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1.
Muscle fibers are generally fractionated into type I, IIA, and IIX fibers. Type I fibers specialize in long duration contractile activities and are found in abundance in elite endurance athletes. Conversely type IIA and IIX fibers facilitate short-duration anaerobic activities and are proportionally higher in elite strength and power athletes. A central area of interest concerns the capacity of training to increase or decrease fiber types to enhance high-performance activities. Although interconversions between type IIA and IIX are well recognized in the literature, there are conflicting studies regarding the capacity of type I and II fibers to interconvert. Therefore, the purpose of this article is to analyze the effects of various forms of exercise on type I and type II interconversions. Possible variables that may increase type II fibers and decrease type I fibers are discussed, and these include high velocity isokinetic contractions; ballistic movements such as bench press throws and sprints. Conversely, a shift from type II to type I fibers may occur under longer duration, higher volume endurance type events. Special care is taken to provide practical applications for both the scientist and the athlete.  相似文献   

2.
花楸(Sorbus pohuashanensis)导管分子穿孔板的类型及演化   总被引:12,自引:2,他引:10  
朱俊义 《植物研究》2002,22(3):285-288
对花楸茎次生木质部进行离析研究,发现其导管穿孔板有两种类型,即网状穿孔板和单穿孔板,并且还有5种过渡类型,具不同类型穿孔板的导管分子有3种类型,即两端均为网状穿孔板的导管分子;一端为网状穿孔板,另一端为单穿孔板的导管分子;两端的均为单穿孔板的导管分子,在花楸个体发育过程中穿孔板类型的演化重演了系统发育过程中导管网状穿孔板演化成单穿孔板的过程。  相似文献   

3.
凹叶厚朴细弱枝与粗壮枝导管分子的比较研究   总被引:5,自引:0,他引:5  
对凹叶厚朴粗壮枝和细弱枝的次生木质部进行离析研究,发现其导管穿孔板有两种类型,即单穿孔板和梯状穿孔板。在细弱枝中,具不同类型穿孔板的导管分子有八种类型,即一端为单穿孔板的导管分子,另一端为梯状穿孔板的导管分子;只有一端为单穿孔板的导管分子;只有一端为梯状穿孔板的导管分子;两端均为单穿孔板的导管分子;两端均为梯状穿孔板的导管分子;具三个单穿孔板的导管分子;两端具单穿孔板的导管分子,中间具多个梯状穿孔板的导管分子;具多个梯状穿孔板的导管分子。粗壮枝除了无具多个梯状穿孔板的导管分子外,其它细弱枝的导管分子的类型都具有。细弱枝的导管分子宽而长,粗壮枝导管分子窄而短。  相似文献   

4.
哺乳动物存活曲线类型的分析方法探讨   总被引:3,自引:0,他引:3  
动物的存活曲线通常可分为3种类型:凸型(Ⅰ型或A型)、直线型(Ⅱ型或B型)和凹型(Ⅲ型或C型)。存活率曲线与存活曲线在概念上有一定的区别。存活率要经过对数转换(或者直接采用对数标尺)后才能得到存活曲线类型,从动物的存活率曲线上直接判读存活曲线类型可能会导致错误的结论。鉴于存活曲线分析研究中出现的问题,建议在进行物种存活曲线类型的分析时,务必先进行对数转换。  相似文献   

5.
本文对南京地区771名汉族儿童的头面部16项指标及有关指数进行了测定。小儿面部容貌有随年龄变化而变化的特点。虽然小儿头型与成人一样,以短头型(包括过短头型)为主,但面型、鼻型与成人有显著区别,即面型以超阔面型和阔面型为主,中面型少见,狭面型更少;鼻型也多为阔鼻型。  相似文献   

6.
西藏地区已知鹅膏菌属(Amanita)真菌28种。西藏东南部的生态环境有利于该属种类的繁殖生长,约有90%以上的种集中分布在这里,同时反映了十分明显的垂直分布和对高山的适应特征。绝大多数种分布在海拔2500~3500m的森林带。另外该属全部种均属树木的外生菌根菌。本文还将鹅膏菌属的菌托初步划分为袋状型(Saccate type)、浅杯型(Vadosocupulatetype)、领口型(Collared type)、颗粒型(易碎型Granulate type)、小托型(Microvolvate type)、粉托型(Pulverulent type)等六种类型,并简要讨论了各种菌托类型与所处生态环境的适应性。  相似文献   

