Tick neurobiology: recent advances and the post-genomic era

Increasing worldwide resistance to acaricides necessitates greater research on the identification of potential acaricide targets in ticks to aid in the control of these serious pests of medical and veterinary importance. Historically, and most likely in the future, acaricide targets are largely of neural origin, but our knowledge of tick neurobiology is surprisingly limited. The tick central nervous system is a fused nerve mass, termed the synganglion. Tick synganglion material is relatively easily accessible to most researchers and employing modern amplification methods of complementary-DNA construction is readily amenable for gene cloning investigations. The various tick neurotransmitter systems are described with emphasis on our current knowledge of both existing and potential acaricide targets at the molecular level. We describe the impact of mass gene sequencing (expressed sequence tag and genome projects), advances in bioinformatics and RNA-interference on target identification and validation.     

Androgen dependent regulation of protein kinase A subunits in prostate cancer cells

Neuroendocrine (NE) cells may play a role in prostate cancer progression. Both androgen deprivation and cAMP are well known inducers of NE differentiation (NED) in the prostate. Gene-expression profiling of LNCaP cells, incubated in androgen stripped medium, showed that the Cbeta isoform of PKA is up-regulated during NE differentiation. Furthermore, by using semi-quantitative RT-PCR and immunoblotting analysis, we observed that the Cbeta splice variants are differentially regulated during this process. Whereas the Cbeta2 splice variant is down-regulated in growth arrested LNCaP cells, the Cbeta1, Cbeta3 and Cbeta4 variants, as well as the RIIbeta subunit of PKA, are induced in NE-like LNCaP cells. The opposite effect of Cbeta expression could be mimicked by androgen stimulation, implying the Cbeta gene of PKA as a putative new target gene for the androgen receptor in prostate cancer. Moreover, to investigate expression of PKA subunits during prostate cancer progression, we did immunoblotting of several prostatic cell lines and normal and tumor tissue from prostate cancer patients. Interestingly, multiple Cbeta subunits were also observed in human prostate specimens, and the Cbeta2 variant was up-regulated in tumor cells. In conclusion, it seems that the Cbeta isoforms play different roles in proliferation and differentiation and could therefore be potential markers for prostate cancer progression.     

Stress and domestication traits increase the relative fitness of crop-wild hybrids in sunflower

After a decade of transgenic crop production, the dynamics of gene introgression into wild relatives remain unclear. Taking an ecological genetics approach to investigating fitness in crop-wild hybrid zones, we uncovered both conditions and characteristics that may promote introgression. We compared diverse crop-wild hybrid genotypes relative to wild Helianthus annuus under one benign and three stressful agricultural environments. Whereas relative fitness of crop-wild hybrids averaged 0.25 under benign conditions, with herbicide application or competition it reached 0.45 and was more variable. In some instances, hybrid fitness matched wild fitness (approximately 1). Thus, wild populations under agronomic stress may be more susceptible to introgression. Although 'domestication' traits are typically considered unlikely to persist in wild populations, we found some (e.g. rapid growth and early flowering) that may enhance hybrid fitness, especially in stressful environments. Rigorous assessment of how particular genotypes, phenotypes, and environments affect introgression will improve risk assessment for transgenic crops.     

Pakistanis living in Oslo have lower serum 1,25-dihydroxyvitamin D levels but higher serum ionized calcium levels compared with ethnic Norwegians. The Oslo Health Study

Background

Clinical determination of mid-parental height is an important part of the assessment of a child's growth, however our clinical impression has been that parents cannot be relied upon to accurately report their own heights. Therefore, we conducted this study to assess the accuracy of parental height self-reporting and its effect on calculated mid-parental target height for children presenting to a pediatric endocrinology office.

Methods

All parents bringing their children for an initial evaluation to a pediatric endocrinology clinic over a period of nine months were questioned and then measured by a pediatric endocrinologist. Parents were blinded to the study. Mid-parental target heights, based on reported and actual height were compared.

Results

There were 241 families: 98 fathers and 217 mothers in our study. Mean measured paternal height was 173.2 cm, self reported 174.9 cm (p < 0.0001), partner reported 177 cm (p = 0.0004). Only 50% of fathers and 58% of mothers reported their height within ± 2 cm of their measured height, while 15% of fathers and 12% of mothers were inaccurate by more than 4 cm. Mean measured maternal height was 160.6 cm, self-reported 161.1 cm (NS), partner reported 161.7 cm (NS). Inaccuracy of height self-report had a small but significant effect on the mean MPTH (0.4 cm, p = 0.045). Analysis showed that only 70% of MPTH calculated by reported heights fell within ± 2 cm of MPTH calculated using measured heights, 24% being in ± 2–4 cm range, and 6% were inaccurate by more than 4 cm.

Conclusion

There is a significant difference in paternal measured versus reported heights with an overall trend for fathers to overestimate their own height. A large subset of parents makes a substantial error in their height self-report, which leads to erroneous MPTH. Inaccuracy is even greater when one parent reports the other parent's height. When a child's growth is in question, measured rather than reported parental heights should be obtained.     

