首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Transferrin is the major iron transporter in blood plasma, and is also found, at lower concentrations, in saliva. We studied the synthesis and secretion of transferrin in rat parotid acinar cells in order to elucidate its secretory pathways. Two sources were identified for transferrin in parotid acinar cells: synthesis by the cells (endogenous), and absorption from blood plasma (exogenous). Transferrin from both sources is secreted from the apical side of parotid acinar cells. Endogenous transferrin is transported to secretory granules. It is secreted from mature secretory granules upon stimulation with a β-adrenergic reagent and from smaller vesicles in the absence of stimulation. Exogenous transferrin is internalized from the basolateral side of parotid acinar cells, transported to the apical side by transcytosis, and secreted from the apical side. Secretory processes for exogenous transferrin include transport systems involving microfilaments and microtubules.  相似文献   

2.
The status of all of the putative member genera of the subfamily Aephnidiogeninae is reconsidered, based mainly on the morphology of the terminal genitalia. Aephnidiogenes Nicoll, 1915 is the only genus retained in the Aephnidiogeninae. Aephnidiogenes major Yamaguti, 1934 from Diagramma labiosum from the southern Great Barrier Reef is redescribed with particular reference to the terminal genitalia, and is shown to lack a true cirrus-sac, a condition considered to be diagnostic of the Aephnidiogeninae. Holorchis Stossich, 1901 is placed in the subfamily Lepidapedinae. Holorchis pycnoporus Stossich, 1901 from Pagellus acarne from off Spanish Sahara and from Diplodus vulgaris from off Italy and H. legendrei Dollfus, 1946 from Sparodon durbanensis and D. sargus from off eastern Cape Province, South Africa and from Pagellus erythrinus from the Adriatic Sea and Italy are studied and illustrated. The terminal genitalia of H. pycnoporus are found to be enigmatic, but those of H. legendrei are found to fit clearly into the 'Lepidapedon-like' pattern. A new genus Austroholorchis is erected in the Lepidapedinae, with A.sprenti (Gibson, 1987) n. comb. as the type-species. Its diagnostic features are its ani, infundibuliform oral sucker and the position of the ovary at about mid-level of the uterus . A. sprenti is illustrated, its hosts in Queensland waters being Sillago maculata, S. analis and S. ciliata. A. levis n. sp. is described from Sillago bassensis from south-western Western Australia. The genus PseudaephnidiogenesYamaguti, 1971 is placed in the Lepidapedinae. P. rhabdosargi (Prudhoe, 1956) from Rhabdosargus sarba from off Natal, South Africa is illustrated and the terminal genitalia of P. rhabdosargi from R. sarba and from R. holubi from off eastern Cape Province and Pseudaephnidiogenes rossi Bray, 1985 from Caffrogobius nudiceps from off eastern Cape Province, South Africa are illustrated. The genus Pseudoholorchis Yamaguti, 1958 is placed in the subfamily Lepocreadiinae. The terminal genitalia of P. pulcher (Manter, 1954) from Latridopsis ciliaris from New Zealand are illustrated. The genus Neolepocreadium Thomas, 1960 is placed in the Lepocreadiidae.  相似文献   

3.
Three species are discussed: Teloschistes hosseusianus Gyelnik, formerly known only from the type locality in Argentina is shown to have a wider distribution in South America. T. stellatus (Mey. & Flot.) Mull. Arg. known only from the type locality in Peru is reported from other localities in Peru and Chile. T. velifer F. Wils. previously known from Australia and New Zealand is reported from six localities in Chile. One of these is T. hollermayeri Ras. which is a synonym of T. velifer. A key is given to the 11 species of Teloschistes so far known from South America.  相似文献   

4.
Abstract Aphis clerodendri Matsumura is newly recorded from Australia and is known from the Northern Territory, on islands in Torres Strait, and in rainforest in northern Queensland and New South Wales. It induces the formation of leaf pseudogalls on native species of Clerodendrum and is commonly attended by ants, which penetrate and may polydomously nest in the galls. Previously known only from eastern Asia, A. clerodendri can now be classified as native to Australia and Australasian in natural distribution. The species is also newly recorded from Papua New Guinea and Vietnam.  相似文献   

