The phylogeny of the ant tribe Formicini (Hymenoptera: Formicidae) with the description of a new genus

Abstract. The holarctic ant tribe Formicini is revised, the new genus Bajcaridris described, and possible phylogenetic relationships are discussed. The subgenus Iberoformica is synonymized with Formica. A synopsis, diagnosis and keys to the genera are provided.     

Insect mitochondrial genomics: the complete mitochondrial genome sequence of the meadow spittlebug Philaenus spumarius (Hemiptera: Auchenorrhyncha: Cercopoidae).

We present the complete mitochondrial genome sequence of the meadow spittlebug Philaenus spumarius (Auchenorrhyncha: Cercopoidae). This contribution represents the second mitochondrial genome from the Hemiptera and the second of the three hemipteran suborders sampled. The genome is a circular molecule of 16 324 bp with a total A+T content of 77.0% and 76.7% for coding regions only. The gene content, order, and structure are consistent with the Drosophila yakuba genome structure (Clary and Wolstenholme 1985) and the hypothesized ancestral arthropod genome arrangement (Crease 1999). Nucleotide composition and codon usage are near the means observed in other insect mitochondria sequenced to date but have a higher A+T richness compared with the other hemipteran example, the kissing bug Triatoma dimidiata (Dotson and Beard. 2001. Insect Mol. Biol. 10: 205-215). The major noncoding region (the A+T rich region or putative control region) between the small ribosomal subunit and the tRNAIle gene includes two extensive repeat regions. The first repeat region includes 19 tandem repeats of a 46-bp sequence, whereas the second contains a longer sequence (146 bp) tandemly repeated four times.     

Mitochondrial genome sequences of representatives of three families of scorpionflies (Order Mecoptera) and evolution in a major duplication of coding sequence

The complete mitochondrial DNA sequences of a hangingfly, Bittacus pilicornis (Mecoptera: Bittacidae), a snow scorpion fly, Boreus elegans (Mecoptera: Boreidae), and a nearly complete sequence from another scorpionfly species, Microchorista philpotti (Mecoptera: Nannochoristidae) were determined. The coding sequence of all three genomes includes the 37 genes normally found in insect mtDNAs, in the same gene order as first described in Drosophila. In addition to the standard set of genes, the Microchorista sequence includes a large duplication of the coding region. The duplication is at least 4?kb (and may be much larger) and includes the remnants of three protein-coding genes and seven tRNA genes. The duplication evidently arose as a single event, and the duplicated region can be aligned in its entirety with the corresponding region of the functional genome. Although most of the genes contain defects that render them nonfunctional, analysis shows that the protein-coding genes in the duplicated region evolved for a considerable period under constraints expected of functional protein-coding genes. It is evident, therefore, that for a period two copies of some of the mitochondrial genes were functional in this species, including genes coding for proteins.     

Sex differences in the rate of fatigue development and recovery

Background

Many musculoskeltal injuries in the workplace have been attributed to the repetitive loading of muscle and soft tissues. It is not disputed that muscular fatigue is a risk factor for musculoskeltal injury, however the disparity between gender with respect to muscular fatigability and rate of recovery is not well understood. Current health and safety guidelines do not account for sex differences in fatiguability and may be predisposing one gender to greater risk. The purpose of this study was to quantify the sex differences in fatigue development and recovery rate of lower and upper body musculature after repeated bouts of sustained isometric contractions.

Methods

Twenty-seven healthy males (n = 12) and females (n = 15) underwent bilateral localized fatigue of either the knee extensors (male: n = 8; female: n = 8), elbow flexors (male: n = 8; female: n = 10), or both muscle groups. The fatigue protocol consisted of ten 30-second sub-maximal isometric contractions. The changes in maximum voluntary contraction (MVC), electrically evoked twitches, and motor unit activation (MUA) were assessed along with the ability to control the sustained contractions (SLP) during the fatigue protocol using a mixed four-factor repeated measures ANOVA (gender × side × muscle × time) design with significance set at p < 0.05.

Results

There was a significant loss of MVC, MUA, and evoked twitch amplitude from pre- to post-fatigue in both the arms and legs. Males had greater relative loss of isometric force, a higher rate of fatigue development, and were less capable of maintaining the fatiguing contractions in the legs when compared to the females.

Conclusion

The nature of the induced fatigue was a combination of central and peripheral fatigue that did not fully recover over a 45-minute period. The results appear to reflect sex differences that are peripheral, and partially support the muscle mass hypothesis for explaining differences in muscular fatigue.

     

Mitochondrial DNA Length Variation and Heteroplasmy in Populations of White Sturgeon (Acipenser Transmontanus)

Southern blot analysis was used to quantify the extent of mtDNA D-loop length variation in two populations of white sturgeon, Acipenser transmontanus. Over 42% of individuals were heteroplasmic for up to six different mtDNA length variants attributable to varying copy numbers of an 82-bp repeat sequence. Chi-square analyses revealed that the frequencies of length genotypes and the incidence of heteroplasmy were significantly different between Fraser and Columbia River sturgeon populations but not between restriction site haplotypes. Heteroplasmic fish have, on average, higher copy number than homoplasmic fish. Forty-five of 101 homoplasmic individuals carry only a single copy of the repeat, while none of the 73 heteroplasmic fish has the single repeat as the predominant variant. On the basis of differences in frequency distributions of copy number within and between fish, we suggest that (1) heteroplasmy is maintained by high recurrent mutation of multiple copy genomes, favoring increased copy number and (2) the mutation pressure toward higher copy number heteroplasmy is partially offset by selection to reduced genome size and segregation to the homoplasmic condition.     

Evolution of the mitochondrial cytochrome oxidase II gene among 10 orders of insects.

We examine the complete nucleotide sequences of the mitochondrial cytochrome oxidase II gene of 13 species of insects, representing 10 orders. The genes range from 673 to 690 bp in length, encoding 226 to 229 amino acids. Several insertion or deletion events, each involving one or two codons, can be observed. The 3' end of the gene is extremely variable in both length and sequence, making alignment of the ends unreliable. Using the first 639 nucleotide positions, for which unambiguous alignments could be obtained, we examine the neighbor-joining trees based on nucleotide divergences and based on conserved subsets of that data, including transversion and amino acid and second codon position divergences. Each of these subsets produces different trees, none of which can be easily reconciled with trees constructed using morphology and the fossil record. Bootstrap analysis using second codon positions strongly supports affinities between the order Blatteria (cockroaches) and the order Isoptera (termites) and between a wasp and the published honeybee sequence (Order Hymenoptera). The divergence of insect orders is very ancient and may have occurred too rapidly for easy resolution using mitochondrial protein sequences. Unambiguous resolution of insect orders will probably require analysis of many additional taxa, using the COII gene and other conserved sequences.     

世居及移居高原青少年最大有氧能力的特征

本文报道海拔３４１７ｍ和４２８０ｍ地区世居藏族和移居汉族青少年运动状态下心肺功能的对比研究。结果显示：３４１７ｍ和４２８０ｍ世居藏族的最大氧耗量、无氧阈值及最大心输出量都明显大于汉族,血氧饱和度（Ｓａｏ２）随运动负荷的增加而降低。海拔３４１７ｍ藏、汉族的△Ｓａｏ２分别为７．４６％和１０．０３％,４２８０ｍ处为８．５７％和１３．７５％,最大心率随海拔升高而下降。研究提示,藏族青少年有较高的最大有氧能力,反映了他们对低氧环境的适应优势。