Allometry in the placoderm Bothriolepis canadensis and its significance to antiarch evolution

A set of 18 measurements of the dermal armour of Bothriolepis canadensis Whiteaves (Placodermi, Anti-archa) is analysed with respect to allometric growth patterns. The strongest allometric patterns were found for the orbital fenestra and premedian plate of the head-shield. and the anterior median dorsal plate of the trunk-shield. These are all areas of the greatest importance in antiarch phylogeny and imply a role for ontogenetic effects such as paedomorphosis in the evolution of antiarchs. It is suggested that this is partly a result of the severe constraints on growth in a closed box such as the armour of placoderms, and may be generally true of such arrangements.     

The genomic instability of yeast cdc6-1/cdc6-1 mutants involves chromosome structure and recombination

When diploid cells of Saccharomyces cerevisiae homozygous for the temperature-sensitive cell division cycle mutation cdc6-1 are grown at a semipermissive temperature they exhibit elevated genomic instability, as indicated by enhanced mitotic gene conversion, mitotic intergenic recombination, chromosomal loss, chromosomal gain, and chromosomal rearrangements. Employing quantitative Southern analysis of chromosomes separated by transverse alternating field gel electrophoresis (TAFE), we have demonstrated that 2N-1 cells monosomic for chromosome VII, owing to the cdc6-1 defect, show slow growth and subsequently yield 2N variants that grow at a normal rate in association with restitution of disomy for chromosome VII. Analysis of TAFE gels also demonstrates that cdc6-1/cdc6-1 diploids give rise to aberrant chromosomes of novel lengths. We propose an explanation for the genomic instability induced by the cdc6-1 mutation, which suggests that hyper-recombination, chromosomal loss, chromosomal gain and chromosomal rearrangements reflect aberrant mitotic division by cdc6-1/cdc6-1 cells containing chromosomes that have not replicated fully.     

10-Hydroxy-7,8-dihydropyrazino[1',2':1,5]pyrrolo[2,3-d]pyridazine-1,9(2H,6H)-diones: potent, orally bioavailable HIV-1 integrase strand-transfer inhibitors with activity against integrase mutants

A series of 10-hydroxy-7,8-dihydropyrazino[1',2':1,5]pyrrolo[2,3-d]pyridazine-1,9(2H,6H)-diones was synthesized and tested for their inhibition of HIV-1 replication in cell culture. Structure-activity studies indicated that high antiviral potency against wild-type virus as well as viruses containing integrase mutations that confer resistance to three different structural classes of integrase inhibitors could be achieved by incorporation of small aliphatic groups at certain positions on the core template. An optimal compound from this study, 16, inhibits integrase strand-transfer activity with an IC(50) value of 10 nM, inhibits HIV-1 replication in cell culture with an IC(95) value of 35 nM in the presence of 50% normal human serum, and displays modest pharmacokinetic properties in rats (i.v. t(1/2)=5.3 h, F=17%).     

A toll-like receptor 2 pathway regulates the Ppargc1a/b metabolic co-activators in mice with Staphylococcal aureus sepsis

Activation of the host antibacterial defenses by the toll-like receptors (TLR) also selectively activates energy-sensing and metabolic pathways, but the mechanisms are poorly understood. This includes the metabolic and mitochondrial biogenesis master co-activators, Ppargc1a (PGC-1α) and Ppargc1b (PGC-1β) in Staphylococcus aureus (S. aureus) sepsis. The expression of these genes in the liver is markedly attenuated inTLR2(-/-) mice and markedly accentuated in TLR4(-/-) mice compared with wild type (WT) mice. We sought to explain this difference by using specific TLR-pathway knockout mice to test the hypothesis that these co-activator genes are directly regulated through TLR2 signaling. By comparing their responses to S. aureus with WT mice, we found that MyD88-deficient and MAL-deficient mice expressed hepatic Ppargc1a and Ppargc1b normally, but that neither gene was activated in TRAM-deficient mice. Ppargc1a/b activation did not require NF-kβ, but did require an interferon response factor (IRF), because neither gene was activated in IRF-3/7 double-knockout mice in sepsis, but both were activated normally in Unc93b1-deficient (3d) mice. Nuclear IRF-7 levels in TLR2(-/-) and TLR4(-/-) mice decreased and increased respectively post-inoculation and IRF-7 DNA-binding at the Ppargc1a promoter was demonstrated by chromatin immunoprecipitation. Also, a TLR2-TLR4-TRAM native hepatic protein complex was detected by immunoprecipitation within 6 h of S. aureus inoculation that could support MyD88-independent signaling to Ppargc1a/b. Overall, these findings disclose a novel MyD88-independent pathway in S. aureus sepsis that links TLR2 and TLR4 signaling in innate immunity to Ppargc1a/b gene regulation in a critical metabolic organ, the liver, by means of TRAM, TRIF, and IRF-7.     

