Exercise training reduces skeletal muscle membrane arachidonate in the obese (fa/fa) Zucker rat

Compared with the lean(Fa/) genotype, obese(fa/fa) Zucker rats have arelative deficiency of muscle phospholipid arachidonate, and skeletalmuscle arachidonate in humans is positively correlated with insulinsensitivity. To assess the hypothesis that the positive effects ofexercise training on insulin sensitivity are mediated by increasedmuscle arachidonate, we randomized 20 lean and 20 obese weanling maleZucker rats to sedentary or treadmill exercise groups. After 9 wk,fasting serum, three skeletal muscles (white gastrocnemius, soleus, andextensor digitorum longus), and heart were obtained. Fasting insulinwas halved by exercise training in the obese rat. In whitegastrocnemius and extensor digitorum longus (fast-twitch muscles), butnot in soleus (a slow-twitch muscle) or heart, phospholipidarachidonate was lower in obese than in lean rats(P < 0.001). In all muscles,exercise in the obese rats reduced arachidonate(P < 0.03, by ANOVA contrast). Weconclude that improved insulin sensitivity with exercise in the obesegenotype is not mediated by increased muscle arachidonate and thatreduced muscle arachidonate in obese Zucker rats is unique tofast-twitch muscles.

     

You can't always get what you want: size assortative mating by mutual mate choice as a resolution of sexual conflict

Background  

Assortative mating patterns for mate quality traits like body size are often observed in nature. However, the underlying mechanisms that cause assortative mating patterns are less well known. Sexual selection is one important explanation for assortment, suggesting that i) one (usually the female) or both sexes could show preferences for mates of similar size or ii) mutual mate choice could resolve sexual conflict over quality traits into assortment. We tested these hypotheses experimentally in the socially monogamous cichlid fish Pelvicachromis taeniatus, in which mate choice is mutual.     

Molecular biodiversity of cassava begomoviruses in Tanzania: evolution of cassava geminiviruses in Africa and evidence for East Africa being a center of diversity of cassava geminiviruses

Cassava is infected by numerous geminiviruses in Africa and India that cause devastating losses to poor farmers. We here describe the molecular diversity of seven representative cassava mosaic geminiviruses (CMGs) infecting cassava from multiple locations in Tanzania. We report for the first time the presence of two isolates in East Africa: (EACMCV-[TZ1] and EACMCV-[TZ7]) of the species East African cassava mosaic Cameroon virus, originally described in West Africa. The complete nucleotide sequence of EACMCV-[TZ1] DNA-A and DNA-B components shared a high overall sequence identity to EACMCV-[CM] components (92% and 84%). The EACMCV-[TZ1] and -[TZ7] genomic components have recombinations in the same genome regions reported in EACMCV-[CM], but they also have additional recombinations in both components. Evidence from sequence analysis suggests that the two strains have the same ancient origin and are not recent introductions. EACMCV-[TZ1] occurred widely in the southern part of the country. Four other CMG isolates were identified: two were close to the EACMV-Kenya strain (named EACMV-[KE/TZT] and EACMV-[KE/TZM] with 96% sequence identity); one isolate, TZ10, had 98% homology to EACMV-UG2Svr and was named EACMV-UG2 [TZ10]; and finally one isolate was 95% identical to EACMV-[TZ] and named EACMV-[TZ/YV]. One isolate of African cassava mosaic virus with 97% sequence identity with other isolates of ACMV was named ACMV-[TZ]. It represents the first ACMV isolate from Tanzania to be sequenced. The molecular variability of CMGs was also evaluated using partial B component nucleotide sequences of 13 EACMV isolates from Tanzania. Using the sequences of all CMGs currently available, we have shown the presence of a number of putative recombination fragments that are more prominent in all components of EACMV than in ACMV. This new knowledge about the molecular CMG diversity in East Africa, and in Tanzania in particular, has led us to hypothesize about the probable importance of this part of Africa as a source of diversity and evolutionary change both during the early stages of the relationship between CMGs and cassava and in more recent times. The existence of multiple CMG isolates with high DNA genome diversity in Tanzania and the molecular forces behind this diversity pose a threat to cassava production throughout the African continent.     

The hemagglutinin envelope protein of canine distemper virus (CDV) confers cell tropism as illustrated by CDV and measles virus complementation analysis.

Measles virus (MV) and canine distemper virus (CDV) are morbilliviruses that cause acute illnesses and several persistent central nervous system infections in humans and in dogs, respectively. Characteristically, the cytopathic effect of these viruses is the formation of syncytia in permissive cells. In this study, a vaccinia virus expression system was used to express MV and CDV hemagglutinin (HA) and fusion (F) envelope proteins. We found that cotransfecting F and HA genes of MV or F and HA genes of CDV resulted in extensive syncytium formation in permissive cells while transfecting either F or HA alone did not. Similar experiments with heterologous pairs of proteins, CDV-F with MV-HA or MV-F with CDV-HA, caused significant cell fusion in both cases. These results indicate that in this expression system, cell fusion requires both F and HA; however, the functions of these proteins are interchangeable between the two types of morbilliviruses. Human-mouse somatic hybrids were used to determine the human chromosome conferring susceptibility to either MV and CDV. Of the 12 hybrids screened, none were sensitive to MV. Two of the hybrids containing human chromosome 19 formed syncytia following CDV infection. In addition, these two hybrids underwent cell fusion when cotransfected with CDV-F and CDV-HA (but not MV-F and MV-HA) glycoproteins by using the vaccinia virus expression system. To discover the viral component responsible for cell specificity, complementation experiments coexpressing CDV-HA with MV-F or CDV-F with MV-HA in the CDV-sensitive hybrids were performed. We found that syncytia were formed only in the presence of CDV-HA. These results support the idea that the HA protein is responsible for cell tropism. Furthermore, while the F protein is necessary for the fusion process, it is interchangeable with the F protein from other morbilliviruses.     