5.
Six species in two genera of Darwinulidae are herereported from Europe; two of these are known fromfossils only.Microdarwinula zimmeri (Menzel) is, in Europe,an interstitial species. Darwinula stevensoni(Brady & Robertson), the type species of thegenus, is also the most common darwinulid. Althoughit abounds in the shallow littoral of lakes, it canalso occur in rivers, bogs and springs, both infresh and saline waters. Darwinula boteaiDanielopol is found in interstitial habitats inRumania. Darwinula pagliolii Pinto & Kotzian,originally described from Recent South Americanpopulations, is reported from fossil, Germanlocalities. Darwinula brasiliensis Pinto &Kotzian, originally described as D. africanabrasiliensis, also from South America, is hereelevated to specific rank. It has been found extantin a bog in southern France and is reported from amuseum collection from a Scottish lake. The latterspecies is here reported from Europe for the firsttime. Finally, Darwinula danielopoli n.sp. isalso described from German Holocene (Subrecent)fossils. This species represents the first nominaltaxon of a distinctly separate lineage within Darwinula s.l.Global and European distribution, history,ecological tolerance ranges, brooding and clonaltaxonomy in this group are discussed.  相似文献   

6.
New land tortoises (Testudines: Testudinidae) from the Miocene of Africa   总被引:1,自引:0,他引:1  
The described fossil testudinids from the Miocene of Africa are reviewed. Geochelone stromeri sp. nov . is described from Lower Pliocene (Langebaanweg) and Miocene (Namib) specimens. Kinixys erosa , an extant species, is reported from Songhor Hill. Chersina sp. is reported from Arrisdrift. Impregnochelys pachytectis gen. et sp. nov . is described from Rusinga Island, Kenya, and is unique in having the anterior shell opening orientated ventrally and in having struts on the internal surface of the neurals, but shares with Kinixys a unique epiplastron shape, a high number of axillary scutes and unique orientation of the head of the femur.  相似文献   

7.
湖南等三地区东方田鼠遗传特性的分析比较   总被引:8,自引:2,他引:6  
用染色体G带核型分析、生化位点、随机扩增多态性DNA(RAPD)标记等方法,对湖南洞庭湖湖滨、宁夏青铜峡市农田和黑龙江伊春市金山屯草甸3个地区的东方田鼠遗传特性进行了分析。结果表明,湖南和宁夏地区东方田鼠染色体数均为2N=52,黑龙江东方田鼠染色体数则为2N=42;生化位点结果显示3个地区的东方田鼠均呈遗传非均一性;湖南、宁夏和黑龙江鼠的个体间RAPD遗传距离分别为0.244(0.143—0.353)、0.226(0.161—0.294)、0.541(0.357—0.692)。湖南和宁夏两地区鼠种群间的遗传距离为0.367,湖南和宁夏鼠杂交一代与其亲代的RAPD遗传距离在0.310以下;但黑龙江鼠与湖南和宁夏鼠种群问的遗传距离分别为0.619和0.633。总的表明,3个地区的东方田鼠均呈遗传非均一性,但湖南与宁夏鼠在染色体、生化位点和RAPD标记等方面都具有相似性,并可杂交,而黑龙江鼠与其它两地的鼠不能杂交,且黑龙江鼠在遗传特性方面与前二地鼠有很大差异,因而后的“种”级分类地位值得进一步研究。  相似文献   

8.
The study of prehistoric parasitism through analysis of coprolites, mummies, skeletons, and latrine soils is rapidly growing. Its development in North America is interdisciplinary and is derived from the fields of physical anthropology, parasitology, and archaeology. The various parasite finds from North America are reviewed. The data show that prehistoric peoples in North America suffered from a variety of parasitic diseases. The validity of the findings are then considered. Although most finds of parasites from prehistoric contexts result from human infections, some finds cannot be verified as such. However, in combination with data from South America, it is clear that prehistoric peoples in the Americas were host to a variety of human parasites, some of which were not previously thought to be present before historic times.  相似文献   

9.
云南元谋古猿地点的小哺乳动物化石   总被引:1,自引:1,他引:0  
本文依据元谋盆地西北小河村一带古猿化石地点所产6种小哺乳动物(Anourosorexsp.,Lepondaegen.etsp.indet.,Sciurotamiassp.,Monosaulaxsp.,Brachyrhizomysblacki,Rhizomyidaegen.etsp.indet),初步论证了几个合古猿化石地点(8603、8701、8704、8801、9001)的时代均为晚中新世,相当于欧洲Turolian晚期,比禄丰古猿化石地点的时代稍晚.  相似文献   

