Neuroanatomy in fragile X females: the posterior fossa.

The relative homogeneity of the neuropsychiatric phenotype in individuals with fragile (fra) X syndrome suggests that there are consistent central nervous system (CNS) abnormalities underlying the observed cognitive and behavioral abnormalities. In this study, the neuroanatomy of the posterior fossa and other selected CNS regions in 12 young fra X females were compared with those of a group of 12 age-, sex-, and IQ-matched females without evidence of the fra X syndrome. Fra X females were shown to have decreased size of the posterior cerebellar vermis and increased size of the fourth ventricle, findings that are identical to those previously reported for fra X males. When compared with fra X male and nonfra X control groups, the distribution of the posterior-vermis and fourth-ventricle variables for the fra X female group was intermediate. These results support the hypothesis that the fra X genetic abnormality leads to hypoplasia of the posterior cerebellar vermis, a neuroanatomical variation of potential importance to both developmental and neuropsychiatric syndromes.     

Mycorrhizal fungal spore community structure in a manipulated prairie

Most plant communities support a diverse assemblage of arbuscular mycorrhizal fungi (AMF). AMF communities have the potential to affect plant community structure and vice versa. We examined AMF sporulation in a 4.5‐ha reconstructed prairie in Eau Claire County, Wisconsin. In fall 2003, the site was planted with varied numbers and combinations of native prairie species from four functional guilds: C₃ grasses/sedges, C₄ grasses, legume, and nonleguminous forbs. We hypothesized that more diverse plant seeding mixtures would promote AMF diversity. To examine the interaction between plant and fungal communities, plots were divided and subplots treated with the fungicide chlorothalonil to suppress AMF, enriched with ammonium nitrate fertilizer, treated with both fungicide and nitrogen, or remained untreated (control). Soil samples were collected during the summers of 2004, 2006, and 2007 from each subplot. Spores of AMF were extracted, identified to species, and enumerated. Initial plant seeding diversity did not significantly influence spore abundance, fungal diversity, plant productivity, or plant richness 4 years after establishment. Fungal species richness was positively, but weakly, correlated with plant productivity (r² = 0.11) and plant richness (r² = 0.09). Fungal community composition changed significantly over time; nitrogen addition, fungicide application, and site characteristics also shaped community composition. After 4 years of treatment, nitrogen and fungicide reduced AMF richness, changed sporulation patterns among AMF taxa, and reduced diversity and productivity in plant communities. Divergence in AMF community is being mirrored by changes in the plant community independent of initial seeding treatments, though causation could not be determined.     

Links between blood parasites,blood chemistry,and the survival of nestling American crows

Many studies have used the avian hemosporidians (Leucocytozoon, Plasmodium, and Hemoproteus) to test hypotheses of host–parasite co‐evolution, yet documented health and survival consequences of these blood parasites vary among studies and generalizations about their pathogenicity are debatable. In general, the negative effects of the hemosporidians are likely to be greatest during acute infections of young birds, yet most previous studies in wild passerines have examined chronic effects in adults. Here, we evaluated responses of nestling American crows (Corvus brachyrhynchos) to acute infection (prevalence and burden), as well as its short‐ and long‐term survival consequences. We used panel of nine hematological and biochemical parameters that are regularly used to evaluate the health of domestic animals, including leukocyte profiles, hematocrit, and plasma proteins. We assessed the effects of infection on survival in a mark‐recapture framework. Overall, 56% of crows (n = 321 samples) were infected by at least one of the three genera. Infections by all genera were associated with elevated plasma proteins and globulins, which could indicate an adaptive immune response. However, only Plasmodium infections were associated with low hematocrit (anemia) and lower fledging success, possibly mediated by the negative effect of low hematocrit values on body condition. Moreover, early Plasmodium infection (<40 days of age) had long‐term survival implications: it was associated with lower apparent survival probability within 3 years after fledging. These results suggest that young crows mounted an adaptive immune response to all three genera. Short‐ and long‐term pathological effects, however, were only apparent with Plasmodium infections.     

The insE open reading frame of IS1 is not required for formation of cointegrates.

The role of the insE open reading frame in transposition of IS1 was reexamined by using an insE nonsense mutation that does not alter the amino acid sequence of InsA inhibitor or InsAB transposase. The mutant was active in all strains tested, showing that insE is not essential for formation of cointegrates.     

The plastid aldolase gene fromChlamydomonas reinhardtii: Intron/exon organization, evolution, and promoter structure

Genomic clones encoding the plastidic fructose- 1,6-bisphosphate aldolase ofChlamydomonas reinhardtii were isolated and sequenced. The gene contains three introns which are located within the coding sequence for the mature protein. No introns are located within or near the sequence encoding the transit-peptide, in contrast to the genes for plastidic aldolases of higher plants. Neither the number nor the positions of the three introns of theC. reinhardtii aldolase gene are conserved in the plastidic or cytosolic aldolase genes of higher plants and animals. The 5 border sequences of introns in the aldolase gene ofC. reinhardtii exhibit the conserved plant consensus sequence. The 3 acceptor splice sites for introns 1 and 3 show much less similarity to the eukaryotic consensus sequences than do those of intron 2. The plastidic aldolase gene has two tandemly repeated CAAT box motifs in the promoter region. Genomic Southern blots indicate that the gene is encoded by a single locus in theC. reinhardtii genome.     

