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 31 毫秒
1.
Eight aeolid opisthobranch molluscs of the subfamilies Facelininae, Favorininae, and Herviellinae are reported from Tanzanian waters, and two species from Northwestern India. New records from Queensland, Australia greatly extend the range of two species reported from Tanzania. Phidiana militaris (Alder & Hancock) and P. indica (Bergh) are shown to be distinct and a species from New Zealand, originally identified as P. militaris , is shown to be new. P. bourailli (Risbec), previously reported only from New Caledonia, is described from Tanzania, as is a new species of Phidiana. Favorinus japonicus Baba is reported from Tanzania, the first published record outside Japan, a new species of Godiva is described from Tanzania and Queensland, and three new species of Sakuraeolis are described, one from India and two from Tanzania. A new species of Herviella is described from Tanzania.  相似文献   

2.
Spectral properties of solutions containing mixtures of chlorophyll a and chlorophyll c are investigated. The yield of excitation energy migration from chlorophyll c to chlorophyll a is obtained ranging from 23 to 48% dependent on the used dye concentrations. The back transfer from chlorophyll a to chlorophyll c is negligible. The shape of the polarization excitation spectrum of chlorophyll c in the Soret band region is less composed than that of chlorophyll a. Depolarization of chlorophyll a fluorescence by chlorophyll c is in agreement with the conclusion drawn from fluorescence quenching that excitation energy migrates from chlorophyll c to chlorophyll a.  相似文献   

3.
Rhopalotrema n. g. is erected to accommodate two new species of didymozoid collected from platycephalid fishes from South-east Queensland, Australia and is assigned to the subfamily Didymozoinae. Rhopalotrema elusiva n. sp. is described from the fins of Platycephalus fuscus and R. pterygionastes n. sp. is described from the fins of P. indicus. The new genus is similar to Neometadidymozoon, but is distinguished from it by the structure of the testes, which are convoluted and extend from near the anterior end of the hindbody to a point only a short distance into the forebody. The two new species are distinguished from each other by their size and the size and shape of the oral sucker and pharynx.  相似文献   

4.
The illness-death model is the simplest multistate model where the transition from the initial state 0 to the absorbing state 2 may involve an intermediate state 1 (e.g., disease relapse). The impact of the transition into state 1 on the subsequent transition hazard to state 2 enables insight to be gained into the disease evolution. The standard approach of analysis is modeling the transition hazards from 0 to 2 and from 1 to 2, including time to illness as a time-varying covariate and measuring time from origin even after transition into state 1. The hazard from 1 to 2 can be also modeled separately using only patients in state 1, measuring time from illness and including time to illness as a fixed covariate. A recently proposed approach is a model where time after the transition into state 1 is measured in both scales and time to illness is included as a time-varying covariate. Another possibility is a model where time after transition into state 1 is measured only from illness and time to illness is included as a fixed covariate. Through theoretical reasoning and simulation protocols, we discuss the use of these models and we develop a practical strategy aiming to (a) validate the properties of the illness-death process, (b) estimate the impact of time to illness on the hazard from state 1 to 2, and (c) quantify the impact that the transition into state 1 has on the hazard of the absorbing state. The strategy is also applied to a literature dataset on diabetes.  相似文献   

5.
Abstract:  The holotype of Dollosuchus dixoni (Owen) from the Early–Middle Eocene Bracklesham Beds of England is a set of mandibular fragments that cannot be distinguished from corresponding parts of other longirostrine crocodylians. An isolated humerus from the Bracklesham Beds is consistent with a gavialoid, but it cannot be referred to the holotype of D. dixoni . The name Dollosuchoides densmorei is established for the well-preserved skull and skeleton of a tomistomine from the Middle Eocene of Belgium that had been referred to D. dixoni . It can be clearly distinguished from the basal tomistomine ' Crocodilus ' spenceri Buckland from the Lower Eocene of England, which cannot be referred to Dollosuchoides and is provisionally referred to Kentisuchus Mook. Although basal within Tomistominae, Dollosuchoides is more closely related to Tomistoma than to Kentisuchus .  相似文献   