10.
Feeding dynamics in the spittlebug Philaenus spumarius were analysed to determine the food source. Evidence from previous reports indicates that this species and similar insects feed from the xylem. However, it is not clear whether they extract sap from the main transpiration stream, or from some subsidiary compartment of xylem, such as immature or cavitated vessels. In feeding from such subsidiary compartments, the insects could avoid the large hydraulic tensions thought to prevail in xylem on the main transpiration stream. Philaenus , for example, is shown here to initiate feeding, and to feed rapidly, from plants in which the full xylem tension is estimated at −10 bar. From measurements of feeding rates and feeding patterns in stressed and unstressed plants, it is shown that Philaenus cannot feed from subsidiary xylem compartments. It is concluded that this insect feeds directly from the main transpiration stream, and at the full hydraulic tension which prevails there. The anatomy of the feeding pump in Philaenus appears consistent with this conclusion. Spittlebugs therefore offer an experimental tool for quasi- non-invasive sampling of the transpiration stream.  相似文献   

11.
Vema levinae Warén, sp. n. is described from a submarine volcano off western Mexico. The type species of Rokopella and Veleropilina are redescribed, the usage of the names is discussed and Rokopella and Veleropilina are recognized as valid genera in Neopilinidae. Rokopella euglypta (Dautzenberg & Fischer, 1897) is redescribed from shells and a single live specimen taken from seamounts south of the Azores, from a depth of 1200–1600 m. Tectura reticulata Seguenza, 1876 (Gastropoda, 'Acmaeidae', southern Italy, Upper Pliocene/Lower Pleistocene) is considered to have been based on the monoplacophoran species previously known as Neopilina zografi from the Mediterranean, and is classified in the genus Veleropilina. Veleropilina zografi (Dautzenberg & Fischer, 1896) is redescribed based on shells from several seamounts south of the Azores. It is considered distinct from Rokopella euglypta and classified in the genus Veleropilina. An undescribed species of Veleropilina from a seamount off southern Baja California is reported, figured and discussed but not formally described.  相似文献   

12.
Production of ethylene by infected preclimacteric apple peel is much more sensitive to inhibition by acetate and potassium nitrate than is that from healthy climacteric peel. The opposite is true of the efrect of rhizobitoxine. It is suggested that the ethylene produced from the infected tissues originates from the host's metabolism rather than from that of the fungus, but by a pathway different from that operative in healthy climacteric peel.  相似文献   

13.
Brunke AJ  Majka CG 《ZooKeys》2010,(65):51-61
New distributional and bionomic data are provided for species of the genus Xantholinus in North America. Xantholinus elegans (Olivier 1795) (= X. jarrigei Coiffait 1956)is recorded from North America for the first time, based on specimens collected in Ontario, Canada from 2007-2010. The armature of the internal sac of the aedeagus in situ is illustrated to aid in identification. Xantholinus linearis (Olivier 1795), known previously from the Maritime Provinces of Canada and the eastern United States, is newly recorded from Ontario. Xantholinus longiventris Heer 1839 is still only known from western North America. A key is provided to allow recognition of all three species.  相似文献   

14.
比较研究几种兼性和专一性CAM植物材料的PEPC同工酶表明:经自然干旱诱导,兼性CAM植物露花(Mesembryanthemumcordifolium)、长药景天(Sudumspectabile)有新的PEPC同工酶的出现,诱导前后各同工酶的天然分子量变化不大;而土三七(Sedumaizoon)则没有新的PEPC同工酶出现,但诱导后其同工酶的天然分子量有所增大。以上几种兼性CAM植物的PEPC同工酶酶谱无明显昼夜变化。专一性CAM植物的PEPC酶谱和天然分子量均较一致,亦无昼夜差异。  相似文献   

15.
酶解法所获鳗骨油品质的研究   总被引:1,自引:0,他引:1  
对以酶解法工艺提取鳗骨油时,不同阶段所获油脂的品质进行了比较研究.结果表明这些油脂的品质存在显著的差异.酶解法获得品质较高的鳗骨油.交酯化和冬化分离处理可使酶解鳗骨油的不饱和度显著提高,而氧气存在时可导致POV值的大幅度增加.    相似文献   

16.
General practitioners in the vicinity of Lake Velencei in Fejér County, Hungary, have reported an unusual pattern of recent cancer mortality. Our aim was to clarify whether the presumed mortality cluster is epidemiologically justified; whether it is restricted to the locations in question or also appears elsewhere in the county; and if it is associated with some particular disease group. County mortality from malignancies of the digestive system, other malignancies, and all other causes for the period 1994 to 1999 was analyzed in 15- to 64-year-old men and women, using conventional standardized mortality ratios and empirical Bayes estimates. A continuous surface was interpolated from settlement level data for mortality maps. A mortality cluster from men's digestive cancers is apparent north and east of Lake Velencei and also elsewhere in the county. Differences from the country average in the frequency of males' deaths from other malignancies are fairly limited. A number of problematic areas in men's mortality from other causes are identifiable, including some of the settlements under the primary focus. Women's digestive tract cancer mortality in the area of the men's cluster near Lake Velencei is below the national average. There are almost no differences from the country level in women's deaths from other malignancies. Female mortality from all other causes shows remarkable elevations in the south of the county. Our results suggest the possible role of geographically localized exposures. Men's high mortality from digestive tract cancers is a problem affecting a considerable area of the county, necessitating further investigation. Continued search for causes is also warranted by some estimates of exceptionally high death rates in women from causes other than malignancies.  相似文献   

