Comment on "Protein sequences from mastodon and Tyrannosaurus rex revealed by mass spectrometry"

We used authentication tests developed for ancient DNA to evaluate claims by Asara et al. (Reports, 13 April 2007, p. 280) of collagen peptide sequences recovered from mastodon and Tyrannosaurus rex fossils. Although the mastodon samples pass these tests, absence of amino acid composition data, lack of evidence for peptide deamidation, and association of alpha1(I) collagen sequences with amphibians rather than birds suggest that T. rex does not.     

Protein sequences from mastodon and Tyrannosaurus rex revealed by mass spectrometry

Fossilized bones from extinct taxa harbor the potential for obtaining protein or DNA sequences that could reveal evolutionary links to extant species. We used mass spectrometry to obtain protein sequences from bones of a 160,000- to 600,000-year-old extinct mastodon (Mammut americanum) and a 68-million-year-old dinosaur (Tyrannosaurus rex). The presence of T. rex sequences indicates that their peptide bonds were remarkably stable. Mass spectrometry can thus be used to determine unique sequences from ancient organisms from peptide fragmentation patterns, a valuable tool to study the evolution and adaptation of ancient taxa from which genomic sequences are unlikely to be obtained.     

Comment on "Protein sequences from mastodon and Tyrannosaurus rex revealed by mass spectrometry"

Asara et al. (Reports, 13 April 2007, p. 280) reported sequencing of Tyrannosaurus rex proteins and used them to establish the evolutionary relationships between birds and dinosaurs. We argue that the reported T. rex peptides may represent statistical artifacts and call for complete data release to enable experimental and computational verification of their findings.     

An El Jobo Mastodon Kill at Taima-taima, Venezuela

Excavation at Taima-taima in 1976 recovered artifacts of the El Jobo complex in direct association with the butchered remains of a juvenile mastodon. Radiocarbon dates on associated wood twigs indicate a minimum age of 13,000 years before the present for the mastodon kill, a dating significantly older than that of the Clovis complex in North America. The El Jobo complex must have evolved independently in northern South America.     

不同比例玉米和豆粕日粮对泌乳獭兔生产性能的影响

[目的]研究不同比例玉米和豆粕日粮对泌乳獭兔生产性能的影响,筛选最佳饲料配方。[方法]选用80只同期分娩,体重相近健康泌乳獭兔,随机分为5组,16只/组。Ⅰ、Ⅱ、Ⅲ、Ⅳ组为试验组,分别饲喂单玉米型日粮、单豆粕型日粮、双兼型日粮和双无型日粮。Ⅴ组为对照组,饲喂常规玉米豆粕型日粮。饲喂30 d后,检测其对母兔泌乳性能、仔兔生长速度、体重及饲料成本的影响。[结果]试验Ⅴ组泌乳獭兔的泌乳性能和仔兔生长速度均与对照组相近,差异不显著;Ⅲ组仔兔断奶成活率最高,差异不显著;其他试验组均明显低于对照组,差异显著（P〈0.05）;Ⅰ、Ⅱ和Ⅲ组母兔体重变化与对照组相比均差异不显著;Ⅳ组母兔失重明显高于对照组和其他试验组,差异极显著（P〈0.01）。试验组饲料成本均低于对照组。[结论]日粮中适当的玉米和豆粕比例,不仅可以降低饲养成本,而且可获得最佳的饲养效果。     

芍药栽培品种ISSR反应体系的优化和应用

以栽培芍药为材料,通过对ISSR-PCR反应体系中的Mg~(2 )、dNTP和Tag DNA聚合酶浓度的优化,以改进芍药的ISSR反应体系;从55对引物中筛选出4对有稳定扩增结果的引物;用这4对引物对22个芍药栽培品种的DNA进行扩增,其所得扩增产物与所选芍药性状经过数据处理后,用MATLAB软件分别进行聚类分析,结果表明供试芍药品种皆可分为3个类群,其分子标记与性状的聚类分析间有较强的相关性。     

