Molecular genetic evidence of formosan subterranean termite (Isoptera: Rhinotermitidae) colony survivorship after prolonged inundation

Levee breaches because of Hurricane Katrina in 2005 inundated 80% of the city of New Orleans, LA. Formosan subterranean termites were observed actively foraging within in-ground monitoring stations within months after this period of flooding. It was unknown if the activity could be attributed to preexisting colonies that survived inundation or to other colonies surviving flooding by being located at higher elevations readily invading these territories. Genotypic profiles of 17 termite colonies collected from eight inundated locations before flooding were compared with termite colonies after flooding from the same locations to determine Formosan subterranean termite survival after sustained flooding. Results indicate that 14 colonies were able to survive inundation for extended periods.     

Identification of the fibroblast growth factor (FGF)-interacting domain in a secreted FGF-binding protein by phage display

Fibroblast growth factor-binding proteins (FGF-BP) are secreted carrier proteins that release fibroblast growth factors (FGFs) from the extracellular matrix storage and thus enhance FGF activity. Here we have mapped the interaction domain between human FGF-BP1 and FGF-2. For this, we generated T7 phage display libraries of N-terminally and C-terminally truncated FGF-BP1 fragments that were then panned against immobilized FGF-2. From this panning, a C-terminal fragment of FGF-BP1 (amino acids 193-234) was identified as the minimum binding domain for FGF. As a recombinant protein, this C-terminal fragment binds to FGF-2 and enhances FGF-2-induced signaling in NIH-3T3 fibroblasts and GM7373 endothelial cells, as well as mitogenesis and chemotaxis of NIH-3T3 cells. The FGF interaction domain in FGF-BP1 is distinct from the heparin-binding domain (amino acids 110-143), and homology modeling supports the notion of a distinct domain in the C terminus that is conserved across different species. This domain also contains conserved positioning of cysteine residues with the Cys-214/Cys-222 positions in the human protein predicted to participate in disulfide bridge formation. Phage display of a C214A mutation of FGF-BP1 reduced binding to FGF-2, indicating the functional significance of this disulfide bond. We concluded that the FGF interaction domain is contained in the C terminus of FGF-BP1.     

The β-lactam-sensitive d,d-carboxypeptidase activity of Pbp4 controls the l,d and d,d transpeptidation pathways in Corynebacterium jeikeium

Corynebacterium jeikeium is an emerging nosocomial pathogen responsible for vascular catheters infections, prosthetic endocarditis and septicemia. The treatment of C. jeikeium infections is complicated by the multiresistance of clinical isolates to antibiotics, in particular to β-lactams, the most broadly used class of antibiotics. To gain insight into the mechanism of β-lactam resistance, we have determined the structure of the peptidoglycan and shown that C. jeikeium has the dual capacity to catalyse formation of cross-links generated by transpeptidases of the d , d and l , d specificities. Two ampicillin-insensitive cross-linking enzymes were identified, Ldt_Cjk1, a member of the active site cysteine l , d -transpeptidase family, and Pbp2c, a low-affinity class B penicillin-binding protein (PBP). In the absence of β-lactam, the PBPs and the l , d -transpeptidase contributed to the formation of 62% and 38% of the cross-links respectively. Although Ldt_Cjk1 and Pbp2C were not inhibited by ampicillin, the participation of the l , d -transpeptidase to peptidoglycan cross-linking decreased in the presence of the drug. The specificity of Ldt_Cjk1 for acyl donors containing a tetrapeptide stem accounts for this effect of ampicillin since the essential substrate of Ldt_Cjk1 was produced by an ampicillin-sensitive d , d -carboxypeptidase (Pbp4_Cjk). Acquisition and mutational alterations of pbp2C accounted for high-level β-lactam resistance in C. jeikeium .     

A cyclophilin gene marker confirming geographical differentiation of Norway spruce populations and indicating viability response on excess soil-born salinity

A newly identified cyclophilin-encoding cDNA clone was used to design a codominant inherited EST-PCR marker in Norway spruce. The study of the current minor polymorphism revealed a geographically structured differentiation pattern across 17 test populations, showing a slight clinal variation south-north through Europe. Based on the frequency of alleles, isolation-by-distance analysis and the Ewens-Watterson test, we conclude that a selectively neutral random-drift mutation recently occurred within the Alpine population group, thus being responsible for the genetic variation detected. Analysis of tolerant and susceptible subsets of two adjacent Bavarian spruce populations affected by soil-born NaCl pollution, revealed that the cyclophilin marker locus also confirms biased genotype frequencies. Considering an unlinked PCR marker of a ribosomal protein-encoding EST clone, deviations between pooled tolerant subsets and pooled sensitive subsets were proven to be more significant for two-locus homozygous genotypes than for each locus alone. We suggest that both loci are linked to adaptive genomic regions. Their potential to test the feasibility of marker-assisted selection of both NaCl-tolerant and drought resistant tree populations is discussed.     

Relationships in the Drosophila obscura species group, inferred from mitochondrial cytochrome oxidase II sequences

We compare the sequences for the mitochondrial cytochrome oxidase II gene of 13 species of the Drosophila obscura group. The survey includes six members of the D. affinis subgroup, four of the D. pseudoobscura subgroup, and three of the D. obscura subgroup. In all species, the gene is 688 nucleotides in length, encoding a protein of 229 amino acids plus the first position T of the stop codon. The sequences show the typical high-transition bias for closely related species, but that bias is essentially eliminated for species pairs of > 5% sequence divergence. The phylogenetic relationships in the species group are inferred using both neighbor-joining and maximum parsimony. The two procedures give comparable results, showing that the D. affinis and D. pseudoobscura subgroups are monophyletic groupings that appear to have closer affinities to one another than either has to the D. obscura subgroup. We use transversion distances to estimate times of divergence, on the basis of three different estimates of the time of separation of the D. obscura species group from the D. melanogaster group. If that event occurred 35 Mya, then we can estimate the origin of the nearctic forms at approximately 22 Mya and the separation of the D. affinis and D. pseudoobscura subgroups at approximately 17 Mya.      

土曲霉金色变种AT8951菊粉酶的纯化和性质的研究

土典霉金色变种AT8951菊粉酶粗酶液经硫酸铵分段沉淀、DEAE Cellulose DE32离子交换、超滤、Sephadex G-150凝胶过滤和FPLC,获得两个菊粉酶组分EⅠ和EⅡ,经分析型FPLG和PAGE鉴定为单一纯和分析纯。EⅠ分子量为66KD,最适作用温度和pH分别55℃和5.8;EⅡ分子量为56KD,最适作用温度为57℃,最适pH为6.0。EⅠ和EⅡ皆为糖蛋白,多糖含量分别为24.7％和22％,都属于内切酶。本文还对EⅠ和EⅡ的Km值和I/s值,温度、pH、离子对酶活作用的影响等进行了研究。     

De novo complex chromosome rearrangement: a study of two patients

Complex chromosome rearrangements (CCR) involving multiple breaks in two or more chromosomes are rare. We describe a girl with development delay and overgrowth who presents a nine-break apparently balanced de novo rearrangement involving chromosomes 1, 2, 3, 4 and 12, and a boy with developmental delay and seizures with a complex three-chromosome apparently balanced de novo rearrangement involving chromosomes 2, 7 and 13. The relationship between clinical abnormalities and apparently balanced rearrangements is discussed.