Predator–prey ratios on cocoa along a land-use gradient in Indonesia

Tropical landscapes are dominated by agroecosystems, but the potential value of agroecosystems for the survival of species is often overlooked. In agroecosystems, species conservation is especially important when functional groups such as predators are affected. In Central Sulawesi, we sampled arthropods on cocoa in a gradient of land-use intensity from extensively used forest gardens to intensively used agroforestry systems. The abundance and diversity of all arthropods did not correlate with land-use intensity, so human impact was not followed by high species losses. However, the number of species and abundance of the phytophagous arthropods increased and that of the entomophagous arthropods decreased with land-use intensity. The reduced predator–prey ratio in intensified systems can be related to their reduced species richness of shade trees and the changed microclimate (increased temperature, decreased humidity and canopy cover). In conclusion, transformation of traditional into intensified agroforestry systems had a great impact on arthropod community structure on cocoa. Since predator–prey ratios decreased with increasing land-use intensity, local farmers should have least pest problems in the traditionally diversified agroforestry systems.     

DHPLC-based germline mutation screening in the analysis of the VHL tumor suppressor gene: usefulness and limitations

In order to evaluate the sensitivity and specificity of the recently introduced high-throughput method DHPLC (denaturing high performance liquid chromatography) for mutation screening in the VHL tumor suppressor gene, we subjected DNA from 43 unrelated VHL patients with previously sequenced VHL germline mutations to this method. In addition, 36 genomic DNAs of unrelated individuals suspected of being VHL carriers but with unknown germline status were analyzed by DHPLC and sequencing. The aims of the present study were to compare mutation results obtained by direct sequencing and DHPLC, and a comparison of two different DHPLC systems. The sensitivity of DHPLC was tested with two commercial devices and protocols, i.e., the Varian-Helix system and the Wave Nucleic Acid Fragment Analysis system. Both resolved all but one mutation in exons 2 and 3 of the VHL gene. In contrast, the GC-rich exon 1 showed discrepancies in the rate of mutation detection. Whereas the Varian-Helix system detected 10/15 (67%) of the known mutations, the Wave Nucleic Acid Fragment Analysis system detected 13/14 (93%). All three mutations in samples with unknown mutation status were revealed by both systems raising the mutation detection rate to 72% and 94%, respectively. Cases with different substitutions at the same nucleotide showed different elution profiles, but similar elution profiles could be obtained from different mutations. The Wave Nucleic Acid Fragment Analysis system detected most VHL mutations; however, when a 100% detection rate is needed, sequencing is still required and must therefore be the standard VHL mutation detection procedure. Once a family-specific mutation has been established, DHPLC may be suitable for the rapid and cost-effective determination of VHL carrier status in family members.     

Impact of Bacillus popilliae,Rickettsiella popilliae and entomopathogenic nematodes on a population of the scarabaeid,Cyclocephala hirta

Larvae of the scarabaeid, Cyclocephala hirta, are major pests of turfgrass in California. A field test was conducted against third instars that included the following treatments: untreated control; chemical insecticide (bendiocarb); milky disease bacterium (Bacillus popilliae); and entomopathogenic nematodes (Steinernema feltiae and Heterorhabditis bacteriophora). There were no significant differences in population reduction among the treatments, but the larval population in all plots showed a dramatic decline. The C. hirta population had a natural occurrence of milky disease and blue disease caused by Rickettsiella popilliae. The prevalence of blue disease during the course of the study averaged < 10% but that of milky disease averaged about 20%. More significantly, the soil from all treatment plots when bioassayed for B. popilliae showed that 67–90% of the larvae became infected with this bacterium. None of the larvae became infected with the blue disease organism. We conclude that B. popilliae was occurring in epizootic proportions in our field tests and was a significant mortality factor in causing the decline of the C. hirta population.     

Effect of anticoagulants in vitro on the viability of lymphocytes and content of free fatty acids in plasma

Summary These authors attempted to test the effect of anticoagulants on lymphocytes viability by reproducing the procedure used for lymphocyte isolation for various immunologic tests in which blood specimens are allowed to stay at room temperature for 2 h before lymphocytes are isolated. Blood was obtained with three different anticoagulants i.e. heparin, citrate, and CPDA (citrate, phosphate, dextrose, and adenine). Plasma was lyophilized and extracted with ethanol. Dried ethanol extracts were suspended in medium (RPMI 1640+10% fetal bovine serum) and incubated with a lymphocyte cell line (MOLT-4). After 24 h of incubation the viability of cells was examined. The following death rates of the cells were observed: heparin −63±4.6% (mean±SEM), citrate −27±6.7%, and CPDA 6.2±0.6% (P<0.0005). A significant correlation was found between these results and changes in the concentrations of free fatty acids in the extracts. These results emphasize the importance of choosing the right anticoagulant when the viability of lymphocytes is obligatory.     

Epstein-Barr virus (EBV) receptors, complement receptors, and EBV infectibility of different lymphocyte fractions of human peripheral blood. I. Complement receptor distribution and complement binding by separated lymphocyte subpopulations.

Human peripheral lymphocytes were fractionated into a variety of B-, T-, and O-cell fractions and were characterized with regard to several surface receptors. There was a strong correlation between the frequency of EAC receptor-positive cells and the percentage of complement membrane fluorescence (CMF)-stained cells following exposure to fresh human serum and subsequent staining with an anti-C3 conjugate. CMF staining did not diminish in C4-deficient or hypogammaglobulinemic serum, or in the presence of EDTA or EGTA-Mg²⁺, but was completely negative with C3-depleted normal human serum. In all likelihood, the staining is therefore due to the direct binding of C3 to preformed receptors on the lymphocyte surface. In addition to the surface Ig-positive B-cell fractions, C3 receptors were also detected on part of the O-cell population and on a proportion of the Fc receptor-positive T cells.     

Primary structure and features of the genome of the Lactobacillus gasseri temperate bacteriophage (phi)adh.

The complete DNA sequence of the Lactobacillus (Lb.) gasseri temperate phage (phi)adh was determined. The linear and double-stranded genome consists of 43.785bp with a G+C content of 35. 3% and 3' protruding cohesive ends of 12nt. Sixty-two possible ORFs were identified. On the basis of homology comparisons, some of them could be assigned to possible functions, such as a helicase, a nucleic acid polymerase and a protease. In a non-coding area of the (phi)adh genome, structural features of a potential replication origin were detected. After subcloning, this region was functional as a replicon in Lb. gasseri and Lactococcus lactis. N-terminal aa sequencing and electron microscopic analysis of intact and defective phage particles enabled the identification of two capsid protein genes. One of their products, the major head protein, seems to be processed on the posttranslational level.