Gene by smoking interaction: evidence for effects on low-density lipoprotein size and plasma levels of triglyceride and high-density lipoprotein cholesterol

We seek to determine whether significant gene x smoking interaction effects exist on plasma triglyceride (TG) levels, HDL cholesterol (HDL-C) level, and median LDL particle diameter (LDL-MPD) in Mexican American families enrolled in the San Antonio Family Heart Study. The sample consisted of 1,392 individuals distributed in 42 extended pedigrees, ranging in age from 16 years to 92 years. Separate quantitative genetic analyses were carried out for TG and HDL-C level and LDL-MPD using a maximum-likelihood-based variance decomposition approach while simultaneously adjusting for age and sex. Initial heritability estimates demonstrated significant (p < 0.001) additive genetic contributions to all three traits (h2 range 0.50 - 0.54). To test for a gene x smoking interaction, we included in the model additional smoking-status-specific variance terms and a genetic correlation term between smokers and nonsmokers. Comparisons of nested models revealed significant evidence (p < 0.01) for a gene X smoking interaction effect on TG level and LDL-MPD and possible evidence for an effect on HDL-C level. These results indicate that the gene or suite of genes regulating each of these phenotypes is likely the same in smokers and non-smokers but that smoking may alter the expression of genes, particularly those influencing TG level and LDL-MPD.     

Severity of Mitral Valve Degeneration Is Associated with Chromosome 15 Loci in Whippet Dogs

Mitral valve degeneration (MVD) is the most common form of heart disease in dogs, frequently leading to left-sided congestive heart failure and cardiac mortality. Although breed-specific disease characteristics and overrepresentation point towards a genetic origin for MVD, a causative mutation and complete molecular pathogenesis are unknown. Whippet dogs are overrepresented in incidence of MVD, suggesting an inherited component in this breed. Expressivity of this condition is variable with some dogs showing evidence of more severe disease at earlier ages than other dogs. This phenomenon makes a traditional case versus control genetic study prone to phenotyping error. This study sought to avoid these common pitfalls by identifying genetic loci associated with severity of MVD in Whippets through a genome-wide association study (GWAS). 138 Whippet dogs were characterized for MVD by echocardiographic examination and a novel disease severity score was developed and adjusted for age in each subject. Single nucleotide polymorphism (SNP) genotype data (170k Illumina CanineHD SnpChip) was obtained for DNA isolated from blood of each study subject. Continuous variable genome wide association was performed after correction for population stratification by efficient mixed model association expedited (EMMAX) in 130 dogs. A genome wide significant association was identified on chromosome 15 (peak locus 57,770,326; P_adj = 0.049) and secondary loci of suggestive association were identified on chromosome 2 (peak locus 37,628,875; P_adj = 0.079). Positional candidate genes were identified within the primary and secondary loci including follistatin-related protein 5 precursor (FSTL5) and Rho GTPase-activating protein 26 (ARHGAP26). These results support the hypothesis that severity of MVD in whippets has a genetic basis and warrants further study by either candidate gene sequencing or next-generation techniques.     

Mutations in the Drosophila Pushover Gene Confer Increased Neuronal Excitability and Spontaneous Synaptic Vesicle Fusion

We describe the identification of a gene called pushover (push), which affects both behavior and synaptic transmission at the neuromuscular junction. Adults carrying either of two mutations in push exhibit sluggishness, uncoordination, a defective escape response, and male sterility. Larvae defective in push exhibit increased release of transmitter at the neuromuscular junction. In particular, the frequency of spontaneous transmitter release and the amount of transmitter release evoked by nerve stimulation are each increased two- to threefold in push mutants at the lowest external [Ca(2+)] tested (0.15 mM). Furthermore, these mutants are more sensitive than wild type to application of the potassium channel-blocking drug quinidine: following qunidine application, push mutants, but not wild-type, display repetitive firing of the motor axon, leading to repetitive muscle postsynaptic potentials. The push gene thus might affect both neuronal excitability and the transmitter release process. Complementation tests and recombinational mapping suggest that the push mutations are allelic to a previously identified P-element-induced mutation, which also causes behavioral abnormalities and male sterility.     

Sexual behaviour and paternity in three captive groups of rhesus monkeys (Macaca mulatta)

Each offspring born into three captive groups of rhesus monkeys (Macaca mulatta) during the spring of 1981 was assigned (1) a most probable behavioural father and (2) a subset of all possible behavioural fathers, on the basis of intensive observations of sexual activity during the 1980 fall breeding season. These predictions were then compared with true paternity determined by electrophoretic and serological analyses of polymorphic blood proteins of mothers, infants, and all adult and subadult males. Coincidence between the assignments of paternity based upon behavioural and biochemical data occurred no more frequently than chance would allow. Furthermore, there were no significant relationships between biochemical and behavioural rankings of overall reproductive success. It was concluded that conventional estimates of sexual activity during the breeding season are not a reliable indicator of true paternity and relative reproductive success in rhesus macaques.