RNA trafficking and stabilization elements associate with multiple brain proteins

Two of the best understood somatic cell mRNA cytoplasmic trafficking elements are those governing localization of beta-actin and myelin basic protein mRNAs. These cis-acting elements bind the trans-acting factors fibroblast ZBP-1 and hnRNP A2, respectively. It is not known whether these elements fulfil other roles in mRNA metabolism. To address this question we have used Edman sequencing and western blotting to identify six rat brain proteins that bind the beta-actin element (zipcode). All are known RNA-binding proteins and differ from ZBP-1. Comparison with proteins that bind the hnRNP A2 and AU-rich response elements, A2RE/A2RE11 and AURE, showed that AURE and zipcode bind a similar set of proteins that does not overlap with those that bind A2RE11. The zipcode-binding protein, KSRP, and hnRNP A2 were selected for further study and were shown by confocal immunolluorescence microscopy to have similar distributions in the central nervous system, but they were found in largely separate locations in cell nuclei. In the cytoplasm of cultured oligodendrocytes they were segregated into separate populations of cytoplasmic granules. We conclude that not only may there be families of trans-acting factors for the same cis-acting element, which are presumably required at different stages of mRNA processing and metabolism, but independent factors may also target different and multiple RNAs in the same cell.

Heterogeneous nuclear ribonucleoprotein A3, a novel RNA trafficking response element-binding protein

The cis-acting response element, A2RE, which is sufficient for cytoplasmic mRNA trafficking in oligodendrocytes, binds a small group of rat brain proteins. Predominant among these is heterogeneous nuclear ribonucleoprotein (hnRNP) A2, a trans-acting factor for cytoplasmic trafficking of RNAs bearing A2RE-like sequences. We have now identified the other A2RE-binding proteins as hnRNP A1/A1(B), hnRNP B1, and four isoforms of hnRNP A3. The rat and human hnRNP A3 cDNAs have been sequenced, revealing the existence of alternatively spliced mRNAs. In Western blotting, 38-, 39-, 41 -, and 41.5-kDa components were all recognized by antibodies against a peptide in the glycine-rich region of hnRNP A3, but only the 41- and 41.5-kDa bands bound antibodies to a 15-residue N-terminal peptide encoded by an alternatively spliced part of exon 1. The identities of these four proteins were verified by Edman sequencing and mass spectral analysis of tryptic fragments generated from electrophoretically separated bands. Sequence-specific binding of bacterially expressed hnRNP A3 to A2RE has been demonstrated by biosensor and UV cross-linking electrophoretic mobility shift assays. Mutational analysis and confocal microscopy data support the hypothesis that the hnRNP A3 isoforms have a role in cytoplasmic trafficking of RNA.

Body mass index-related human adipocyte agouti expression is sex-specific but not depot-specific

Objective: To determine if human adipocyte agouti signal protein (ASIP) mRNA expression is associated with obesity and is gender and/or depot specific. Research Methods and Procedures: Subjects included 8 men (64 +/- 3 years) and 14 women (56 +/- 15 years) undergoing elective abdominal surgery. ASIP mRNA levels in isolated omental and subcutaneous abdominal adipocytes were measured by quantitative reverse transcription polymerase chain reaction. Results: No significant depot difference was observed between genders; ASIP mRNA levels of omental and subcutaneous abdominal adipocytes were pooled for this analysis. BMI and ASIP gene expression were negatively correlated in men (p = -0.70; p < 0.05), whereas a positive relationship was observed in women (p = 0.48; p < 0.05). No significant difference was observed in age, body weight, body mass index (BMI), and waist circumference between groups. Hip circumference was significantly higher in women than in men (p < 0.05). Also, no significant difference in ASIP mRNA expression was observed between men and women, regardless of the fat depot. Discussion: These results show that men and women of similar age and BMI present similar ASIP mRNA levels in omental and subcutaneous abdominal adipocytes. However, a sexual dimorphism exists in the relationship between ASIP expression and BMI. If ASIP is involved in appetite regulation or energy homeostasis in humans, this observation may contribute to the recognized differences in these parameters between men and women.