中国大麦地方品种的遗传多样性及α-淀粉酶活性的 全基因组关联分析

【目的】了解中国大麦地方品种的遗传多样性,为大麦α-淀粉酶活性基因寻找有效的分子标记。【方法】利用覆盖全基因组的41对简单重复序列（SSR）标记引物,对257份中国大麦地方品种进行PCR扩增;采用Nei’s遗传距离和邻接（neighbour-joining）法进行聚类分析;在对群体结构和连锁不平衡分析的基础上,进行基于全基因组的表型与基因型的关联分析。【结果】共鉴定出709个等位变异,平均每个位点的等位变异数为17个。41个SSR标记位点的多态性信息指数（PI）变化范围为0.23（Bmag 0385）—0.94（Bmac0032）,平均为0.6385。257个中国大麦地方品种聚合成9个不同的结构类群,发现5个与大麦α-淀粉酶活性显著关联的标记位点。【结论】中国大麦地方品种中蕴藏着丰富的遗传等位变异;各类群的特性和品种来源符合“遗传关系密切、表型特征特性相同、地理生态相近”的同类群聚集规律。在5个关联位点中,位于7H染色体上的Bmag0385位点,其等位变异A215的酶活增强效应最大;此外,7H上Bmac0273的等位变异A141的增效作用较大,可用于啤酒大麦育种的分子标记辅助选择。     

Analyses of soft tissue from Tyrannosaurus rex suggest the presence of protein

We performed multiple analyses of Tyrannosaurus rex (specimen MOR 1125) fibrous cortical and medullary tissues remaining after demineralization. The results indicate that collagen I, the main organic component of bone, has been preserved in low concentrations in these tissues. The findings were independently confirmed by mass spectrometry. We propose a possible chemical pathway that may contribute to this preservation. The presence of endogenous protein in dinosaur bone may validate hypotheses about evolutionary relationships, rates, and patterns of molecular change and degradation, as well as the chemical stability of molecules over time.     

Requirement for positive selection of gamma delta receptor-bearing T cells.

The alpha beta and gamma delta T cell receptors for antigen (TCR) delineate distinct T cell populations. TCR alpha beta-bearing thymocytes must be positively selected by binding of the TCR to major histocompatibility complex (MHC) molecules on thymic epithelium. To examine the requirement for positive selection of TCR gamma delta T cells, mice bearing a class I MHC-specific gamma delta transgene (Tg) were crossed to mice with disrupted beta 2 microglobulin (beta 2M) genes. The Tg+beta 2M- (class I MHC-) offspring had Tg+ thymocytes that did not proliferate to antigen or Tg-specific monoclonal antibody and few peripheral Tg+ cells. This is evidence for positive selection within the gamma delta T cell subset.     

壳寡糖对秋海棠叶片离体培养的影响

[目的]明确壳寡糖(COS)用于秋海棠叶片离体培养的可行性。[方法]以MS为基本培养基,添加不同浓度的壳寡糖和1.5 mg/L2,4-D(对照),对秋海棠叶片进行离体培养。[结果]对照处理的秋海棠叶片离体培养的效果最好。壳寡糖在秋海棠叶片培养中可起到生长激素的作用,最适合诱导愈伤组织的浓度是1.5 mg/L,继代增殖和不定芽分化效果最好的浓度是1.52、.0 mg/L,诱导生根效果最好的浓度为1.5 mg/L,浓度为0.75%~1.00%壳寡糖溶液浇灌的幼苗成活率最高,达90%以上;同时对培养基及外植体起到了防污抗病的保护作用。[结论]秋海棠叶片离体培养时,培养基中的壳寡糖浓度以1.5 mg/L为宜。     

中草药饲料添加剂对獭兔肉品质的影响

[目的]为中草药饲料添加剂在獭兔养殖业中的推广应用提供理论依据。[方法]将108只40日龄断奶獭兔分成3组（每组36只）,A组饲喂基础日粮;B组饲喂基础日粮＋0.3%中草药饲料添加剂;C组饲喂基础日粮＋0.4%中草药饲料添加剂。饲养至150日龄时,测定肌肉品质指标。[结果]各组间pH值、失水率、贮存损失率、粗蛋白含量差异显著（P〈0.05）;嫩度、熟肉率、水分含量、粗脂肪含量差异不显著（P〉0.05）。氨基酸总量,必需和半必需氨基酸总量,主要鲜味氨基酸总量C组最高,为23.84%、11.47%、8.32%;B组次之,为20.94%、10.64%、6.81%;A组（对照组）最低,为19.06%、9.61%、6.46%,[结论]该中草药饲料添加剂能改善獭兔肉品质,最佳添加量为0.4%。     