6.
Jugubracon gen. n (type species: Jugubracon ferrugineus sp.n.) from New Guinea is described and illustrated. Jugubracon is related to Bracon , from which it is distinguished by a mid-longitudinally carinate 1st metasomal tergite and a curved fore-wing vein 1-SR+M. Kimavu gen.n. (type species: Kimavu fulvus sp.n.) from Sierra Leone, South Africa and Madagascar is described and illustrated. Kimavu is related to Cratocnema Szépligeti, from which it is distinguished by having long antennae which, in females, have a pale coloured annulus. Brucon annulicornis Brues, 1924, is transferred to Kimavu. Mollibracon gen.n. (type species: Bracon bimaris Turner, 1918) from Australia is described and illustrated. Mollibracon is related to Myosoma Brullé, from which it is distinguished by a strongly curved fore-wing vein 1-SR+M.  相似文献   

7.
ELIASSON, U. H. 1985. Identity and taxonomic affinity of some members of the Amaranthaceae from the Galápagos Islands. The type species of Pleuropetalum, P. DarwiniI, is endemic to the Galápagos and is morphologically closer to P. pleiogynum than to P. sprucei. Pleuropetalum pleiogynum has a wider distribution than previously assumed, ranging from Costa Rica to Peru. Amaranlhus anderssonii is closely related to A. urceolatus, a species of the Pacific coast of S America, and to A. berlandieri, a species of Texas and NE Mexico. Amaranlhus squamulatus, previously regarded as endemic to the Galápagos, is reported from the Guayas province of Ecuador. The genus Galápagosus, proposed for Amaranlhus sclerantoides, is rejected. Lithophila scirpoides, an overlooked taxon from the Galápagos, is believed to be an aberrant specimen of L. radicala. Lithophila subscaposa from the islands of Santiago and Pinzon differs morphologically from the specimens of Floreana. Iresine edmonstonii, probably erroneously reported from the Galápagos, is conspecific with J. angusti/olia. Blutaparon rigidum is morphologically divergent from other members of the genus, being adapted to arid conditions, and is assumed to be extinct.  相似文献   

8.
Two new species of strongyloid nematodes are described from tree-kangaroos, Dendrolagus spp. (Marsupialia: Macropodidae), from Irian Jaya, Indonesia. Macropostrongyloides dendrolagi n. sp. from the colon of Dendrolagus dorianus (type-host) and D. mbaiso is distinguished from congeners by the presence of a cephalic inflation and paired lateral alae which extend along the body from the cephalic inflation. Mbaisonema coronatum n. g., n. sp., from the stomach of D. mbaiso, is allocated to the tribe Coronostrongylinea Beveridge, 1986, as the buccal capsule is reduced to a sclerotised annulus and the lining is inflated into lip-like lobes at the anterior extremity. The new genus is allied to Popovastrongylus Mawson, 1977, from which it is distinguished by the presence of a labial crown composed of numerous elements.  相似文献   

9.
The cranial capacity of Olduvai Hominid 7 is estimated to be 690 cc, with a standard uncertainty range of 538 to 868 cc. The estimate is derived from a systematic consideration of the relationships between Bregma-Asterion chords and cranial capacities obtained from a large sample of Homo sapiens and Pan troglodytes and from available fossil hominids. The estimation technique is applicable to other characters and specimens.  相似文献   

10.
Ascaridoid nematodes occurring in South American mammals are divided into categories based on their possible origin. The affinities are discussed of five species so far known only from the Neotropical Region. Toxocara alienata (Rudolphi 1819) is reported from Nasua rufa socialis, Procyon cancrivorus, and Tayassus torquatus. The specimens from T. torquatus are described and found most closely to resemble Toxocara mackerrasae from south-east Asian and Austrialian rodents. Anisakis insignis from Inia geoffrensis is transferred back to Peritrachelius Diesing, 1851, on account of the structure of the lips and spicules. P. insignis is shown to exhibit remarkable convergence of lip structure with Lagochilascaris turgida from Didelphis marsupialis. Galeiceps longispiculum (Freitas & Lent, 1941) from Pteronura brasiliensis is confirmed as a species distinct from G. cucullus (Linstow, 1899) and G. spinicollis (Baylis, 1923), but G. simiae (Mosgovoy, 1951) is considered to be a synonym of G. spinicollis. An error in the host record of G. spinicollis is corrected from Cercopithecus leucampyx kandti to Lutra maculicollis kivuana. Ascaris dasypodina Baylis, 1922 from armadillos, including Cabassous unicinctus and Tolypeutes matacos, is redescribed and placed in a new genus Bairdascaris. The question is raised as to whether some species in Lagochilascaris, Galeiceps, and Toxocara may have crossed directly by sea from Africa to South America, rather than entering via North America.  相似文献   