A critical function for the actin cytoskeleton in targeted exocytosis of prefusion vesicles during myoblast fusion

Myoblast fusion is an essential step during muscle differentiation. Previous studies in Drosophila have revealed a signaling pathway that relays the fusion signal from the plasma membrane to the actin cytoskeleton. However, the function for the actin cytoskeleton in myoblast fusion remains unclear. Here we describe the characterization of solitary (sltr), a component of the myoblast fusion signaling cascade. sltr encodes the Drosophila ortholog of the mammalian WASP-interacting protein. Sltr is recruited to sites of fusion by the fusion-competent cell-specific receptor Sns and acts as a positive regulator for actin polymerization at these sites. Electron microscopy analysis suggests that formation of F-actin-enriched foci at sites of fusion is involved in the proper targeting and coating of prefusion vesicles. These studies reveal a surprising cell-type specificity of Sltr-mediated actin polymerization in myoblast fusion, and demonstrate that targeted exocytosis of prefusion vesicles is a critical step prior to plasma membrane fusion.     

Proteome changes in bovine longissimus thoracis muscle during the early postmortem storage period

Postmortem changes in protein composition up to 24 h in bovine longissimus thoracis muscle were investigated by two-dimensional gel electrophoresis and MALDI-TOF MS/MS. A total of 47 spots were significantly changed the first 24 h postmortem. The 39 identified proteins can be divided into five groups: metabolic enzymes, defense and stress proteins, structural proteins, proteolytic enzymes, and unclassified proteins. The identified metabolic enzymes are all associated with ATP-generating pathways, either the glycolytic pathway or energy metabolism. In addition, several defense and stress proteins were changed in abundance in this study. These findings contribute to a better understanding of the biochemical processes during postmortem storage of meat.     

Effects of Norspermidine and Spermidine on Biofilm Formation by Potentially Pathogenic Escherichia coli and Salmonella enterica Wild-Type Strains

Polyamines are present in all living cells. In bacteria, polyamines are involved in a variety of functions, including biofilm formation, thus indicating that polyamines may have potential in the control of unwanted biofilm. In the present study, the effects of the polyamines norspermidine and spermidine on biofilms of 10 potentially pathogenic wild-type strains of Escherichia coli serotype O103:H2, Salmonella enterica subsp. enterica serovar Typhimurium, and S. enterica serovar Agona were investigated. We found that exogenously supplied norspermidine and spermidine did not mediate disassembly of preformed biofilm of any of the E. coli and S. enterica strains. However, the polyamines did affect biofilm production. Interestingly, the two species reacted differently to the polyamines. Both polyamines reduced the amount of biofilm formed by E. coli but tended to increase biofilm formation by S. enterica. Whether the effects observed were due to the polyamines specifically targeting biofilm formation, being toxic for the cells, or maybe a combination of the two, is not known. However, there were no indications that the effect was mediated through binding to exopolysaccharides, as earlier suggested for E. coli. Our results indicate that norspermidine and spermidine do not have potential as inhibitors of S. enterica biofilm. Furthermore, we found that the commercial polyamines used contributed to the higher pH of the test medium. Failure to acknowledge and control this important phenomenon may lead to misinterpretation of the results.     

Rotifers as experimental tools for investigating aging

Comparative biogerontology has much to contribute to the study of aging. A broad range of aging rates have evolved to meet environmental challenges, and understanding these adaptations can produce valuable insights into aging. The supra Phylum Lophotrochozoa is particularly understudied and has several groups that have intriguing patterns of aging. Members of the Lophotrochozoan phylum Rotifera are particularly useful for aging studies because cohort life tables can be conducted with them easily, and biochemical and genomic tools are available for examining aging mechanisms. This paper reviews a variety of caloric restriction (CR) regimens, small molecule inhibitors, and dietary supplements that extend rotifer lifespan, as well as important interactions between CR and genotype, antioxidant supplements, and TOR and jun-N-terminal kinase (JNK) pathways, and the use of RNAi to identify key genes involved in modulating the aging response. Examples of how rapamycin and JNK inhibitor exposure keeps mortality rates low during the reproductive phase of the life cycle are presented, and the ease of conducting life table experiments to screen natural products from red algae for life extending effects is illustrated. Finally, experimental evolution to produce longer-lived rotifer individuals is demonstrated, and future directions to determine the genetic basis of aging are discussed.     

Climate impacts on transocean dispersal and habitat in gray whales from the Pleistocene to 2100

Arctic animals face dramatic habitat alteration due to ongoing climate change. Understanding how such species have responded to past glacial cycles can help us forecast their response to today's changing climate. Gray whales are among those marine species likely to be strongly affected by Arctic climate change, but a thorough analysis of past climate impacts on this species has been complicated by lack of information about an extinct population in the Atlantic. While little is known about the history of Atlantic gray whales or their relationship to the extant Pacific population, the extirpation of the Atlantic population during historical times has been attributed to whaling. We used a combination of ancient and modern DNA, radiocarbon dating and predictive habitat modelling to better understand the distribution of gray whales during the Pleistocene and Holocene. Our results reveal that dispersal between the Pacific and Atlantic was climate dependent and occurred both during the Pleistocene prior to the last glacial period and the early Holocene immediately following the opening of the Bering Strait. Genetic diversity in the Atlantic declined over an extended interval that predates the period of intensive commercial whaling, indicating this decline may have been precipitated by Holocene climate or other ecological causes. These first genetic data for Atlantic gray whales, particularly when combined with predictive habitat models for the year 2100, suggest that two recent sightings of gray whales in the Atlantic may represent the beginning of the expansion of this species' habitat beyond its currently realized range.