Life history and habitat requirements of the Oregon forestsnail, Allogona townsendiana (Mollusca, Gastropoda, Pulmonata, Polygyridae), in a British Columbia population

Abstract. Population size, reproductive timing and habitats, seasonal behaviors, and juvenile activity were assessed in a British Columbia population of the endangered Oregon forestsnail, Allogona townsendiana , over a period of 4 years. Adult snail population size ranged from seven to 47 snails in four × 24-m² sampling sites. The mating period peaked in March and April; adults aggregated in clusters of eight to 14 snails before mating. Pairs of snails were observed to mate for 225 min or more in close proximity to coarse woody debris and stinging nettle, Urtica dioica. Nesting peaked in April–May and resulted in a mean clutch size of 34 eggs (SD=9). Hatching for two nests occurred at 63 and 64 d after oviposition. Within hours of hatching, juveniles began dispersing from the nest site; by 1 month most had disappeared. Snails tracked with harmonic radar became less active or aestivated from late July to early September and hibernated from early November to mid-March within leaf litter and soil. Preliminary measurements of growth rate indicate this species takes a minimum of 2 years to reach adulthood and has a typical life span of at least 5 years.     

Translation of chloroplast psbD mRNA in Chlamydomonas is controlled by a secondary RNA structure blocking the AUG start codon

Translation initiation represents a key step during regulation of gene expression in chloroplasts. Here, we report on the identification and characterization of three suppressor point mutations which overcome a translational defect caused by the deletion of a U-rich element in the 5′-untranslated region (5′-UTR) of the psbD mRNA in the green alga Chlamydomonas reinhardtii. All three suppressors affect a secondary RNA structure encompassing the psbD AUG initiation codon within a double-stranded region as judged by the analysis of site-directed chloroplast mutants as well as in vitro RNA mapping experiments using RNase H. In conclusion, the data suggest that these new element serves as a negative regulator which mediates a rapid shut-down of D2 synthesis.     

The quaternary structure of the sheaths of defective phages similar to PBS X.

The contractile sheaths of five defective, PBS X-like bacteriophages from Bacillus subtilis and B. licheniformis were investigated by electron microscopy, dodecylsulphate gel electrophoresis and immunodiffusion. Electron microscope images of the extended and contracted sheaths were of similar appearance, although their lengths were different. The surface lattices of both the extended and the contracted sheaths were determined by optical diffraction. This showed that the quaternary structure of the sheaths of all five defective phages originated from identical surface lattices, which could be approximately expressed by the selection rules L = -2n' + 3m and L = 9N' + 17M for the extended and contracted sheaths respectively, in which 6n' = n with n = 0 or an integer multiple of 6. These results indicated that the packing of the protein subunits in these sheaths differed from those of other bacteriophages, for example T4 and millimicron [Amos and Klug, J. Mol. Biol. 99, 51--73 (1975); Admiraal and Mellema, J. Ultrastruct. Res. 56, 48--64 (1976)]. The molecular weight of the main sheath protein of the defective phages, as determined by dodecylsulphate gel electrophoresis, was approximately 50000. This value differed from that for T4, but was similar to that of millimicron [Admiraal and Mellema, J. Ultrastruct. Res. 56, 48--64 (1976); King and Laemmli, J. Mol. Biol, 75, 315--337 (1973)]. The results of immunodiffusion experiments, however, pointed to a chemical difference between the sheath proteins of the defective phages and millimicron, in addition to T4.     

Gender identity development in adolescence

This article is part of a Special Issue "Puberty and Adolescence".This article aims to provide an outline of what is currently known on trajectories, and contributing factors to gender identity development in adolescence. We give a historical overview of the concept of gender identity, and describe general identity development in adolescence, gender identity development in the general population and in gender variant youth. Possible psychosocial (such as child and parental characteristics) and biological factors (such as the effects of prenatal exposure to gonadal hormones and the role of genetics) contributing to a gender variant identity are discussed.     

Enzymatic preparation of multimilligram amounts of pure single-stranded DNA samples for material and analytical sciences

We present a method for high-yield production of multimilligram amounts of pure single-stranded DNA employing rolling circle amplification (RCA) and processing by restriction enzymes. Pure and homogeneous samples are produced with minimal handling time, reagents, and waste products. The RCA method is more than twice as efficient in dNTP incorporation than conventional polymerase chain reaction in producing end product. The validity and utility of the method are demonstrated in the production of a uniformly ¹³C/¹⁵N-labeled 38-nt cocaine aptamer DNA used in nanosensing devices.     

Oral or nasal antigen induces regulatory T cells that suppress arthritis and proliferation of arthritogenic T cells in joint draining lymph nodes

The propagation of mucosal tolerance as a therapeutic approach in autoimmune diseases remains a difficult goal to achieve, and therefore further mechanistic studies are necessary to develop potential clinical protocols to induce mucosal regulatory T cells (Tr cells). In this study we addressed whether oral or nasal proteoglycan induced functional Tr cells in the cartilage proteoglycan-induced chronic arthritis model. Both nasal and oral application of human proteoglycan before induction of disease suppressed arthritis severity and incidence. Tolerized mice showed enhanced numbers of IL-10 producing CD4(+) cells in the paw-draining lymph nodes. Furthermore, CD4(+) spleen cells displayed enhanced expression of molecules associated with Tr cells, such as IL-10, Foxp3, and TGF-beta. Transfer of CD4(+) spleen cells from mucosally tolerized donors into proteoglycan-immunized mice abolished arthritis and reduced humoral responses, indicative of Tr cells with the capacity to inhibit already induced immune responses. Tr cells were activated upon transfer, because enhanced proliferation was observed in the joint draining lymph nodes compared with activated T cells from nontolerized donors. Upon cotransfer with naive proteoglycan-specific T cells, mucosally induced Tr cells inhibited proliferation of these arthritogenic T cells in vivo. Herein we show that both oral and nasal Ag application induced Tr cells, which had a direct inhibitory effect on already established pathogenic B and T cell responses.     

Construction of a genomic library of the food spoilage yeast Zygosaccharomyces bailii and isolation of the beta-isopropylmalate dehydrogenase gene (ZbLEU2)

A genomic library of the yeast Zygosaccharomyces bailii ISA 1307 was constructed in pRS316, a shuttle vector for Saccharomyces cerevisiae and Escherichia coli. The library has an average insert size of 6 kb and covers the genome more than 20 times assuming a genome size similar to that of S. cerevisiae. This new tool has been successfully used, by us and others, to isolate Z. bailii genes. One example is the beta-isopropylmalate dehydrogenase gene (ZbLEU2) of Z. bailii, which was cloned by complementation of a leu2 mutation in S. cerevisiae. An open reading frame encoding a protein with a molecular mass of 38.7 kDa was found. The nucleotide sequence of ZbLEU2 and the deduced amino acid sequence showed a significant degree of identity to those of beta-isopropylmalate dehydrogenases from several other yeast species. The sequence of ZbLEU2 has been deposited in the EMBL data library under accession number AJ292544.