7.
Mammalian skeletal muscles are mixture of three type of fibers: type 1, type 2A, and type 2B fibers. Immunological studies and proteolytic analysis of myosin heavy chains from the three type of fibers have demonstrated the presence of distinct myosin isoforms. By using typed single muscle fibers and improving an electrophoretic method we are able to resolve three distinct polypeptides which are demonstrate to correspond to type 1, 2A and 2B myosin heavy chain isoforms by using specific monoclonal antibodies. The analysis of single muscle fibers shows that different myosin heavy chain isoforms are frequently coexpressed in the same muscle fiber.  相似文献   

8.
五味子属种子形态及其分类学意义   总被引:5,自引:1,他引:4  
用光学显微镜及扫描电镜对五味子属(Schisandra)10种96号样品的种子宏观形态和种皮的微观形态特征进行观察,首次对该属的种皮微观形态特征进行系统报道,并编排有分种检索表。研究结果表明:该属的种子宏观形态呈现平滑、细皱纹或瘤状突起,并认为五味子属种子形态可有从平滑到有细皱纹再到有瘤状突起的演化趋势;该属种皮表面微观形态可分为疣状突起型和网纹型。结合其它性状,本文认为网纹型所代表的两种植物应与本属中其它植物建立并列的分类单元。五味子属植物在种子形态特征上存在一定的差异,可为属以下、种以上的分类提供依据,并为探讨该属的系统演化提供有价值的参考资料。  相似文献   

9.
Naturally occurring new triterpenoid saponins reported from mid-1996 to March, 2007 are reviewed including their physical constants and plant sources, and are compiled in Table 1. New saponins are arranged in Table 1 on the basis of the skeletal structures of their aglycones, e.g., oleanane type, ursane type, lupane type, hopane type, taraxastane type, cycloartane type, lanostane type, tirucallane type, dammarane type, cucurbitane type, and holostane type. The known triterpenoid saponins and prosapogenins of the new saponins, the biological and pharmacological activities of which were published during 1996-2007, are also reviewed together with their plant sources listed in Table 2 according to the skeletal structures of their aglycones in the same fashion as in Table 1. The plant and animal sources of both new and known bioactive triterpenoid saponins are collected in Table 3 in alphabetical order. The biological and pharmacological activities such as antiallergic, antiatherosclerosis and antiplatelet, antibacterial, anticomplementary, antidiabetic, contraceptive, antifungal, anti-inflammatory, antileishmanial, antimalarial/antiplasmodial, anti-obesity, anti-proliferative, antipsoriatic, antispasmodic, antisweet, antiviral, cytotoxic/antitumor, detoxication, gastroprotective, haemolytic, hepatoprotective, immunomodulatory, anti-enzyme, anti-osteoporotic, insecticidal, insulin-like, membrane-porosity, molluscicidal, neuropharmacological, anti-endothelial dysfunction, snake venom antidote, and sweet activities of these saponins or derived prosapogenins are discussed briefly after Table 3.  相似文献   

10.
中亚鸢尾(Iris blowdowill)小孢子发生和雄配子体形成   总被引:1,自引:0,他引:1  
李宁  董玉芝  梁风丽 《植物研究》2005,25(2):140-143
选取中亚鸢尾为试材,通过石蜡切片的方法,对其小孢子发生和雄配子体发育进行了观察研究。中亚鸢尾花药壁发育方式为双子叶型,绒毡层为腺质;小孢子母细胞减数分裂时胞质分裂即有连续型,也有同时型。小孢子为四面体型和左右对称型,成熟花粉粒为二细胞。  相似文献   

11.
唐亚  谢嘉穗  高辉  孙辉 《广西植物》2005,25(5):441-446,i0006
基于文献和作者的研究,该文讨论了瓦形细胞的识别、类型、变异及在广义锦葵科中的分布及其系统学意义。瓦形细胞是一种特殊射线细胞,呈不定的横列,常分散在横卧细胞之间,常无细胞内含物,其宽度远比横卧细胞为小,根据瓦形细胞与横卧细胞高度、宽度的相对大小,分为榴莲型、中间型和翅子树型3种类型,目前为止仅在广义锦葵科9个亚科中的7亚科39个现存属和5个化石属中发现;榴莲型、翅子树型和中间型瓦形细胞分别在22、20和5个属中发现,具有中间型的属同时具有榴莲型或/和翅子树型。仅翅子树型和中间型瓦形细胞在化石中发现,榴莲型可能比翅子树型古老。瓦形细胞在广义锦葵科中的分布,对研究一些类群的系统发育有意义。  相似文献   