Association of immune parameters with clinical outcome in stage III colon cancer: results of Southwest Oncology Group Protocol 9009

Levamisole (LMS), utilized in the adjuvant treatment of patients with stage III colon cancer, is immunomodulatory. To determine whether alterations in immune parameters before, during and after 12 months of 5FU/LMS therapy correlate with disease-free survival, 38 patients enrolled on Southwest Oncology Group (SWOG) protocol 8899 received extensive lymphocyte phenotypic analysis prior to therapy and 3, 6, 12 and 15 months after treatment initiation. The median follow-up of patients is 41 months. Significant increases in the proportion and total number of CD56⁺ natural killer cells were seen, starting at 3 months and continuing until 15 months (P < 0.001). Increases in the total numbers of cells expressing CD25 (interleukin-2 receptor), VLA4 and the combinations of CD4: CD45RA and CD4:CDw29 were not evident during therapy but were seen at 15 months (P < 0.05: CD25, CD4:CDw29, CD4:CD45RA; P < 0.001: VLA4). Low levels of CD8⁺ cells prior to treatment initiation and after 3 months of therapy correlated with early relapse within the first year of 5FU/LMS treatment. Patients who have remained disease-free (n = 22, median follow-up 45 months) demonstrated increases in the total numbers of CD8⁺, CD25⁺, CD56⁺, VLA4⁺, CD4: CDw29 and CD4:CD45RA cells, primarily at 15 months. In contrast, patients who relapsed had decreased numbers of CD8⁺, CD4:CDw29, CD4: CD45RA and VLA4⁺ cells and minimal increases in CD56⁺ and CD25⁺ cells. Statistically significant differences between the late-relapse group and the group remaining disease-free were seen for CD25⁺, CD4: CD45RA and CD4:CDw29 cells at the 15-month assay time (P = 0.0276, P = 0.0349, P = 0.0178 respectively). In conclusion, multiple alterations in lymphocyte phenotype, with increases in the proportion and total number of cells involved in cell-mediated immune responses, were seen during and especially following completion of therapy with 5FU/LMS. Many of these changes are significantly associated with clinical outcome and may be useful for risk stratification of stage III colon cancer patients following completion of adjuvant therapy. Received: 9 July 1999 / Accepted: 11 August 1999     

Using spider web types as a substitute for assessing web-building spider biodiversity and the success of habitat restoration

Arthropods have been regarded as good indicators of habitat quality due to their sensitivity to changes in habitat state. However, there are many constraints to working with arthropods that make them inaccessible to land managers and most volunteer-driven initiatives. Our study examined a novel approach for detecting changes in web-building spider communities by focussing on the types of webs that spiders build rather than the spider itself. This method was cost-effective, easy-to-use, and importantly, we found a strong congruency between the diversity of web architecture and the diversity of web-building spider genera. The metrics derived from this method could distinguish differences in web-building communities among habitat types that represented a successional gradient, and thus we concluded that the method was useful for monitoring the progress of restoration. Many other applications for the method are possible such as environmental impact assessment and agricultural pest management, and we encourage development in these areas.     

