Species richness coincidence: conservation strategies based on predictive modelling

The present-day geographic distribution of individual species of five taxonomic groups (plants, dragonflies, butterflies, herpetofauna and breeding birds) is relatively well-known on a small scale (5 × 5 km squares) in Flanders (north Belgium). These data allow identification of areas with a high diversity within each of the species groups. However, differences in mapping intensity and coverage hamper straightforward comparisons of species-rich areas among the taxonomic groups. To overcome this problem, we modelled the species richness of each taxonomic group separately using various environmental characteristics as predictor variables (area of different land use types, biotope diversity, topographic and climatic features). We applied forward stepwise multiple regression to build the models, using a subset of well-surveyed squares. A separate set of equally well-surveyed squares was used to test the predictions of the models. The coincidence of geographic areas with high predicted species richness was remarkably high among the four faunal groups, but much lower between plants and each of the four faunal groups. Thus, the four investigated faunal groups can be used as relatively good indicator taxa for one another in Flanders, at least for their within-group species diversity. A mean predicted species diversity per mapping square was also estimated by averaging the standardised predicted species richness over the five taxonomic groups, to locate the regions that were predicted as being the most species-rich for all five investigated taxonomic groups together. Finally, the applicability of predictive modelling in nature conservation policy both in Flanders and in other regions is discussed.     

Mutations in the<Emphasis Type="Italic"> HLA</Emphasis> class II genes leading to loss of expression of HLA-DR and HLA-DQ in diffuse large B-cell lymphoma

Loss of expression of human leukocyte antigen (HLA) class II molecules on tumor cells affects the onset and modulation of the immune response through lack of activation of CD4+ T lymphocytes. Previously, we showed that the frequent loss of expression of HLA class II in diffuse large B-cell lymphoma (DLBCL) of the testis and the central nervous system (CNS) is mainly due to homozygous deletions in the HLA region on chromosome band 6p21.3. A minority of cases showed hemizygous deletions or mitotic recombination, implying that mutation of the remaining copy of the class II genes might be involved. Here, we studied three DLBCLs with loss of HLA-DQ expression for mutations in the DQB1 and DQA1 genes and three tumors with loss of HLA-DR expression for mutations in the DRB1 and DRA genes. In one case, a point mutation in exon 2 of the DQB1 gene, leading to the formation of a stop codon, was detected at position 47. In a second case, a stop codon was found at position 11 due to a deletion of 19 bp in exon 1 of the DRA gene. No mutations were found in the promoter sequences of the DRA, DQA1 and DQB1 genes. We conclude that both homozygous deletions and hemizygous deletions or mitotic recombination with mutations of the remaining allele may lead to loss of expression of the HLA class II genes, which is comparable to the mechanisms affecting HLA class I expression in solid cancers.     

Cloning,sequencing and phylogenetic/phenetic classification of an estrogen receptor alpha (alpha) subtype of sheepshead minnow (Cyprinodon variegatus)

The estrogen receptor (ER) is a key component of the reproductive system of both teleosts and tetrapods. In this study, the sequence and evolutionary relationship of sheepshead minnow (Cyprinodon variegatus) ER were examined. Total RNA from livers of adult laboratory-reared gravid female C. variegatus was reverse-transcribed to prepare cDNA. Nested pairs of gene-specific degenerative primers derived from conserved amino acid sequences of the ER DNA binding domain were used to amplify an internal fragment of the ER cDNA of C. variegatus using polymerase chain reaction (PCR) followed by rapid amplification of cDNA ends (RACE). The amplified cDNA products were inserted into pGEM T-Easy Vector for cloning and sequencing. The cloned ER cDNA segments gave a 524-amino-acid ER sequence, which represents approximately 80% of the sequence. The use of PHYLIP for phylogenetic analysis with the maximum parsimony method and for phenetic analysis with the neighbor-joining method, along with bootstrap resampling, using 24 known sequences of alpha and beta ER subtypes (both teleosts and tetrapods) indicated that the ER cDNA sequence of C. variegatus has strong homology to the alpha-subtype (ER alpha) of other teleostean fish, especially the closely related killifish species, Japanese medaka (Oryzias latipes). Because ER alpha was the only subtype found, it appears that the alpha-subtype is predominant in C. variegatus liver.     

Phosphorylation or glutamic acid substitution at protein kinase C sites on cardiac troponin I differentially depress myofilament tension and shortening velocity

There is evidence that multi-site phosphorylation of cardiac troponin I (cTnI) by protein kinase C is important in both long- and short-term regulation of cardiac function. To determine the specific functional effects of these phosphorylation sites (Ser-43, Ser-45, and Thr-144), we measured tension and sliding speed of thin filaments in reconstituted preparations in which endogenous cTnI was replaced with cTnI phosphorylated by protein kinase C-epsilon or mutated to cTnI-S43E/S45E/T144E, cTnI-S43E/S45E, or cTnI-T144E. We used detergent-skinned mouse cardiac fiber bundles to measure changes in Ca(2+)-dependence of force. Compared with controls, fibers reconstituted with phosphorylated cTnI, cTnI-S43E/S45E/T144E, or cTnI-S43E/S45E were desensitized to Ca(2+), and maximum tension was as much as 27% lower, whereas fibers reconstituted with cTnI-T144E showed no change. In the in vitro motility assay actin filaments regulated by troponin complexes containing phosphorylated cTnI or cTnI-S43E/S45E/T144E showed both a decrease in Ca(2+) sensitivity and maximum sliding speed compared with controls, whereas filaments regulated by cTnI-S43E/S45E showed only decreased maximum sliding speed and filaments regulated by cTnI-T144E demonstrated only desensitization to Ca(2+). Our results demonstrate novel site specificity of effects of PKC phosphorylation on cTnI function and emphasize the complexity of modulation of the actin-myosin interaction by specific changes in the thin filament.     

An amino acid in the central catalytic domain of three retroviral integrases that affects target site selection in nonviral DNA

Integrase can insert retroviral DNA into almost any site in cellular DNA; however, target site preferences are noted in vitro and in vivo. We recently demonstrated that amino acid 119, in the alpha2 helix of the central domain of the human immunodeficiency virus type 1 integrase, affected the choice of nonviral target DNA sites. We have now extended these findings to the integrases of a nonprimate lentivirus and a more distantly related alpharetrovirus. We found that substitutions at the analogous positions in visna virus integrase and Rous sarcoma virus integrase changed the target site preferences in five assays that monitor insertion into nonviral DNA. Thus, the importance of this protein residue in the selection of nonviral target DNA sites is likely to be a general property of retroviral integrases. Moreover, this amino acid might be part of the cellular DNA binding site on integrase proteins.     

Quantitative determination of free intracellular alpha-keto acids in neutrophils

For the first time, a procedure is described for the quantitative analysis of free alpha-keto acid content in human neutrophils (PMNs) relative to single cell number by reversed-phase fluorescence high-performance liquid chromatography. The procedure is minimally invasive and is unsurpassed in the quality of PMN separation, ease of sample preparation as well as sample stability. This method can satisfy the rigorous demands for an ultra-sensitive, comprehensive and rapid intracellular alpha-keto acid analysis in particularly for the surveillance of severe diseases as well as cellular or organ dysfunction.