Direct and reflexive effects of nitric oxide synthase inhibition on blood pressure

Direct effects of vasoactive substances on blood pressure can be examined in individuals with tetraplegia due to disruption of descending spinal pathways to sympathetic preganglionic neurons, as cervical lesions interfere with baroreceptor reflex buffering of sympathetic outflow. In this study, we assessed effects of the nitric oxide synthase inhibitor nitro-L-arginine methyl ester (L-NAME) on mean arterial pressure, heart rate, and plasma norepinephrine concentrations in individuals with tetraplegia vs. effects shown in a neurologically intact control group. Seven individuals with tetraplegia and seven age-matched controls received, on separate visits and in the following order, placebo (30 ml normal saline) and 0.5, 1, 2, and 4 mg/kg L-NAME intravenously over 60 min. Supine hemodynamic data were collected, and blood was sampled at the end of each infusion and at 120, 180, and 240 min thereafter. L-NAME increased mean arterial pressure, and the relative increase was greater in the tetraplegia group than in the control group. Heart rate was reduced after L-NAME administration in both groups. L-NAME decreased plasma norepinephrine in the control group but not in the group with tetraplegia. These findings suggest that reflexive sympathoinhibition normally buffers the pressor response to nitric oxide synthase inhibition, an effect that is not evident in individuals with tetraplegia as a result of decentralized sympathetic vasomotor control.     

Interleukin-7 deficiency in rheumatoid arthritis: consequences for therapy-induced lymphopenia

We previously demonstrated prolonged, profound CD4⁺ T-lymphopenia in rheumatoid arthritis (RA) patients following lymphocyte-depleting therapy. Poor reconstitution could result either from reduced de novo T-cell production through the thymus or from poor peripheral expansion of residual T-cells. Interleukin-7 (IL-7) is known to stimulate the thymus to produce new T-cells and to allow circulating mature T-cells to expand, thereby playing a critical role in T-cell homeostasis. In the present study we demonstrated reduced levels of circulating IL-7 in a cross-section of RA patients. IL-7 production by bone marrow stromal cell cultures was also compromised in RA. To investigate whether such an IL-7 deficiency could account for the prolonged lymphopenia observed in RA following therapeutic lymphodepletion, we compared RA patients and patients with solid cancers treated with high-dose chemotherapy and autologous progenitor cell rescue. Chemotherapy rendered all patients similarly lymphopenic, but this was sustained in RA patients at 12 months, as compared with the reconstitution that occurred in cancer patients by 3–4 months. Both cohorts produced naïve T-cells containing T-cell receptor excision circles. The main distinguishing feature between the groups was a failure to expand peripheral T-cells in RA, particularly memory cells during the first 3 months after treatment. Most importantly, there was no increase in serum IL-7 levels in RA, as compared with a fourfold rise in non-RA control individuals at the time of lymphopenia. Our data therefore suggest that RA patients are relatively IL-7 deficient and that this deficiency is likely to be an important contributing factor to poor early T-cell reconstitution in RA following therapeutic lymphodepletion. Furthermore, in RA patients with stable, well controlled disease, IL-7 levels were positively correlated with the T-cell receptor excision circle content of CD4⁺ T-cells, demonstrating a direct effect of IL-7 on thymic activity in this cohort.     

Microsatellite primers for Texas wild rice (<Emphasis Type="Italic">Zizania texana</Emphasis>), and a preliminary test of the impact of cryogenic storage on allele frequency at these loci

Seed collections in gene banks are useful for the preservation of wild germplasm, providing inexpensive insurance for species that survive in conventional cold storage (–18 °C). Seeds that cannot survive these conditions must be pretreated with cryoprotectants and stored at liquid nitrogen temperatures, which presents unique technical and methodological challenges. Implicit in this approach is the assumption that these added manipulations do not change the genetic diversity of the preserved collections. We used polymorphic microsatellite markers for an endangered aquatic grass, Texas wild rice (Zizania texana), to conduct a preliminary evaluation of the effects of cryogenic preservation of mature embryos on genetic diversity. Using several statistical approaches, we show that allele frequencies did not change in collections of seeds that underwent cryopreservation (cryoprotected) compared to those samples that was not exposed to cryopreservation (control). The retention of the allelic diversity at the five loci examined suggests that there were no significant changes in genetic diversity due to treatments and that these protocols may be appropriate for ex situ conservation of genetically diverse wild germplasm.     

Molecular Phylogeography and Evolutionary History of the Estuarine Copepod, Acartia Tonsa, on the Northwest Atlantic Coast

Coastal estuaries are useful model systems to study the ecological and evolutionary responses of organisms to highly variable, discontinuous habitats. For this study, the molecular population genetic diversity of the planktonic calanoid copepod Acartia tonsa (Dana, 1849) was described based on DNA sequence variation for a 183 base-pair region of the mitochondrial 16S rRNA gene. Samples of A. tonsa were collected from four estuaries on the Atlantic coast of the USA during 1993 and 1994, one estuary on the Gulf of Mexico coast in 1994, and one site on the Pacific coast of the USA in 1994. Dispersal of A. tonsa was shown to be restricted, with significant population genetic structuring between different estuaries. For all but the closely-adjacent MA and RI samples, frequencies of haplotypes and/or length polymorphisms within one haplotype (caused by insertion/deletion mutations) revealed highly significant genetic differentiation and geographic isolation. Mt16S haplotypes of A. tonsa from Atlantic and Gulf of Mexico estuaries were assorted among four deeply-diverged clades. Haplotypes within each clade differed by <2%, while differences among clades of 10% to 14% approached those between described Acartia species (e.g., 19% to 28% among A. clausi, A. hudsonica, and A. longiremis). Atlantic and Pacific coast samples identified as A. tonsa had no haplotypes in common and genetic differences between haplotypes ranged from 18% to 29%; phylogenetic analysis supported the separation of Pacific coast A. tonsa as a distinct species. We hypothesize that the observed patterns of molecular genetic diversity and structure of A. tonsa resulted from responses to historical climatic variation, including episodic range compression and displacement, and alteration of NW Atlantic coastal and estuarine environments.     

