA wattle response were influenced by sex while the late resolution phase was influenced by B genotype.     

Filipin-sterol complexes in golden hamster sperm membranes with special reference to epididymal maturation

Summary The distribution of membrane filipin-sterol complexes (FSCs) was qualitatively surveyed on freeze-fracture replicas of spermatozoa from the male reproductive tract and ejaculates of golden hamster. In the head, the acrosomal plasma membrane showed the strongest filipin labeling on the principal segment, but it was absent in the quilt-like pattern areas. These latter were observed in both caput and corpus epididymal spermatozoa, but were absent in mature spermatozoa. The postacrosomal plasma membrane had few FSCs and both the outer and inner acrosomal membranes were always negative to filipin. The nuclear membrane of the principal segment was constantly filipinpositive. The nuclear membrane of the postacrosomal region had more FSCs than that of the principal segment, particularly in mature spermatozoa. Many linear, rod-like FSCs were observed on the postacrosomal nuclear membrane of mature spermatozoa, especially in the uterine spermatozoan samples. In the neck, the plasma membrane had only a few FSCs. The redundant nuclear membrane was slightly filipin-positive, while the membrane scroll of mature spermatozoa was heavily labeled. In the tail, the plasma membrane of both the middle and principal piece was moderately labeled.     

Insect-induced chemical changes in young lodgepole pine (Pinus contorta): the effect of previous defoliation on oviposition, growth and survival of the pine beauty moth, Panolis flammea

ABSTRACT. 1. Significantly more eggs were laid by adult female pine beauty moths ( Panolis flammea (D&S)) on previously undefoliated lodgepole pine ( Pinus contorta Douglas) saplings than on those which had been partially defoliated the year before.
2. The larval weights, mean relative growth rates and survival rates of P.flammea were lower on defoliated trees than on undefoliated trees.
3. Marked and significant differences between the monoterpene profiles of the shoot cortical oleoresin of defoliated and undefoliated trees were linked to oviposition preferences in P.flammea.
4. Differences occurred between the levels of soluble tannins in previously defoliated and undefoliated trees.
5. The results are discussed in relation to earlier work on insect-induced changes in plants, and the significance of inter-provenance differences in lodgepole pine response is assessed.     

Search for Drosophila genes encoding a conserved domain present in the achaete-scute complex and myc proteins

Summary Several genes of the achaete-scute complex (ASC) of Drosophila melanogaster encode a 60 amino acids long conserved domain which shares a significant homology with a region of the vertebrate myc proteins. Based on these results, the existence of a family of Drosophila genes that would share both this conserved domain and the neurogenic function of the AS-C has been postulated. To test this proposal, we have searched a D. melanogaster genomic library with a probe that encodes the conserved domain. Only under very low stringency hybridization conditions, clones not belonging to the AS-C cross-hybridized with the probe. Those that gave the strongest signals were characterized. Sequencing of the cross-hybridizing regions showed that they had no significant homology with the conserved domain, the sequence similarity extending at the most for 37 nucleotides. Although our results do not conclusively disprove the existence of a family of AS-C-like genes, they indicate that the conservation of the domain would be lower than that found for shared motifs in other families of Drosophila developmental genes.     

Purification and partial characterisation of two abscisic-acid-responsive proteins induced in cultured embryos ofPisum sativum L.

When pea (Pisum sativum L.) embryos were cultured on low osmotica, with or without added abscisic acid (ABA), there was very little change in the total mRNA translation products resolved by one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The only marked alteration was an increase in production of two low-molecular-weight proteins. The purification and partial characterisation of these two ABA-responsive seed proteins (ABR17 and ABR18) is described. Both proteins were purified to homoeneity, as judged by SDS-PAGE, from embryos cultured in the presence of ABA. Antisera were raised against both proteins. Each serum cross-reacted with the other protein, indicating that the proteins are closely related. Their apparent molecular masses (M_rs) were estimated to be 17200 (ABR17) and 18100 (ABR18) by SDS-PAGE, and 26000 by gel filtration. Both proteins were heterogeneous on isoelectric focusing. Neither protein was detected (by immunoblotting or immunoprecipitation of cell-free translation products) in embryos grown in vivo at early to mid-development stages but both were present in embryos late in development. These proteins appear to be produced late in seed development but are capable of being induced early in development by culturing embryos in vitro and are markedly enhanced by ABA.     

Development of the preprophase band from random cytoplasmic microtubules in guard mother cells of Allium cepa L.

The organization of microtubule (MT) arrays in the guard mother cells (GMCs) of A. cepa was examined, focussing on the stage at which a longitudinal preprophase band (PPB) is established perpendicular to all other division planes in the epidermis. In the majority of young GMCs, including those seen just after asymmetric division, MTs are distributed randomly throughout the cortex and inner regions of the cytoplasm. Few MTs are associated with the nuclear surface. As the GMCs continue to develop, MTs cluster around the nucleus and a PPB appears as a wide longitudinal band. Microtubules also become prominent between the nucleus and the periclinal and transverse walls, while they decrease in number along the radial longitudinal walls. The PPB progressively narrows by early prophase, and a transversely oriented spindle gradually ensheaths the nucleus. These observations indicate that the initial, broad PPB is organized by a rearrangement of the random cytoplasmic array of MTs. Additional reorganization is responsible for MTs linking the nucleus and the cortex in the future plane of the cell plate, and for narrowing of the PPB.Abbreviations GMC guard mother cell - MT microtubule - PPB preprophase band