12.
A human erythrocyte cytosolic phosphatidylinositol-4-phosphate 5-kinase (PIP kinase) and a membrane-bound PIP kinase have been purified by phosphocellulose chromatography. Fractionation of the membrane-bound PIP kinase activities by phosphocellulose separated activity into two peaks, which eluted at 0.6 M NaCl (type I PIP kinase) and 1.0 M NaCl (type II PIP kinase). The cytosolic PIP kinase and the membrane-bound type II PIP kinase are 53 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, have indistinguishable 125I-peptide maps, and are immunochemically indistinguishable, suggesting that they are sequence identical. Antibodies raised to the cytosolic PIP kinase inhibit activity of both the membrane-bound type II and the cytosolic PIP kinases. The type I PIP kinase appears to be distinct from the cytosolic and membrane-bound type II PIP kinase; it is not immunocross-reactive, and antibodies toward type II PIP kinases do not inhibit type I PIP kinase. Further, membrane-bound type II PIP kinase can be removed from type I PIP kinase without loss of activity. Functional characterization of the PIP kinases demonstrates that the type I kinase has a 10-fold lower Km for PIP and a 5-fold higher Km for ATP compared with the type II enzymes. The type I and type II (membrane-bound or cytosolic) PIP kinases are modulated differentially by spermine and heparin. Finally, the type I PIP kinase phosphorylates intrinsic PIP on isolated erythrocyte membranes, whereas the type II PIP kinases have no activity toward native membranes.  相似文献   

13.
Resin canal patterns in the Pinaceae differ significantly from those in other conifers. In this paper, Pinus type, Picea type and Larix type are defined.Pinus has the Pinus type pattern, in spite of the possession of a system of peripheral canals in some members. The patterns inAbies, Picea, Cedrus, Keteleeria andPseudotsuga are varied. Both Pinus and Picea types are usually observed, although many other types are also seen in these five genera.Larix andPseudolarix have the Larix type pattern, andTsuga has a modified Torreya type pattern. From the data obtained in the present series of studies (Suzuki, 1979a, b), two main evolutional trends of resin canal patterns are suggested. In the Pinaceae, the patterns probably evolved from the complicated type to the simple type. In the other families, they evolved from the simple type to the complicated type. Moreover, it is to be considered likely that the patterns have evolved independently in each family. Patterns of resin canals are very similar to the primary vascular patterns. The similarity is probably not fundamental, but superficial, because most of the conifer species, of which resin canal patterns are varied, have but a single type of the primary vascular system.  相似文献   

14.
山东广义苦荬菜属(菊科)叶表皮微形态的研究   总被引:1,自引:0,他引:1  
高召兰  李法曾   《广西植物》2007,27(3):435-439
对山东广义苦荬菜属植物叶表皮微形态进行了光镜下的观察研究。结果表明:山东广义苦荬菜属9种植物叶表皮微形态可分为四种类型:(1)小苦荬型:上、下表皮均有气孔器,气孔器为不规则型,偶有非典型不等型,上、下表皮细胞为不规则形,垂周壁波状;(2)黄瓜菜型:上表皮无气孔器,下表皮气孔器为不规则型,偶有非典型不等型,上、下表皮细胞为不规则形,垂周壁深波状;(3)沙苦荬型:上、下表皮均有气孔器,气孔器为不规则型,偶有非典型不等型,上、下表皮细胞为多边形,垂周壁平直、弓形;(4)苦荬菜型:上、下表皮均有气孔器,气孔器为不规则型,偶有非典型不等型,上表皮细胞为不规则形,垂周壁波状,下表皮细胞为多边形,垂周壁弓形;与中国植物志把广义苦荬菜属划分为4个属的意见相一致。  相似文献   

15.
秦艽的胚胎学研究   总被引:11,自引:1,他引:10  
秦艽具5个雄蕊,花药壁的发育属于双子叶型,为变形绒毡尾,花粉母细胞减粉分裂时的胞质分裂为同时型,四分孢子主要呈四面体型,成熟花粉粒球形,具3-孔沟,多为2细胞。子房一定,中轴胎座,其上着生众多具单珠被,薄珠心的倒生胚珠,大孢子母细胞减数分裂形成线型四分体。合点端大孢子继续发育,少数为合点端第二个大孢子形成功能大孢子,胚囊发育属蓼型,受精作用属于有丝分裂前配子融合类型,胚按茄型发育,胚乳核型,胚乳早  相似文献   

16.
Abstract Actinobacillus pleuropneumoniae serotype 2 secretes type II haemolysin and pleurotoxin activities. Here, the genes for type II haemolysin were cloned in Escherichia coli , but type II haemolysin antigen and haemolysin activity were only detected intracellularly and not exported to culture supernatant. It has been reported that the genes for type II haemolysin are not linked to functional secretion genes, while those for pleurotoxin are. In this report the means of secretion of type II haemolysis was examined by constructing a hybrid plasmid carrying the genes required for type II haemolysin expression, together with determinants which allow secretion of pleurotoxin and are linked to the pleurotoxin toxin genes. These genes facilitated the export of type II haemolysin from E. coli , and may perform this function in A. pleuropneumoniae .  相似文献   