Minor genes are involved in ascochyta blight resistance in lentils

In addition to a gene with major effect, minor genes were found to contribute to the genetic regulation of foliar resistance to Ascochyta blight in two crosses between two resistant and one susceptible lentil cultivars (lines). This was established by comparing inbred lines with and without the major resistance gene. The effects of minor genes were not large enough to change the phenotypic performance determined by its major gene qualitatively (from resistant to susceptible, or vice versa) based on the measurement scale used. However, they did substantially and significantly modify the resistance level. The major gene for foliar resistance was linked to the gene(s) for seed infection rate and/or had a positive pleiotrophic effect on seed infection rate. Similarly, the major gene for foliar resistance was linked to the gene(s) for seed yield/plant in disease free environments and/or had negative pleiotrophic effects on yield/plant. Selection for resistance and yield among inbreds with the same major resistance gene may be necessary to enhance the resistance level, and to reduce the negative effect on yield of the major resistance gene.

Peanut resistance to Sclerotinia minor and S-sclerotiorum

The fungi Sclerotinia minor and S. sclerotiorum are the causal agents of two similar diseases of peanut (Arachis hypogaea L.). Both diseases cause significant losses in the Australian peanut industry. Development of cultivars with resistance to Sclerotinia will be an important component of integrated control. The aims of this project are to generate information that will assist in breeding for Sclerotinia resistance in peanut: to identify Sclerotinia-resistant peanut germplasm, to understand the inheritance and estimate heritability of resistance, and to test the effectiveness of identified sources of resistance against both S. minor and S. sclerotiorum. This study has clearly established that material that shows resistance to S. minor in the USA is resistant to S. minor and likely to be resistant to S. sclerotiorum in Australia. The high level of resistance to both S. minor and S. sclerotiorum in germplasm from Texas, particularly TxAG-4, was confirmed. VA 93B showed good resistance in the field, which is primarily due to the open bush type rather than physiological resistance. Physiological resistance to S. minor was also identified in a cultivar and a landrace from Indonesia and a rust-resistant line from Queensland. All germplasm found to have high physiological resistance to S. minor belonged to the Spanish type. Inheritance of physiological resistance to S. minor was studied using a Generation Means Analysis (GMA) of the cross TxAG-4/VA 93B and its reciprocal. The broad-sense heritability of physiological resistance on a single plant basis was estimated at 47%, much higher than earlier estimates obtained in field studies. The average gene action of Sclerotinia resistance genes from TxAG-4 was found to be additive. No dominance effects were detected in the GMA. A small but significant reciprocal effect between TxAG-4 and VA 93B indicated that VA 93B passed on some physiological resistance maternally. An experiment was conducted to confirm the value of resistance against both S. minor and S. sclerotiorum. TxAG-4 was found to have physiological resistance to both S. minor and S. sclerotiorum. This resistance was expressed against both Sclerotinia species by progeny that were selected for resistance to S. minor. On the basis of the information obtained, the comparative advantages of 3 strategies for Sclerotinia-resistant cultivar development are discussed: (1) introduction of germplasm; (2) recurrent backcrossing with screening and crossing in the BCnF1 generation; and (3) pedigree selection. At present, introduction and backcrossing are recommended as the preferred strategies.

Sex allocation in the sexually monomorphic fairy martin

Offspring sex ratios were examined at the population and family level in the sexually monomorphic, socially monogamous fairy martin Petrochelidon ariel at five colony sites over a 4-year period (1993 1996). The sex of 465 nestlings from 169 broods % as determined using sex-specific PCR at the CHD locus. In accordance with predicted sex allocation patterns, population sex ratios at hatching and fledging did not differ from parity in an), year and the variance in brood sex ratios did not deviate from the binomial distribution, Further, brood sex ratio did not vary with hatching date during the season, brood number, brood size or colony size, The sex ratio or broods with extra-pair young did not differ from those without, while the sex ratio of broods fathered by males that gained extra-pair fertilizations did not differ from broods fathered by other males. Extra-pair chicks were as likely to be male as female. Neither the total number of feeding visits to the brood nor the relative feeding contribution by the sexes varied significantly with brood sex ratio. Brood sex ratios were also unrelated to paternal size, condition and breeding experience or maternal condition and breeding experience, However, contrary to our prediction, brood sex ratio was negatively correlated with maternal size. Generally, these results were consistent with our expectations that brood sex ratios would not vary with environmental factors or parental characteristics, and would not influence the level of parental provisioning. However, the finding that females with longer tarsi produced an excess of daughters is difficult to reconcile with our current understanding or fairy martin life history and breeding ecology.