11.
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   

12.
In genetic studies the haplotype structure of the regarded population is expected to carry important information. Experimental methods to derive haplotypes, however, are expensive and none of them has yet become standard methodology. On the other hand, maximum likelihood haplotype estimation from unphased individual genotypes may incur inaccuracies. We therefore investigated the relative efficiency of haplotype frequency estimation when nuclear family information is included compared to estimation from experimentally derived haplotypes. Efficiency was measured in terms of variance ratios of the estimates. The variances were derived from the binomial distribution for experimentally derived haplotypes, and from the Fisher information matrix corresponding to the general likelihood function of the haplotype frequency parameters, including family information. We subsequently compared these variance ratios to the variance ratios for the case of estimation from individual genotypes. We found that the information gained from a single child compensates missing phase information to a high degree, resulting in estimates almost as reliable as those derived from observed haplotypes. Thus, if children have already been genotyped for other reasons, it is highly recommendable to include them into the estimation. If child information is not already present, it depends on the number of loci and the haplotype diversity if it is useful to genotype a single child just to reduce phase ambiguity. In general, if the number of loci is less than or equal to three or if the number of haplotypes with a frequency >5% is less than or equal to four, haplotype estimation from individuals is quite good already and the improvement gained from a single child can not compensate the genotyping effort for it. On the other hand, under scenarios with many loci and high haplotype diversity, haplotype frequency estimation from trios can be more efficient than haplotype frequency estimation from individuals also on a per genotype base.  相似文献   

13.
A general method for the selective isolation of free and blocked amino-terminal peptides from proteins is described. The rationale behind the methodology is based on the reasoning that if a protein, which has all its free amino groups blocked by citraconylation, is digested with a protease, all peptides, except those derived from the amino terminus, will have a free amino group. Reaction of such a digest with 1-fluoro-2,4-dinitrobenzene (Dnp-F) followed by removal of citraconyl groups by acid treatment and removal of dinitrophenyl (Dnp) groups from histidine and tyrosine side chains by thiolysis will result in dinitrophenylation of all alpha-amino groups of peptides generated from internal cleavages, leaving only peptides derived from the amino terminus without a Dnp group. The strong adsorption of Dnp groups to polystyrene is used to selectively elute the underivatized amino-terminal peptides from such a column. It is also demonstrated how selective isolation of amino-terminal peptides can be used to determine whether a protein has a free or blocked amino terminus.  相似文献   

14.
Sec12p is an integral membrane protein required in vivo and in vitro for the formation of transport vesicles generated from the ER. Vesicle budding and protein transport from ER membranes containing normal levels of Sec12p is inhibited in vitro by addition of microsomes isolated from a Sec12p-overproducing strain. Inhibition is attributable to titration of a limiting cytosolic protein. This limitation is overcome by addition of a highly enriched fraction of soluble Sar1p, a small GTP-binding protein, shown previously to be essential for protein transport from the ER and whose gene has been shown to interact genetically with sec12. Furthermore, Sar1p binding to isolated membranes is enhanced at elevated levels of Sec12p. Sar1p-Sec12p interaction may regulate the initiation of vesicle budding from the ER.  相似文献   

15.
The effect of age on protein synthesis in mouse liver   总被引:3,自引:3,他引:0       下载免费PDF全文
1. A system of microsomes and 105000g supernatant from livers of old mice is less able to promote the incorporation of [(14)C]phenylalanine into protein than a similar system from livers of young animals. 2. The decrease in [(14)C]phenylalanine incorporation is attributable to changes in microsomes from old animals rather than in the cell-sap fraction. 3. Decreased synthetic ability is found in various classes of microsomes from older animals, namely unfractionated, light and heavy microsomes, but not in detergent-washed ribonucleoprotein particles. 4. Deletions of certain detergent-soluble microsomal proteins accompany the decreased synthetic ability of microsomes from older animals. 5. Microsomes from old mice are less responsive to a synthetic messenger RNA, polyuridylic acid, and this is partly due to a higher rate of hydrolysis in the presence of cell sap from animals of extreme age. 6. Other more direct evidence, from the priming of a cell-free protein-synthesizing system from bacteria and the examination of ribonucleoprotein particles on sucrose density gradients, suggests that senescence is accompanied by a decrease in messenger RNA content.  相似文献   

