Effect of sulphasalazine on the human intestinal flora

Sulphasalazine is commonly used to treat patients with ulcerative colitis but the mode of action is still unexplained. To investigate a possible antibacterial effect of sulphasalazine, the faecal flora composition was studied in patients with ulcerative colitis and in mice harbouring a human intestinal flora. Patients on sulphasalazine were found to have an intestinal flora that was completely resistant to sulphapyri-dine. Oral administration of sulphasalazine did not influence the composition of the human flora in mice.     

SUT2, a putative sucrose sensor in sieve elements

In leaves, sucrose uptake kinetics involve high- and low-affinity components. A family of low- and high-affinity sucrose transporters (SUT) was identified. SUT1 serves as a high-affinity transporter essential for phloem loading and long-distance transport in solanaceous species. SUT4 is a low-affinity transporter with an expression pattern overlapping that of SUT1. Both SUT1 and SUT4 localize to enucleate sieve elements of tomato. New sucrose transporter-like proteins, named SUT2, from tomato and Arabidopsis contain extended cytoplasmic domains, thus structurally resembling the yeast sugar sensors SNF3 and RGT2. Features common to these sensors are low codon bias, environment of the start codon, low expression, and lack of detectable transport activity. In contrast to LeSUT1, which is induced during the sink-to-source transition of leaves, SUT2 is more highly expressed in sink than in source leaves and is inducible by sucrose. LeSUT2 protein colocalizes with the low- and high-affinity sucrose transporters in sieve elements of tomato petioles, indicating that multiple SUT mRNAs or proteins travel from companion cells to enucleate sieve elements. The SUT2 gene maps on chromosome V of potato and is linked to a major quantitative trait locus for tuber starch content and yield. Thus, the putative sugar sensor identified colocalizes with two other sucrose transporters, differs from them in kinetic properties, and potentially regulates the relative activity of low- and high-affinity sucrose transport into sieve elements.     

An improved survey method for monitoring population trends of Golden‐winged Warblers and other patchily distributed birds

Conventional surveys designed to monitor common and widespread species may fail to adequately track population changes of rare or patchily distributed species that are often of high conservation concern. We evaluated the performance of a new monitoring approach that employs both a spatially balanced sampling design and a targeted survey protocol designed to estimate population trends of one such patchily distributed species, the Golden‐winged Warbler (Vermivora chrysoptera), in the Appalachian Mountains Bird Conservation Region (BCR 28), USA. Our spatially balanced survey consisted of 105 sample quads (one‐quarter Delorme Atlas pages) across the current range of Golden‐winged Warblers within BCR 28, each with five sample points located in early successional habitat. From 2009 to 2013, collaborators visited each sample point once per year during the peak breeding season and conducted a 17‐min survey consisting of passive observation and playback of conspecific songs and mobbing vocalizations. We used multi‐season, single‐species occupancy models to estimate probability of quad occupancy, detection probability, and occupancy dynamics for Golden‐winged Warblers and closely related Blue‐winged Warblers (Vermivora cyanoptera). Our survey protocol resulted in high estimates of detection probability for Golden‐winged (92%) and Blue‐winged (79%) warblers, with 47% and 56% of quads estimated to be initially occupied, respectively. Derived population trend estimates (λ) indicated an average decline in population of 6% for Golden‐winged Warblers and 7% for Blue‐winged Warblers, resulting in estimated 21% and 22% declines, respectively, in quad occupancy after 5 yr. Our results demonstrate that coupling a spatially balanced survey design in appropriate habitat with a playback protocol to increase detection rates is a viable strategy for tracking populations of Golden‐winged Warblers in the Appalachian Mountains BCR. Similar survey methods should be considered for other rare, declining, or patchily distributed bird species that require targeted monitoring.     

