Evolution of the mitochondrial DNA cytochrome b gene in Tetraonidae birds

Mitochondrial fragments containing the cytochrome b gene (1020 bp in size) of four bird species belonging to four genera of the family Tetraonidae (Tetrao parvirostris, Bonasa umbellus, Lagopus lagopus scoticus, and Falcipennis falcipennis) were directly sequenced. Of the 1020 nucleotide positions, 186 were variable and uniformly distributed over the gene and only 46 were parsimony informative. Most substitutions were synonymous. Replacement substitutions were detected for 15 out of 340 amino acid sites; only four replacements were parsimony informative. The greatest codon bias was found for leucine and serine. The C-T transitions and the G-C transversions were, respectively, the most common (60.7%) and the most rare (5.9%). The mutation frequencies were high at the third codon position (85.2%) and relatively low at the first and the second position. At the third codon position of the species examined, the guanine content was the lowest (3.3%) and the cytosine content was the highest (44.5%). Based on the cytochrome b gene sequences, phylogenetic relationships in the order Galliformes are inferred.     

New insights into the systematics of the enigmatic Polynesian sandpipers Aechmorhynchus parvirostris and Prosobonia leucoptera

With only a single extant representative, endemic to the Tuamotu Archipelago, the Polynesian sandpipers (Aechmorhynchus and Prosobonia) may have had a larger distribution in Eastern Polynesia in the past, with four endemic taxa. Although these aberrant sandpipers' membership to the Scolocapidae has been well supported, finding their closest living taxa has proved difficult and the phylogenetic relationships of these taxa have remained unresolved. We present the first molecular analysis of the Polynesian sandpipers, including sampling of the only known specimen of the extinct Prosobonia leucoptera, collected in 1773. Based on mitochondrial and nuclear gene sequence data, the phylogenetic analyses demonstrate that the Polynesian sandpipers were sister taxa and belonged to the clade that included the other sandpipers (Calidris and allies) and turnstones (Arenaria), although without a close relative among extant genera. Divergence time estimates suggested that the lineage leading to Prosobonia diverged from the other extant sandpipers during the Oligocene and that either the Line Islands or the Tuamotu Archipelago were probably the first archipelagos colonized by the Prosobonia lineage. On the basis of these results, we suggest that Aechmorhynchus parvirostris and Prosobonia leucoptera be regarded as related species within the same genus, and thus that the senior name Prosobonia be used for both taxa.     

基于RS和GIS技术的河北省鸡形目鸟类分布格局

收集和整理河北省鸡形目鸟类的分布资料,借助GIS的绘图功能,把解译的遥感影像数据数字化为植被类型图和地貌图;根据文献和标本记录的地理位置和野外考察记录,做出河北省鸡形目鸟类的点分布图;根据鸡形目鸟类与其生境之间的相互依赖关系,定义鸡形目鸟类的适宜生境类型,利用GIS技术的分析、提取和叠加功能,提取每种鸡形目鸟类的适宜生境类型图,预测河北省鸡形目鸟类的总体分布格局。结果表明：河北省鸡形目鸟类物种丰富度地区主要集中在坝上高原区和燕山太行山山地区;河北省鸡形目鸟类可分为全省广布种(鹌鹑和雉鸡)、燕山太行山山地和坝上高原分布种(石鸡、斑翅山鹑、勺鸡)和局部地区特征种(黑琴鸡、黑嘴松鸡、花尾榛鸡、褐马鸡)3种类型。     

紫貂冬季食性的分析

１９９１至１９９８年的三个冬季,在大兴安岭地区共收集紫貂粪样２２３个．食性分析结果表明,紫貂冬季食物主要为小型哺乳类（５４．１％）、植物浆果和种子（３２．４％）、鸟类（１２．５％）和昆虫（１．０％）．在紫貂选择的７种小型哺乳类中,主要以棕背（２７．３％）和红背（１９．２％）为食,其次为雪兔和冬眠的花鼠。对于鸟类,紫貂主要捕食花尾榛鸡（８．１％）,松鸦（０．７％）,大山雀（０．５％）和黑啄本鸟等。有２．２％的粪样中含有小型鸟的卵壳、紫貂的植物性食物主要为越桔浆果（２０．８％）和偃松种籽（８．８％）。昆虫中只有蚂蚁在紫貂食性中出现（１．０％）．紫貂冬季食物构成没有年度间差异（Ｐ＞０．０５）。通过捕食迹,我们还发现紫貂捕食黑嘴松鸡。虽然红背的捕获率（７９．４％）高于棕背（２．９％）,但食性分析结果却相反,说明紫貂更喜欢捕捉身体较大的鼠类。有较强气味的中虽有一定的数量,但在紫貂冬季食物中未出现过。     

Science,medicine, and the future. Hypertension.

The abundance of drugs now available for treating hypertension, and evidence that small reductions in blood pressure reverse the associated risk of stroke have shifted clinical concerns away from hypertension. However, we do not understand the cause of hypertension in 95% of patients, fail to achieve a normal blood pressure in 50% of patients, and are unable fully to reverse the cardiac and vascular changes that predate the diagnosis and treatment of hypertension. Consequently, hypertension remains the commonest cause of strokes in Britain and of renal failure in the United States. Essential hypertension is a polygenic disease whose understanding can now be advanced through molecular genetic analyses. Several different syndromes are likely to be recognised; most will be due to interactions between genetic and environmental factors, but there are also likely to be further monogenic syndromes in families with multiple affected members. Recognition of these syndromes will permit accurate genetic prediction of prognosis and optimal treatment and perhaps lead to new and more powerful classes of antihypertensive treatment.     

Prostaglandins,the kidney,and hypertension.

Prostaglandins are part of the family of oxygenated metabolites of arachidonic acid known collectively as eicosanoids. While they are formed, act, and are inactivated locally and rarely circulate in plasma, they can affect blood flow in some tissues and so might contribute to the control of peripheral vascular resistance. Few studies have shown any derangement of total body prostaglandin synthesis or metabolism in hypertension, but increased renal synthesis of one prostanoid, thromboxane A2, has been noted in spontaneously hypertensive rats and some hypertensive humans. This potent vasoconstrictor may account for the increased renal vascular resistance and suppressed plasma renin activity seen in many patients with hypertension. Increased renal vascular resistance could increase the blood pressure directly as a component of total peripheral resistance or indirectly by increasing glomerular filtration fraction and tubular sodium reabsorption. Specific thromboxane synthesis inhibitors not only decrease renal thromboxane production but also increase renal vasodilator prostaglandin synthesis when prostaglandin synthesis is stimulated. This redirection of renal prostaglandin synthesis toward prostacyclin might be of benefit in correcting a fundamental renal defect in patients with hypertension.