中国4个弓形虫虫株GRA6基因的比较分析

 通过对国内来源于不同宿主的ZS人株、SH人株、CN猪株、QH绵羊株4个弓形虫虫株，以及国际标准强毒株RH株的致密颗粒抗原（GRA6）基因进行PCR-RFLP分析，首次对中国弓形虫虫株进行了基因分型研究，旨在了解中国弓形虫基因型的分布情况，从而为进一步的分子遗传学研究以及弓形虫病的防制提供资料。PCR-RFLP分析显示两种带型：RH、SH、CN 3株弓形虫为一种带型，QH和ZS 2株弓形虫为另一种电泳带型。GRA6序列分析结果显示：RH、SH、CN 3株弓形虫的GRA6基因序列上的MseΙ酶切位点与国外报道的RH株一致，同属于基因型Ι，为强毒株；QH和ZS 2株弓形虫的MseΙ酶切位点与国外报道的弱毒株BEVERLEY株和ME49株一致，同属于基因型Ⅱ，与PCR-RFLP分析结果一致。除MseΙ酶切位点外，中国的几个虫株GRA6序列与GenBankTM注册的RH株及BEVERLEY和ME49两个弱毒株有个别碱基的差异。结果证明中国人源弓形虫包含了Ι、Ⅱ两种基因型，而动物源性弓形虫则因宿主和来源地不同亦有Ι、Ⅱ两个基因型。     

复方中药对断奶獭兔盲肠内环境及脾脏IFN-γ、IL-10 mRNA表达的影响

【目的】研究复方中药（cCHM）添加剂对断奶獭兔盲肠内环境及脾脏IFN-γ、IL-10 mRNA表达的影响,探讨其对机体抗病能力的调控作用及适宜用量。【方法】选用（35±2）日龄断奶、体质量相近的獭兔144只,随机分为对照组和3个试验组,每组6个重复,每重复6只幼兔。对照组饲喂添加0.1 g/kg杆菌肽锌的日粮（不含抗生素等其他药物）,试验组分别饲喂添加复方中药5 g/kg（cCHM1组）、10 g/kg（cCHM2组）、20 g/kg（cCHM3组）的日粮,60 d后,取脾脏和盲肠样品,测定盲肠微生物活力和数量,检测IFN-γ、IL-10的相对表达量。【结果】与对照组相比,cCHM2组獭兔盲肠内容物氨氮（NH₃-N）浓度降低21.62%,菌体蛋白（MCP）含量提高16.81%,差异显著（P＜0.05）。复方中药抑制大肠杆菌的效果不及抗生素,但cCHM2组、cCHM3组乳酸杆菌数量较对照组分别提高18.31%和16.50%,差异显著（P＜0.05）。复方中药提高了脾脏IFN-γ、IL-10 mRNA的相对表达量,cCHM2组和cCHM3组均极显著高于对照组（P＜0.01）。【结论】复方中药添加剂可改善断奶獭兔盲肠内环境,增强机体的免疫功能,有利于断奶獭兔的肠道健康;该试验条件下复方中药添加剂的适宜用量为10 g/kg。     

Kimmswick: a clovis-mastodon association in eastern missouri

Stone tools characteristic of the Clovis culture have been found in direct association with bones of the American mastodon at Kimmswick, Missouri. The vertebrate fauna from Clovis components suggests a deciduous woodland and meadow habitat. Such an environmental reconstruction provides a new perspective for Clovis adaptations and the ecological tolerances of Mammut americanum.     

蟆叶秋海棠离体培养的研究

以蟆叶秋海棠(Begonia rex)的幼嫩叶片为外植体,采用L25(55)正交设计,研究了不同生长调节剂和培养基对愈伤组织诱导的影响.结果表明,培养基的类型对愈伤组织诱导的影响极大,生长调节荆对愈伤组织诱导有一定的影响,愈伤组织在不添加任何生长调节剂的培养基上即可进行分化.蟆叶秋海棠最佳愈伤组织诱导培养基组合为1/2 MS+0.5～1.5 mg·L-1 KT+0.5 mg·L-16-BA+0.5～2.0 mg·L-1α-NAA+0.8%琼脂+3%蔗糖,愈伤组织诱导率可高达100%.生根培养基为1/2 MS+0.2 mg·L-1α-NAA+0.8%琼脂+3%蔗糖,生根率高达100%.