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。     

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.     

Insecticidal Activity of Bacillus thuringiensis Cry1Bh1 against Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) and Other Lepidopteran Pests

Bacillus thuringiensis is an important source of insect resistance traits in commercial crops. In an effort to prolong B. thuringiensis trait durability, insect resistance management programs often include combinations of insecticidal proteins that are not cross resistant or have demonstrable differences in their site of action as a means to mitigate the development of resistant insect populations. In this report, we describe the activity spectrum of a novel B. thuringiensis Cry protein, Cry1Bh1, against several lepidopteran pests, including laboratory-selected B. thuringiensis-resistant strains of Ostrinia nubilalis and Heliothis virescens and progeny of field-evolved B. thuringiensis-resistant strains of Plutella xylostella and Spodoptera frugiperda. Cry1Bh1 is active against susceptible and B. thuringiensis-resistant colonies of O. nubilalis, P. xylostella, and H. virescens in laboratory diet-based assays, implying a lack of cross-resistance in these insects. However, Cry1Bh1 is not active against susceptible or Cry1F-resistant S. frugiperda. Further, Cry1Bh1 does not compete with Cry1Fa or Cry1Ab for O. nubilalis midgut brush border membrane binding sites. Cry1Bh1-expressing corn, while not completely resistant to insect damage, provided significantly better leaf protection against Cry1Fa-resistant O. nubilalis than did Cry1Fa-expressing hybrid corn. The lack of cross-resistance with Cry1Ab and Cry1Fa along with independent membrane binding sites in O. nubilalis makes Cry1Bh1 a candidate to further optimize for in-plant resistance to this pest.     

Chemistry of the consumption and excretion of the bumphead parrotfish (Bolbometopon muricatum), a coral reef mega-consumer

Coral Reefs - Bolbometopon muricatum are ecologically unique mega-consumers in coral reef ecosystems. They primarily divide their dietary intake between living scleractinian corals and coral rock,...     

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.

     

Ribozymes targeted to stearoyl-ACP delta9 desaturase mRNA produce heritable increases of stearic acid in transgenic maize leaves.

Ribozymes are RNAs that can be designed to catalyze the specific cleavage or ligation of target RNAs. We have explored the possibility of using ribozymes in maize to downregulate the expression of the stearoyl-acyl carrier protein (Delta9) desaturase gene. Based on site accessibility and catalytic activity, several ribozyme constructs were designed and transformed into regenerable maize lines. One of these constructs, a multimer hammerhead ribozyme linked to a selectable marker gene, was shown to increase leaf stearate in two of 13 maize lines. There were concomitant decreases in Delta9 desaturase mRNA and protein. The plants with the altered stearate phenotype were shown to express ribozyme RNA. The ribozyme-mediated trait was heritable, as evidenced by stearate increases in the leaves of the R1 plants derived from a high-stearate line. The increase in stearate correlated with the presence of the ribozyme gene. A catalytically inactive version of this ribozyme did not produce any significant effect in transgenic maize. This is evidence that ribozymes can be used to modulate the expression of endogenous genes in maize.     

Relationships in the Drosophila obscura species group, inferred from mitochondrial cytochrome oxidase II sequences

We compare the sequences for the mitochondrial cytochrome oxidase II gene of 13 species of the Drosophila obscura group. The survey includes six members of the D. affinis subgroup, four of the D. pseudoobscura subgroup, and three of the D. obscura subgroup. In all species, the gene is 688 nucleotides in length, encoding a protein of 229 amino acids plus the first position T of the stop codon. The sequences show the typical high-transition bias for closely related species, but that bias is essentially eliminated for species pairs of > 5% sequence divergence. The phylogenetic relationships in the species group are inferred using both neighbor-joining and maximum parsimony. The two procedures give comparable results, showing that the D. affinis and D. pseudoobscura subgroups are monophyletic groupings that appear to have closer affinities to one another than either has to the D. obscura subgroup. We use transversion distances to estimate times of divergence, on the basis of three different estimates of the time of separation of the D. obscura species group from the D. melanogaster group. If that event occurred 35 Mya, then we can estimate the origin of the nearctic forms at approximately 22 Mya and the separation of the D. affinis and D. pseudoobscura subgroups at approximately 17 Mya.