17.
Glycopeptides have been isolated from tryptic digests of kappa-type light chains separated from human myeloma proteins obtained from the serum of two patients, Car and Rai. The glycopeptides are derived from the variable region of the chain in both cases, but from different sections. On the basis of homology it is deduced that glycopeptide from Car, kappaI type, is derived from position 25-31 whereas that from Rai, kappaII type, is from position 62-77, their sequences being respectively Ala-Ser-Gln-Asn-Ile-Ser and Phe-Ser-Gly-Ser-Gly-Ser-Gly(Thr,Asp)Phe-Thr-Leu-Asx-Ile-Ser-Arg. The significance of the results is discussed in connexion with the nature of the attachment site of carbohydrate to protein.  相似文献   

18.
湖北铁线莲属的区系特征及地理分布   总被引:5,自引:0,他引:5  
在查阅文献和标本采集鉴定的基础上,确认湖北铁线莲属(Clematis L.)有37种14变种。对湖北铁线莲属的区系地理进行了分析。铁线莲属的分布中心在中国的亚热带地区,在中国范围内云南和四川分布的种类最多(包括变种),然后以此为中心向四周的分布逐渐减少。湖北铁线莲属大部分种类分布在鄂西山区。湖北铁线莲属的地理成分以中国特有分布为主,中国特有成分占湖北种类总数的68.6%。区系的性质是温带性的。根据毛茛科最原始的类群金莲花亚科Subfam.Helleboroideae起源中心的推测和铁线莲属古老类群的分布,推测铁线莲属起源于中国西南地区,并以此解释湖北铁线莲属区系和周围省份铁线莲属区系的关系。  相似文献   

19.
Ascorbate peroxidase is a hydrogen peroxide-scavenging enzyme that is specific to plants and algae and is indispensable to protect chloroplasts and other cell constituents from damage by hydrogen peroxide and hydroxyl radicals produced from it. In this review, first, the participation of ascorbate peroxidase in the scavenging of hydrogen peroxide in chloroplasts is briefly described. Subsequently, the phylogenic distribution of ascorbate peroxidase in relation to other hydrogen peroxide-scavenging peroxidases using glutathione, NADH and cytochrome c is summarized. Chloroplastic and cytosolic isozymes of ascorbate peroxidase have been found, and show some differences in enzymatic properties. The basic properties of ascorbate peroxidases, however, are very different from those of the guaiacol peroxidases so far isolated from plant tissues. Amino acid sequence and other molecular properties indicate that ascorbate peroxidase resembles cytochrome c peroxidase from fungi rather than guaiacol peroxidase from plants, and it is proposed that the plant and yeast hydrogen peroxide-scavenging peroxidases have the same ancestor.  相似文献   

20.
Phosphatidylcholine and choline homeostasis   总被引:3,自引:0,他引:3  
Phosphatidylcholine (PC) is made in mammalian cells from choline via the CDP-choline pathway. Animals obtain choline primarily from the diet or from the conversion of phosphatidylethanolamine (PE) to PC followed by catabolism to choline. The main fate of choline is the synthesis of PC. In addition, choline is oxidized to betaine in kidney and liver and converted to acetylcholine in the nervous system. Mice that lack choline kinase (CK) alpha die during embryogenesis, whereas mice that lack CKbeta unexpectedly develop muscular dystrophy. Mice that lack CTP:phosphocholine cytidylyltransferase (CT) alpha also die during early embryogenesis, whereas mice that lack CTbeta exhibit gonadal dysfunction. The cytidylyltransferase beta isoform also plays a role in the branching of axons of neurons. An alternative PC biosynthetic pathway in the liver uses phosphatidylethanolamine N-methyltransferase to catalyze the formation of PC from PE. Mice that lack the methyltransferase survive but die from steatohepatitis and liver failure when placed on a choline-deficient diet. Hence, choline is an essential nutrient. PC biosynthesis is required for normal very low density lipoprotein secretion from hepatocytes. Recent studies indicate that choline is recycled in the liver and redistributed from kidney, lung, and intestine to liver and brain when choline supply is attenuated.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号