Leishmania braziliensis:Characterisation of a Complex Specific Subtelomeric Repeat Sequence and Its Use in the Detection of Parasites

Fu, G., Perona-Wright, G., and Barker, D. C. 1998.Leishmania braziliensis: Characterisation of a complex specific subtelomeric repeat sequence and its use in the detection of parasites.Experimental Parasitology90, 236–243. A 1.6-kb tandem repeat sequence had previously been identified in the subtelomeric region of mini- and megabase chromosomes fromLeishmania braziliensis.Southern hybridisation was used to demonstrate that the repeat is complex specific. The sequence was characterised in strains representing four species of theL. braziliensiscomplex. This data allowed an assessment of the evolutionary relationship of the four species. PCR primers targeted to the repeat amplify only DNA from species of theL. braziliensiscomplex. Titration assays indicate that a minimum of 50 fg of parasite DNA can be detected by PCR alone. Southern hybridisation increases the limit of detection to 5 fg. Interspecies variation in the repeat sequence enabled restriction enzyme digestion of PCR products to distinguish individual species within theL. braziliensiscomplex.     

REPRODUCTIVE CHARACTERISTICS OF THE FLOWER BREEDING DROSOPHILA HIBISCI BOCK (DROSOPHILIDAE) IN EASTERN AUSTRALIA: GENETIC AND ENVIRONMENTAL DETERMINANTS OF OVARIOLE NUMBER

Quantitative genetic analysis of the ovariole number of the Australian Hibiscus flower-breeding Drosophila hibisci Bock was conducted on populations from two localities along a latitudinal cline in ovariole number previously observed in the species (Starmer et al., in press). Parental strains, F₁, F_1r (reciprocal), F₂, backcross, and backcross reciprocal generations were used in a line-cross (generation means) analysis. This analysis revealed both additive and epistatic effects as important determinants of variation in ovariole number when larvae were reared at 25°C. Maternal effects and maternal-by-progeny genetic interactions were not significant. These results are comparable to previous studies that document epistatic components as genetic determinants of ovariole number in D. melanogaster. Parallel studies on ovariole number in D. hibisci parental and hybrid generations (F₁ and F_1r) reared as larvae at three temperatures (18°, 21.5°, and 25°C) showed environmental effects and genotype-by-environment interactions as significant influences on the phenotype. Maternal effects were present when temperature of larval development was considered and significant, nonlinear environmental effects were detected. Field collections of D. hibisci females showed that field conditions result in significant departure of ovariole number from comparable laboratory reared females. The significant epistatic genetic effects, genotype-by-environment interactions, and maternal effects indicate that the genetic architecture of traits, such as ovariole number, may be more complex than often acknowledged and thus may be compatible with Wright's view of a netlike relationship between the genome and complex characters (Wright 1968).     

Host Suitability of Selected Hybrids,Varieties and Inbreds of Corn to Populations of Meloidogyne spp.

Rates of reproduction of root-knot nematodes on corn varied with Meloidogyne species, with different populations of certain species, and with corn cultivars. M. arenaria, M. incognita and M. javanica reproduced at varying rates on all corn cultivars tested. None of the three selections of M. hapla reproduced on corn. Most of the Meloidogyne populations increased more rapidly on ''Coker'' and ''Pioneer'' hybrids than on ''McNair'' hybrids or on open-pollinated varieties or inbreds. Nematodes often reduced root growth, but the differences within given nematode-cultivar treatments were not usually significant. Root growth of ''Coker 911,'' which supported a high rate of reproduction, was affected less than ''Pioneer 309B'' which supported a low rate of nematode reproduction.     

Life on high: the diversity of small mammals at high altitude in South Africa

The Great Escarpment is the major mountain system in South Africa, yet very few biological surveys have been conducted outside of the well-known Drakensberg section. This is surprising given the important role that mountains play in local and global biodiversity patterns. In this study, small mammal diversity and community composition were estimated at three high altitude (>1,700?m) sites within the Sneeuberg Mountain Complex (SMC) of the Great Escarpment, South Africa from June 2009 to May 2010. The influences of selected environmental variables on diversity were also tested. Of 423 live-captures, a total of 292 unique individuals of 12 small mammal species (one shrew, one elephant shrew and 10 rodents) were identified during 5,280 trap nights. No single environmental variable could account for the variation observed in diversity measurements but vegetation height appeared to be the most important factor to influence the number of individuals captured. It is hypothesised that the high species richness and diversity of small mammals observed in the SMC compared to other parts of the Great Escarpment is due to the SMC being located in a transition zone of the Grassland and Nama-Karoo biomes. Our results suggest that the SMC could be important in conserving small mammal species from western and eastern assemblages across South Africa.     