Carpogenic germination of Sclerotinia minor and potential distribution in Australia

This study confirms that Australian isolates of Sclerotinia minor can produce fertile apothecia and further demonstrates that ascospores collected from these apothecia are pathogenic to sunflower (Helianthus annuus). Sunflower is a known host of the related fungus Sclerotinia sclerotiorum and is grown in some regions where S. minor is known to occur. Head rot symptoms were produced following inoculation with S. minor ascospores. Predictive modeling using CLIMEX software suggested that conditions suitable for carpogenic germination of S. minor probably occur in Australia particularly in southern regions. Carpogenic germination is probably a rare event in northern regions and, if it does occur, probably does not coincide with anthesis in sunflower crops, therefore allowing disease escape.

The influence of increased line-fishing mortality on the sex ratio and age of sex reversal of the venus tusk fish

The age of sex reversal of the venus tusk fish Choerodon venustus, caught by line fishing at various locations on the southern Great Barrier Reef, indicated that C. venustus is capable of modifying its life cycle in response to increased mortality. The evidence suggests Masthead Reef fish, which experience the highest mortality, underwent sex reversal at a smaller size and younger age than at the other sites. The largest female fish, sexually transitional fish and males were smaller at Masthead Reef than at the Swains Reefs or One Tree Reef at Masthead Reef. There was also considerable overlap in the size of males and females within the exploited populations indicating that sex reversal is not initiated at a particular length but may have a social cause. The sex ratio of fish was essentially the same for fish fully susceptible to line fishing in the Swains and Masthead samples. Circumstantial evidence suggested that the absence of large males in a population may initiate sex reversal, indicating the maintenance of a constant sex ratio may have a social basis. (C) 2002 The Fisheries Society of the British Isles.

Lateralization of speech production using verbal/manual dual tasks: meta-analysis of sex differences and practice effects

The present paper reviews the findings of 30 years of verbal/manual dual task studies, the method most commonly used to assess lateralization of speech production in non-clinical samples. Meta-analysis of 64 results revealed that both the type of manual task used and the nature of practice that is given influence the size of the laterality effect. A meta-analysis of 36 results examining the effect size of sex differences in estimate,, of lateralization of speech production indicated that males appear to show, slightly larger laterality effects than females. (C) 2002 Elsevier Science Ltd. All rights reserved.

Patterning of the vertebrate ventral spinal cord

We review investigations that have lead to a model of how the ventral spinal cord of higher vertebrate embryos is patterned during development. Central to this model is the secreted morphogen protein, Sonic hedgehog. There is now considerable evidence that this molecule acts in a concentration-dependent manner to direct the development of the spinal cord. Recent studies have suggested that two classes of homeodomain proteins are induced by threshold concentrations of Sonic hedgehog. Reciprocal inhibition between the two classes acts to convert the continuous gradient of Sonic hedgehog into defined domains of transcription factor expression. However, a number of aspects of ventral spinal cord patterning remain to be elucidated. Some issues currently under investigation involve temporal aspects of Shh-signalling, the role of other signals in ventral patterning and the characterisation of ventral interneurons. In this review, we discuss the current state of knowledge of these issues and present some preliminary studies aimed at furthering understanding of these processes in spinal cord patterning.

Sex differences in heritability of BMI: A comparative study of results from twin studies in eight countries

Body mass index (BMI), a simple anthropometric measure, is the most frequently used measure of adiposity and has been instrumental in documenting the worldwide increase in the prevalence of obesity witnessed during the last decades. Although this increase in overweight and obesity is thought to be mainly due to environmental changes, i.e., sedentary lifestyles and high caloric diets, consistent evidence from twin studies demonstrates high heritability and the importance of genetic differences for normal variation in BMI. We analysed self-reported data on BMI from approximately 37,000 complete twin pairs (including opposite sex pairs) aged 20-29 and 30-39 from eight different twin registries participating in the GenomEUtwin project. Quantitative genetic analyses were conducted and sex differences were explored. Variation in BMI was greater for women than for men, and in both sexes was primarily explained by additive genetic variance in all countries. Sex differences in the variance components were consistently significant. Results from analyses of opposite sex pairs also showed evidence of sex-specific genetic effects suggesting there may be some differences between men and women in the genetic factors that influence variation in BMI. These results encourage the continued search for genes of importance to the body composition and the development of obesity. Furthermore, they suggest that strategies to identify predisposing genes may benefit from taking into account potential sex specific effects.