Isopentenyl-diphosphate isomerase is essential for viability of <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis>

Homozygosity for a mutation in the idi-1 gene of Caenorhabditis elegans results in paralysis during the first larval stage, followed by an arrest of growth and development late in the first larval stage. Apoptotic corpses, which are apparently the result of normal programmed cell death, persist in the arrested larvae. In genetic mosaics, an additional defect becomes evident upon examination with Nomarski optics: cells that are genotypically mutant enlarge, and their cytoplasm becomes dimpled. Electron microscopy indicates that the dimpling reflects an accumulation of many enlarged lysosomes and autophagosomes. The mosaics demonstrate that the lethal mutation acts cell autonomously with respect to this vesicular abnormality and that there is a maternal effect with respect to the time of developmental arrest of mutant progeny. Cloning of the gene reveals that it is the only gene in C. elegans for isopentenyl-diphosphate isomerase, an enzyme that is important for the synthesis of lipophilic molecules, including farnesyl and geranyl diphosphates.     

Homologs of the yeast neck filament associated genes: isolation and sequence analysis of Candida albicans CDC3 and CDC10

Morphogenesis in the yeast Saccharomyes cerevisiae consists primarily of bud formation. Certain cell division cycle (CDC) genes, CDC3, CDC10, CDC11, CDC12, are known to be involved in events critical to the pattern of bud growth and the completion of cytokinesis. Their products are associated with the formation of a ring of neck filaments that forms at the region of the mother cell-bud junction during mitosis. Morphogenesis in Candida albicans, a major fungal pathogen of humans, consists of both budding and the formation of hyphae. The latter is thought to be related to the pathogenesis and invasiveness of C. albicans. We have isolated and characterized C. albicans homologs of the S. cerevisiae CDC3 and CDC10 genes. Both C. albicans genes are capable of complementing defects in the respective S. cerevisiae genes. RNA analysis of one of the genes suggests that it is a regulated gene, with higher overall expression levels during the hyphal phase than in the yeast phase. Not surprisingly, DNA sequence analysis reveals that the proteins share extensive homology at the amino acid level with their respective S. cerevisiae counterparts. Related genes are also found in other species of Candida and, more importantly, in filamentous fungi such as Aspergillus nidulans and Neurospora crassa. A database search revealed significant sequence similarity with two peptides, one from Drosophila and one from mouse, suggesting strong evolutionary conservation of function.     

Mapping X-linked ophthalmic diseases: II. Linkage relationship of X-linked retinitis pigmentosa to X chromosomal short arm markers

Summary X-linked retinitis pigmentosa (XLRP) is a series of hereditary dystrophic diseases of the retina that occur in three clinically distinguishable variants: the classic form (McK-31360), a type known as choroidoretinal dystrophy (McK-30330), and a variant with golden-metallic or tapetal reflex in the heterozygote (McK30320). Controversy exists as to whether these phenotypic differences are due to clinical variability in disease expression, heterogeneity in disease alleles at a single locus, or a multiplicity of loci for XLRP. We have studied a single large kindred segregating for XLRP with the metallic fundus reflex in the heterozygote with restriction fragment length polymorphisms (RFLPs) from the short arm of the human X chromosome, and found measurable linkage to DXS7 (=12.5 cMorgans at LOD=2.5), the same RFLP previously shown by others to be tightly linked to the other forms of XLRP at =3cM. Although these estimates appeared to be different, each fell just within the 95% probability interval of the other and, therefore, were insufficient to prove or disprove that the metallic sheen form of XLRP is allelic with other forms of XLRP. Additional RFLPs at the DXS43 and the ornithine transcarbamoylase loci provided three-point crosses for determining the relative positions of DXS7 and XLRP, and supported an order that placed this form of XLRP distal to DXS7 on the Xp. Until the question of genetic heterogeneity is resolved, careful phenotypic characterization of the clinical type of XLRP present in families being used for linkage analyses is advisable.Presented in part at the American Society of Human Genetics meeting, Toronto, Canada, November 1, 1984