A gene-driven ENU-based approach to generating an allelic series in any gene

N-ethyl-N-nitrosourea (ENU) introduces mutations throughout the mouse genome at relatively high efficiency. Successful high-throughput phenotype screens have been reported and alternative screens using sequence-based approaches have been proposed. For the purpose of generating an allelic series in selected genes by a sequence-based approach, we have constructed an archive of over 4000 DNA samples from individual F₁ ENU-mutagenized mice paralleled by frozen sperm samples. Together with our previously reported archive, the total size now exceeds 6000 individuals. A gene-based screen of 27.4 Mbp of DNA, carried out using denaturing high-performance liquid chromatography (DHPLC), found a mutation rate of 1 in 1.01 Mbp of which 1 in 1.82 Mbp were potentially functional. Screening of whole or selected regions of genes on subsets of the archive has allowed us to identify 15 new alleles from 9 genes out of 15 tested. This is a powerful adjunct to conventional mutagenesis strategies and has the advantage of generating a variety of alleles with potentially different phenotypic outcomes that facilitate the investigation of gene function. It is now available to academic collaborators as a community resource.     

Efficacy of fiber bands impregnated with Beauveria brongniartii cultures against the Asian longhorned beetle, Anoplophora glabripennis (Coleoptera: Cerambycidae)

Use of 50 × 500 mm non-woven fiber bands impregnated with cultures of entomopathogenic fungi was investigated for control of Anoplophora glabripennis. Fungal bands produced as a commercial pest control product and obtained from industry contained Beauveria brongniartii NBL 851 while lab-produced bands contained B. brongniartii WU 20 or Metarhizium anisopliae VD 1. In the laboratory, adult longevity decreased when adult A. glabripennis were forced to walk for 5 s on bands impregnated with B. brongniartii NBL 851 and for 25 s on B. brongniartii WU 20 and M. anisopliae VD 1 bands. A field experiment was conducted over a 31-day period in Huaiyuan, Anhui, China, by attaching bands impregnated with B. brongniartii NBL 851 or WU 20 around the trunks of willows (Salix sp.) at two sites infested with A. glabripennis. Treatments were compared directly, by monitoring adult longevity, and indirectly, by counting oviposition scars and exit holes per tree to quantify relative oviposition per female. Adults collected from trees treated with B. brongniartii WU 20 died more quickly than adults from the trees treated with B. brongniartii NBL 851 or controls. At the site with higher A. glabripennis population densities, relative oviposition per female was significantly lower for both fungal treatments compared with the control treatment. Between fungal treatments, B. brongniartii NBL 851 had a 5 day earlier negative effect on oviposition per female than B. brongniartii WU 20.     

C6ORF66 is an assembly factor of mitochondrial complex I

Homozygosity mapping was performed in five patients from a consanguineous family who presented with infantile mitochondrial encephalomyopathy attributed to isolated NADH:ubiquinone oxidoreductase (complex I) deficiency. This resulted in the identification of a missense mutation in a conserved residue of the C6ORF66 gene, which encodes a 20.2 kDa mitochondrial protein. The mutation was also detected in a patient who presented with antenatal cardiomyopathy. In muscle of two patients, the levels of the C6ORF66 protein and of the fully assembled complex I were markedly reduced. Transfection of the patients' fibroblasts with wild-type C6ORF66 cDNA restored complex I activity. These data suggest that C6ORF66 is an assembly factor of complex I. Interestingly, the C6ORF66 gene product was previously shown to promote breast cancer cell invasiveness.     

No Evidence for a Difference in Neuropsychological Profile among Carriers and Noncarriers of the FMR1 Premutation in Adults under the Age of 50

The 5′ untranslated region of the fragile X mental retardation gene, FMR1, contains a polymorphic CGG repeat. Expansions of this repeat are associated with a spectrum of disorders. Full mutation alleles, repeats ≥ 200, are associated with fragile X syndrome. Premutation alleles, repeats of ~55–199, are associated with a tremor-ataxia syndrome most commonly in older males and primary ovarian insufficiency in females. However, the neuropsychological impact of carrying a premutation allele is presently unclear in younger adults. In this study, we analyzed neuropsychological scores for 138 males and 506 females ascertained from the general population and from families with a history of fragile X syndrome. Subjects were age 18–50 years and had varying repeat lengths. Neuropsychological scores were obtained from measures of general intelligence, memory, and executive functioning, including attention. Principal component analysis followed by varimax rotation was used to create independent factors for analysis. These factors were modeled for males and females separately via a general linear model that accounted for correlation among related subjects. All models were adjusted for potential confounders, including age at testing, ethnicity, and household income. Among males, no repeat length associations were detected for any factor. Among females, only a significant association with repeat length and self-report attention (p < 0.01) was detected, with premutation carriers self-reporting significantly more attention-related problems compared to noncarriers. No significant interactions between repeat length and age were detected. Overall, these results indicate the lack of a global neuropsychological impact of carrying a premutation allele among adults under the age of 50.