16.
The location measure of a residue in a globular protein is defined as the number of C alpha atoms surrounding the residue located within a sphere of the radius of 14 A. This quantity is a measure of the exposure of a residue to solvent, and is related closely to the distance from the center of mass of a protein. In this work, the experimental value for each residue of a protein is obtained from the X-ray crystallographic data, and the quantity is also calculated from the amino acid sequence data by applying an empirical parameter set to it. The correlation between the experimental and computed quantities is as high as 0.50 on the average over 92 proteins of known three-dimensional structure. Therefore, the location measure of every residue in a globular protein is predictable with good accuracy from the sequence.  相似文献   

17.
Alex Richman  Richard Orlaw 《CMAJ》1965,93(26):1336-1339
Changes in Canadian rates of mortality from barbiturates are examined, and their relation to barbiturate use in the general population is discussed. While the number of deaths attributed to barbiturates quadrupled, from 63 in 1950 to 232 in 1963, there has been a concomitant decrease in the number of deaths from inhalation of utility gas.Combined rates for deaths from utility gas and barbiturates declined steadily for most age groups between 1950-52, 1955-57, and 1959-63. It is possible that the increased mortality from barbiturates represents a change in fashion in regard to method of suicide. Changed mortality from barbiturates is not a valid measure of the extent to which consumption of barbiturates has increased in the Canadian population.  相似文献   

18.
1. Twenty minutes after injection of [(3)H]orotic acid into rats the rapidly labelled RNA from the liver is mainly associated with the nuclear fraction and little with the ribosomal cytoplasmic fraction. 2. The thermal denaturation of RNA from the fractions was not as reversible as that of the RNA extracted from whole liver. 3. Rapidly labelled RNA is synthesized by cells from a transplantable hepatoma when incubated in the presence of [(3)H]uridine and, after extraction and centrifugation, the label is present in three main fractions: one which sediments to the bottom of a gradient and is associated with DNA, a second which sediments to the heavy side of the 28s RNA, and a third which has a peak of activity between 28s RNA and 18s RNA and is associated with DNA. 4. After labelling and extraction of the RNA from Ehrlich ascites cells the distribution of radioactive components is similar to that of the material from the hepatoma cells. 5. The difference between the tumour cells and liver is due to some extent to the method of homogenizing the tissues and the nature of the components is discussed.  相似文献   

19.
Five new species of Fissistigma are described from Borneo. Fissistigma brevistipitatum sp. nov. is a species of lowland and hill forest mostly recorded from Sabah. Fissistigma bygravei sp. nov. is similar to F. hypoglaucum (Miq.) Merr. of the Malay Peninsula and Sumatra. Fissistigma carrii sp. nov. is from Mount Kinabalu. Fissistigma crassicaule is a robust plant known from a couple of collections from Sarawak. Fissistigma montanum sp. nov. is a species from hill and montane forest recorded from Brunei, Sabah and Sarawak. A new combination in Fissistigma is made for Melodorum multivenium Diels. Two recently described species of Fissistigma from Borneo ( F. cordifolium Irawan and F. magnisepalum Irawan) are reduced to synonymy of Friesodielsia excisa (Miq.) Steenis and Friesodielsia affinis (Hook. f. & Thomson) D. Das, respectively. Both species of Friesodielsia are lectotypified.  相似文献   

20.
The ciliated protozoan parasite Cryptocaryon irritans infecting marine fishes in Taiwan is described. Developmental characteristics and sequences of the ribosomal DNA regions such as part of 18 S, the entire first internal transcribed spacer, and part of 5.8 S of various Taiwan isolates of C. irritans were investigated. A total of 5 isolates was obtained from different fish-host species and localities, the majority from cultured fish species. C. irritans from Taiwan is able to shift its developmental characteristics, i.e. from non-adherent to adherent tomonts, from individualistic to aggregate-forming tomonts, from infection of the gills only to infection of the gills and body. Thus, it is not possible to classify strains of C. irritans on the basis of these parameters. Premature tomonts that developed from dead fishes were able to produce theronts that could infect fish host. Isolates from Pingtung and the USA had identical nucleotide sequences while an isolate from Malaysia was identical to an Israel isolate. Percentage variation among pairs of Taiwan isolates showed a higher degree of variation than isolate sequences listed in GenBank. Sequence analysis revealed highly aberrant isolates in Taiwan, and a phylogenetic tree distinguished a marine and a low-salinity variant. C. irritans from marine fishes in Taiwan, therefore, display some characteristics not previously reported. Since manipulation of salinity in brackishwater ponds and marine cage sites is not feasible, there is a need to develop new strategies for the control and prevention of cryptocaryoniasis.  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