17.
Hoffmann AA  Turelli M 《Genetics》1988,119(2):435-444
In California, Drosophila simulans females from some populations (type W) produce relatively few adult progeny when crossed to males from some other populations (type R), but the productivity of the reciprocal cross is comparable to within-population controls. These two incompatibility types are widespread in North America and are also present elsewhere. Both types sometimes occur in the same population. Type R females always produce type R progeny irrespective of the father's type. However, matings between R males and females from stocks classified as type W produce type R progeny at low frequency. This suggests rare paternal transmission of the R incompatibility type, as we have found no evidence for segregation of incompatibility types in the W stocks. There is quantitative variation among type R lines for compatibility with W females, but not vice versa. Population cage studies and productivity tests suggest that deleterious side effects are associated with the type R cytoplasm.  相似文献   

18.
在光学显微镜和扫描电镜下,对栒子属(Cotoneaster Medikus)2组15种植物的叶表皮特征进行了观察,发现疏花组(Sect. Cotoneaster)植物叶表皮细胞多为多边形,垂周壁一般为平直—弓形,气孔均为无规则型;单花组(Sect. Uniflos)植物叶表皮细胞常不规则型,垂周壁多浅波状,气孔除无规则型(anomocytic)外还兼有十字型(staurocytic)、四分体型(tetracytic)和等三体型(isotricytic)。依据气孔周围角质膜特征等叶表皮性状,把15种植物分为W型、S型和I型,其中W型是S型的特化类型,疏花组的种类为W型或S型,单花组的种类为I型。叶表皮微形态特征可以为栒子属植物组及种的分类学处理提供解剖学资料。  相似文献   

19.
Secretory and motility reflexes are evoked by physiological stimuli in the isolated rat distal colon, which is therefore expected to contain intrinsic primary afferent (sensory) neurons. Dogiel type II neurons (putative intrinsic primary afferent neurons) exhibit several long processes emerging from large oval or round cell bodies. This study has examined the immunohistochemical characteristics of type II neurons in the submucosal plexus of rat distal colons by using whole-mount preparations. Neuronal cell bodies positive for both substance P (SP) and calretinin have been observed in colchicine-treated rats. Neurofilament 200 immunostaining has confirmed the type II morphology of SP-positive neurons. Moreover, all submucosal type II neurons identified by neurofilament 200 immunoreactivity are positive for calretinin. Calcitonin gene-related peptide (CGRP)-positive neurons in the submucosal plexus are distinct from type II neurons because they are negative for calretinin and have smaller cell bodies than the SP-positive submucosal type II neurons. Most (73%) of the submucosal neurons including type II neurons exhibit immunoreactivity for the neurokinin-1 receptor (NK1R), a receptor for SP, on the surface of cell bodies. Immunoreactivity for the EP3 receptor (EP3R), a receptor for prostaglandin E2, has been detected in 51% of submucosal neurons including type II neurons. Thus, submucosal type II neurons in the rat distal colon are immunopositive for SP/calretinin but immunonegative for CGRP. SP released from submucosal type II neurons probably acts via NK1Rs on type II and non-type II submucosal neurons to mediate intrinsic reflexes. EP3R-positive submucosal type II neurons may be potential targets of prostaglandin E2.  相似文献   

20.
The low temperature (77 K) irradiation of oxidized ceruloplasmin and Rhus vernicifera laccase at the 330 nm absorption which arises from type 3 copper leads to the reduction of type 1 copper as demonstrated by bleaching of the 610 nm chromophore and the decrease of the EPR signal associated with this species. Type 2 copper remains unaffected. Concomitant with the type 1 copper reduction, a new EPR signal which is possibly that of a biradical appears. Upon thawing, type 1 copper is reversibly oxidized and the radical signal disappears. Irradiation of oxidized protein at the absorption band of type 1 copper produces no spectral change. An EPR study at room temperature confirms the wave-length specificity and reversibility of the photoreduction of type 1 copper and radical formation. Radical appearance and disappearance at room temperature are extremely slow (tau1/2 approximately 30 min). Optical studies at room temperature show that upon anaerobic irradiation of laccase in the 330 nm absorption band, both type 3 and type 1 chromophores are slowly reduced. Upon return to the dark and in the presence of O2, both type 3 and type 1 centers are reoxidized. Oxidizing equivalents either from O2 or K3Fe(CN)6 are required for the reoxidation reaction. These studies demonstrate that there is a direct energy transfer between type 3 and type 1 copper sites in blue copper oxidases.  相似文献   

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