Chimeric mitochondrial minichromosomes of the human body louse, Pediculus humanus: evidence for homologous and non-homologous recombination

The mitochondrial (mt) genome of the human body louse, Pediculus humanus, consists of 18 minichromosomes. Each minichromosome is 3 to 4 kb long and has 1 to 3 genes. There is unequivocal evidence for recombination between different mt minichromosomes in P. humanus. It is not known, however, how these minichromosomes recombine. Here, we report the discovery of eight chimeric mt minichromosomes in P. humanus. We classify these chimeric mt minichromosomes into two groups: Group I and Group II. Group I chimeric minichromosomes contain parts of two different protein-coding genes that are from different minichromosomes. The two parts of protein-coding genes in each Group I chimeric minichromosome are joined at a microhomologous nucleotide sequence; microhomologous nucleotide sequences are hallmarks of non-homologous recombination. Group II chimeric minichromosomes contain all of the genes and the non-coding regions of two different minichromosomes. The conserved sequence blocks in the non-coding regions of Group II chimeric minichromosomes resemble the "recombination repeats" in the non-coding regions of the mt genomes of higher plants. These repeats are essential to homologous recombination in higher plants. Our analyses of the nucleotide sequences of chimeric mt minichromosomes indicate both homologous and non-homologous recombination between minichromosomes in the mitochondria of the human body louse.     

Development of an in vitro colony formation assay for the evaluation of in vivo chemotherapy of a rat brain tumor.

An in vitro colony formation assay for the evaluation of in vivo brain tumor therapy has been developed. When plated, disaggregated cells derived from solid tumors proliferated to form relatively homogeneous colonies after a latency period of 2 to 6 days. Increasing concentrations of fetal calf serum enhanced colony-forming efficiency (CFE) with a plateau between 7 and 16%. Supplementation with either irradiated feeder cells (10(3) to 10(5) cells per dish), or medium conditioned by 1 to 3 days of in vitro incubation with the same cell line, doubled the CFE. The density of tumor cells (untreated or previously treated with chemotherapeutic agents) did not affect the CFE when a minimum of 10(4) total cells (tumor plus feeder) were plated. Therefore, in this system the optimal experimental conditions for evaluating chemotherapy and radiotherapy require incubation of disaggregated tumor cells for 12 days in medium containing 10% of fetal calf serum and enough feeder cells to provide a minimum of 10(4) cells per dish. The CFE for untreated tumors was 18 +/- 10% (+/-S.D.), demonstrating that there is significant biological variation. The assay appeared sensitive, with reproducible results, when applied to individual chemically treated tumors. An estimate of the percentage of clonogenic cells affected by in vivo chemotherapy may be obtained by comparing the CFE of cells from treated and untreated tumors. This assay can measure up to a 5 log(10) cell kill, and it should prove to be valuable in developing more effective regimens for the treatment of solid tumors in animals and man.     

Mechanosensitive Properties of BK Channels from Embryonic Rat Neuroepithelium

The mechanosensitive properties of large-conductance Ca²⁺-activated K⁺ (BK) channels from embryonic rat neuroepithelium were investigated with the cell-attached and inside-out configurations of the patch-clamp technique. The channels were activated in both recording configurations by negative pressures applied to the patch electrode, but reversal of the effect was total and immediate in inside-out patches whereas it was incomplete and delayed in on-cell patches. This mechanosensitivity was not mediated by Ca²⁺ ions or fatty acids, suggesting that it is an intrinsic property of these channels. Cytochalasin B did not affect mechanosensitivity in on-cell patches but increased it in inside-out patches. Kinetic studies showed that stretch increased the mean open time of the channels and decreased the slowest time constant of their closed-time distributions. The present as well as previous results suggest complex interactions between embryonic BK channels and their membranous and submembranous environment. Received: 1 February 1996/Revised: 25 March 1996