Determinants of peak muscle power: effects of age and physical conditioning

The relationships between absolute peak muscle power (W _peak), muscle cross sectional area (CSA_tot, i.e. the sum of both thigh and calf CSA) and muscle high energy phosphate concentration (adenosine 5-triphosphate [ATP] and phosphocreatine concentrations [PC]) were studied in 47 subjects classified into five groups: A, 10 sedentary (S) subjects aged 20–35 years; B, 9 S aged 35–50 years; C, 9 S aged more than 50 years; D, 13 children aged 8–13 years; and E, 6 athletes (top level volleyball players) aged 24 (SD 3) years. The W _peak was measured during a maximal vertical high jump off both feet on a force platform. The CSA_tot was measured anthropometrically. The [ATP] and [PC] were determined by ³¹Phosphorus nuclear magnetic resonance spectroscopy. The W _peak decreased with age, was 65% lower in D than in A, and 43% higher in E than in A. The CSA_tot did not vary with age, was 45% smaller in D than in A, and 15% greater in E than in A. The [ATP] and [PC] were essentially the same in all groups. The changes observed in W _peak were only partially accounted for by changes in CSA_tot. Therefore, in addition to the variables investigated, other factors appear to have been involved in the determination of W _peak with increasing age and training. An important role may be played by hormonal, particularly at puberty, and neural factors.     

Trends in Prevalence of Overweight and Obesity in Danish Infants,Children and Adolescents – Are We Still on a Plateau?

Background

After the worldwide steep increase in child and adolescent overweight and obesity during the last decades, there is now evidence of a levelling off in the prevalence in many countries in the Western world.

Aim

To examine whether there still is a plateau in the prevalence of overweight and obesity in Danish children and adolescents, or whether the prevalence is decreasing or rising again.

Methods

The trends in the prevalence rates were based on three data sets providing comparable repeated estimates: 1) the Danish Health Visitors Child Health Database (DHVCHD) with measurements on infant and childhood height and weight from 2002 to 2011 (n up to 39,984), 2) the Danish National Birth Cohort (DNBC) with maternal reports of measured infant and childhood height and weight from 1998 to 2010 (n up to 56,826) and 3) the Danish part of the Health Behaviour in School-aged Children survey (HBSC) with self-reported information on adolescent height and weight from the years 2002 to 2010 (n = 16,557). Overweight and obesity were categorized according to WHO growth standards. Trends were assessed by repeated point estimates and linear regression analyses providing regression coefficients for changes in per cent per year with 95% confidence intervals (CI).

Results

The prevalence rates of overweight and obesity for infants, children and adolescents showed a mixed pattern of decline, stability and increase (ranging from -1.10 through 0.29 per cent per year with CI’s from -3.10 through 2.37). Overall, there were no consistent statistically significant trends upwards or downwards, although some significant downward trends in childhood and adolescence were observed.

Conclusion

This study, based on data from 1998 through 2011, showed that the prevalence rates of overweight and obesity among Danish infants, children and adolescents were largely still on a plateau with tendencies for a decline among children and adolescents.     

Attempt to detect recombination between B-F and B-L genes within the chicken B complex by serological typing,in vitro MLR,and RFLP analyses

In search for recombinants within the chicken major histocompatibility B complex, 1155 animals from crosses between the congenic lines CB (B¹²) and CC (B⁴) were tested with alloantibodies and monoclonal antibodies for the B-F (class I), B-L (class II), and B-G (class IV) antigens and by mixed lymphocyte reaction. The absence of detectable recombination was confirmed by restriction fragment length polymorphism analysis with B-L and B-F probes. Together with previous reports, this indicates that the distance between the B-F and B-L loci is below 0.01 centimorgan.     

Evaluation of the fossil fish‐specific diversity in a chadian continental assemblage: Exploration of morphological continuous variation in Synodontis (Ostariophysi,Siluriformes)