Studies of partially transforming polyomavirus mutants establish a role for phosphatidylinositol 3-kinase in activation of pp70 S6 kinase.

Infection of mouse fibroblasts by wild-type polyomavirus results in increased phosphorylation of ribosomal protein S6 (D.A. Talmage, J. Blenis, and T.L. Benjamin, Mol. Cell. Biol. 8:2309-2315, 1988). Here we identify pp70 S6 kinase (pp70S6K) as a target for signal transduction events leading from polyomavirus middle tumor antigen (mT). Two partially transforming virus mutants altered in different mT signalling pathways have been studied to elucidate the pathway leading to S6 phosphorylation. An upstream role for mT-phosphatidylinositol 3-kinase (PI3K) complexes in pp70S6K activation is implicated by the failure of 315YF, a mutant unable to promote PI3K binding, to elicit a response. This conclusion is supported by studies using wortmannin, a known inhibitor of PI3K. In contrast, stable interaction of mT with Shc, a protein thought to be involved upstream of Ras, is dispensable for pp70S6K activation. 250YS, a mutant mT which retains a binding site for PI3K but lacks one for Shc, stimulates pp70S6K to wild-type levels. Mutants 315YF and 250YS induce partial transformation of rats fibroblasts with distinct phenotypes, as judged from morphological and growth criteria. Neither mutant induces growth in soft agar, indicating that an increase in S6 phosphorylation, while necessary for cell cycle progression in normal mitogenesis, is not sufficient for anchorage-independent cell growth. In the polyomavirus systems, the latter requires integration of signals from mT involving both Shc and PI3K.     

Phosphorylation of middle T by pp60c-src: a switch for binding of phosphatidylinositol 3-kinase and optimal tumorigenesis

Substitution of phenylalanine for tyrosine 315 of the polyoma virus middle T (mT) protein lowers the incidence and limits the spectrum of tumors induced following inoculation of the virus into newborn mice. This substitution removes the major site of phosphorylation by pp60c-src without altering the ability of mT to associate with or to activate pp60c-src. The mutant mT fails to show binding of a phosphatidylinositol 3-kinase (Ptdlns 3-kinase) activity that is normally present in wild-type mT complexes. Furthermore, an anti-peptide antiserum that specifically recognizes mT lacking phosphate at tyrosine 315 precipitates binary (mT-pp60c-src) but not ternary (mT-pp60c-src-Ptdlns 3-kinase) complexes from wild-type infected cell extracts. Reprecipitation with either anti-pp60c-src or anti-mT serum brings down ternary complexes containing mT phosphorylated on tyrosine 315. Phosphorylation of mT by pp60c-src in vivo is therefore a critical event for binding of Ptdlns 3-kinase and for expression of the full tumorigenic potential of the virus.     

Blood glucose and serum insulin levels in lean and genetically obese mice.

Fed and 24 hour fasted lean and genetically obese mice (ob/ob) were given a fixed glucose load per gm body weight by intraperitoneal and intragastric administration. Intraperitoneal glucose injection into the obese mice produced a prolonged elevated blood glucose level with a concomitant significant decrease of circulating insulin. Possible interpretations of this observation are discussed. In those obese animals in which glucose was administered intragastrically the fed obese mice had a blood glucose concentration of 450-500 mg% for a period of one hour but there was no increase in circulating insulin, however, in the fasted obese mice in which the glucose concentration was about 350 mg% for one hour, there was a significant increase in the circulating insulin levels. The fed and fasted lean mice showed normal glucose tolerance curves and the expected increase in circulating insulin following either intraperitoneal orintragastric glucose loads. It is concluded that hyperglycaemia in the ob/ob mice is unlikely to be the principal cause of hyperinsulinaemia.     

α-Crystallin. The isolation and characterization of distinct macromolecular fractions

alpha-Crystallin was isolated from calf lens periphery by chromatography on DEAE-cellulose and gel filtration. Three distinct populations of macromolecules have been isolated with molecular weights in the ranges approx. 6x10(5)-9x10(5), 0.9x10(6)-4x10(6) and greater than 10x10(6). The concentration of macromolecules at the molecular-weight limits of a population are very low. The members of the different populations do not appear to be in equilibrium with each other. Further, in those molecular-weight fractions investigated, no equilibrium between members of the same population was observed. The population of lowest molecular weight comprises 65-75% of the total material. The amino acid and subunit composition of the different-sized fractions appear very similar, if not identical. The only chemical difference observed between the fractions is the presence of significant amounts of sugar in the higher-molecular-weight fractions. Subunit molecular weights of approx. 19.5x10(3) and 22.5x10(3) were observed for all alpha-crystallin fractions.