In the fossil record, the quantification of continuous morphological variation has become a central issue when dealing with species identification and speciation. In this context, fossil taxa with living representatives hold great promise, because of the potential to characterise patterns of intraspecific morphological variation in extant species prior to any interpretation in the fossil record. The vast majority of catfish families fulfil this prerequisite, as most of them are represented by extant genera. However, although they constitute a major fish group in terms of distribution, and ecological and taxonomic diversity, the quantitative study of their past morphological variation has been neglected, as fossil specimens are generally identified based on the scarcest remains, that is, complete neurocrania that bear discrete characters. Consequently, a part of freshwater catfish history is unprospected and unknown. In this study, we explored the morphological continuous variation of the humeral plate shape in Synodontis catfishes using Elliptic Fourier Analysis (EFA), and compared extant members and fossil counterparts. We analysed 153 extant specimens of 11 Synodontis species present in the Chad basin, in addition to 23 fossil specimens from the Chadian fossiliferous area of Toros Menalla which is dated around 7 Ma. This highly speciose genus, which is one of the most diversified in Africa, exhibits a rich fossil record with several hundred remains mostly identified as Synodontis sp. The analysis of the outline of the humeral plate reveals that some living morphological types were already represented in the Chad Basin 7 My ago, and allows for the discovery of extinct species. Beside illuminating the complex Neogene evolutionary history of Synodontis, these results underline the interest in the ability of isolated remains to reconstruct a past dynamic history and to validate the relevance of EFA as a tool to explore specific diversity through time. J. Morphol. 277:1486–1496, 2016. © 2016 Wiley Periodicals, Inc.     

Evaluating the Ribosomal Internal Transcribed Spacer (ITS) as a Candidate Dinoflagellate Barcode Marker

Background

DNA barcoding offers an efficient way to determine species identification and to measure biodiversity. For dinoflagellates, an ancient alveolate group of about 2000 described extant species, DNA barcoding studies have revealed large amounts of unrecognized species diversity, most of which is not represented in culture collections. To date, two mitochondrial gene markers, Cytochrome Oxidase I (COI) and Cytochrome b oxidase (COB), have been used to assess DNA barcoding in dinoflagellates, and both failed to amplify all taxa and suffered from low resolution. Nevertheless, both genes yielded many examples of morphospecies showing cryptic speciation and morphologically distinct named species being genetically similar, highlighting the need for a common marker. For example, a large number of cultured Symbiodinium strains have neither taxonomic identification, nor a common measure of diversity that can be used to compare this genus to other dinoflagellates.

Methodology/Principal Findings

The purpose of this study was to evaluate the Internal Transcribed Spacer units 1 and 2 (ITS) of the rDNA operon, as a high resolution marker for distinguishing species dinoflagellates in culture. In our study, from 78 different species, the ITS barcode clearly differentiated species from genera and could identify 96% of strains to a known species or sub-genus grouping. 8.3% showed evidence of being cryptic species. A quarter of strains identified had no previous species identification. The greatest levels of hidden biodiversity came from Scrippsiella and the Pfiesteriaceae family, whilst Heterocapsa strains showed a high level of mismatch to their given species name.

Conclusions/Significance

The ITS marker was successful in confirming species, revealing hidden diversity in culture collections. This marker, however, may have limited use for environmental barcoding due to paralogues, the potential for unidentifiable chimaeras and priming across taxa. In these cases ITS would serve well in combination with other markers or for specific taxon studies.     

Effects of green fluorescent protein or beta-glucuronidase tagging on the accumulation and pathogenicity of a resistance-breaking Lettuce mosaic virus isolate in susceptible and resistant lettuce cultivars

The RNA genome of a resistance-breaking isolate of Lettuce mosaic virus (LMV-E) was engineered to express the jellyfish green fluorescent protein (GFP) or beta-glucuronidase (GUS) fused to the helper-component proteinase (HC-Pro) to study LMV invasion and spread in susceptible and resistant lettuce cultivars. Virus accumulation and movement were monitored by either histochemical GUS assays or detection of GFP fluorescence under UV light. The GFP- and GUS-tagged viruses spread systemically in the susceptible lettuce cultivars Trocadero and Vanguard, where they induced attenuated symptoms, compared with the wild-type virus. Accumulation of the GFP-tagged virus was reduced but less affected than in the case of the GUS-tagged virus. Systemic movement of both recombinant viruses was very severely affected in Vanguard 75, a lettuce cultivar nearly isogenic to Vanguard but carrying the resistance gene mo1(2). Accumulation of the recombinant viruses in systemically infected leaves was either undetectable (GUS-tag) or erratic, strongly delayed, and inhibited by as much as 90% (GFP-tag). As a consequence, and contrary to the parental virus, the recombinant viruses were not able to overcome the protection afforded by the mo1(2) gene. Taken together, these results indicate that GUS or GFP tagging of the HC-Pro of LMV has significant negative effects on the biology of the virus, abolishing its resistance-breaking properties and reducing its pathogenicity in susceptible cultivars.