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1.
The functional morphology of Levitusia , based principally upon the type-species L. humerosa (J. Sowerby), is described and compared with living brachiopods. It is concluded that Levitusia species lived in tropical Dinantian seas with agitated waters and at shallow depths, perhaps no more than 50 m. The lithologies in which specimens are found support this view and indicate the need for some revision in our interpretations of some Dinantian sedimentary environments. Further evidence for the synonymy of L. christiani (de Koninck) in L. humerosa is presented.  相似文献   

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3.
Trunk woods of Early Carboniferous Protopitys buchiana show the earliest example of tylose formation and the first record for a progymnosperm. Protopitys tyloses are more densely located in inner trunk woods and near growth layer boundaries. We suggest, therefore, that an altered physiological state of living ray cells, during dormancy and/or following water stress, was necessary to make the woods vulnerable to tylose formation. Coupled with the distribution and proximity of abundant wood ray parenchyma to large xylem conducting cells, the positions of conduits filled with tyloses can be interpreted as ecophysiological responses of the plant to changes in local environment. In addition, some xylem conducting cells might have functioned as vessels. Fungal hyphae are present in some tracheary cells and in some areas with tyloses, but there is no evidence for wood trauma; we conclude, therefore, that these particular cases of tyloses are probably not induced by wound trauma. Protopitys buchiana wood thus shows structure/function similarities to modern woods with vessels, such as those of dicot angiosperms. This implies that ancient and modern plant ecophysiological responses correlate well with the physical parameters of their cellular construction.  相似文献   

4.
中国新纪录属--长角斑蚜属研究(同翅目:蚜科:角斑蚜亚科)   总被引:4,自引:4,他引:0  
研究了中国蚜科Aphididae角斑蚜亚科Calaphidinae 1新纪录属-长角斑蚜属Calaphis Walsh,1863,记述2新纪录种,居桦长角斑蚜Calaphis betulicola(Kaltenbach,1843)和相似长角斑蚜Calaphis similis Quednau,1979。编制中国长角斑蚜属分种检索表,每种提供形态记述、寄主植物、分布及形态特征图。研究标本保存在中国科学院动物研究所动物标本馆。  相似文献   

5.
Calmodulin-dependent protein kinase II (CaMKII) is known to play a key role during induction of long-term potentiation (LTP). Given the dependence of LTP on the frequency of synaptic activation, several previous modeling efforts have proposed that biochemical properties of CaMKII itself might be in part responsible for this dependence. Recently, De Koninck and Schulman (1998) have provided direct experimental evidence that the enzyme itself is sensitive to the frequency of Ca2+ activation. Here we demonstrate the ability of a detailed biophysical model constructed solely on enzyme kinetics of purified proteins to generate the frequency sensitivity demonstrated by De Koninck and Schulman. Quantitative analysis of the model reveals that this frequency sensitivity is provided by a mechanism different from those previously postulated. This analysis leads to specific predictions concerning the effects of mutations on this process. We further employ the model to examine the asymptotic behavior of CaMKII-phosphatase system during longer simulated periods of stimulation. The analyses of the model suggest that the transient and asymptotic frequency sensitivity of this enzyme are dependent on different biochemical mechanisms. These results may be applicable to Ca2+/calmodulin signaling pathways in general.  相似文献   

6.
We analysed the length‐weight relations (LWRs) of 10 fish species inhabiting different habitats from Visakhapatnam, Coast of India. Samples were obtained between August 2013 and December 2016 from commercial trawlers at the local fish landing centre (16.98°N–20.20°N, Long.82.19°–86.53°E). Fishes were captured between 100 and 300 m depth with demersal trawl net (head rope length: 46 m and cod end mesh size: 40 mm with a 38 m high speed. Total length (TL; nearest to 0.1 cm) and body weights (nearest to 0.1 g) were taken from each individual. This study provides new maximum length data for two species (Archamia bleekeri (Günther, 1859) and Ostorhinchus fleurieu (Lacepède, 1802), and LWR estimates for rare deep reef associated fishes are provided for the first time. All LWRs were significant with r2 values ranging from .908 for Sargocentron praslin (Lacepède, 1802) to .981 for Parapercis pulchella (Temminck & Schlegel, 1843) and “b” values ranged from 2.5216 for Parapercis pulchella (Temminck & Schlegel, 1843) to 3.4746 for Ostorhinchus fleurieu Lacepède, 1802.  相似文献   

7.
《Comptes Rendus Palevol》2002,1(7):555-564
The main publications on Cretaceous Bivalves of Alcide d’Orbigny are the Paléontologie française – Terrains crétacés. III. Lamellibranches (1843–1847) and the Prodrome de stratigraphie universelle, vol. II (1850). The importance and influence of these publications for today’s taxonomic palaeontology are discussed. It is shown that the Paléontologie française continues to be one of the major 19th-century papers but that the Prodrome is only rarely referred to.  相似文献   

8.
Length–weight and length–length relationships are presented for four freshwater fish species [Liza abu (Heckel, 1843), Aphanius mento (Heckel, 1843), Oxynoemacheilus hamwii (Krupp & Schneider, 1991) and Chondrostoma kinzelbachi Krupp, 1985] captured in Gölba?? Lake, Hatay, Anatolia. No information regarding length–weight relationships was reported previously in FishBase for C. kinzelbachi, A. mento and O. hamwii. Specimens were obtained from January to May 2012 using electrofishing and cast nets. This study presents the first study on LWR data for C. kinzelbachi, A. mento and O. hamwii.  相似文献   

9.
Carnation cuttings treated with non-transformed and 1-aminocyclopropane (ACC) deaminase-containing Azospirillum brasilense Cd1843 produced significantly more roots than untreated controls and fewer roots than cuttings treated with 0.1% indolebutyric acid (IBA). The roots produced by cuttings treated with ACC deaminase-containing Azospirillum brasilense Cd1843 were the longest roots resulting from any of the treatments, followed by non-transformed Azospirillum brasilense Cd1843, 0.1% IBA, and treatment with water. The results are interpreted in terms of a previously proposed model of bacterial promotion of plant growth by ACC deaminase and indoleacetic acid, and may have implications for the use of plant growth-promoting bacteria in the flower industry.  相似文献   

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We have studied the molecular basis for the resistance of human CEM leukemia cells to GW1843, a thymidylate synthase inhibitor. GW1843-resistant cells displayed a approximately 100-fold resistance to GW1843 and methotrexate but were collaterally sensitive to the lipophilic antifolates trimetrexate and AG337, which enter cells by diffusion. These cells exhibited a 12-fold decreased methotrexate influx but surprisingly had a 2-fold decreased folic acid growth requirement. This was associated with a 4-fold increased influx of folic acid, a 3.5-fold increased steady-state level of folic acid, and a 2.3-fold expansion of the cellular folate pool. Characterization of the transport kinetic properties revealed that GW1843-resistant cells had the following alterations: (a) 11-fold decreased transport K(m) for folic acid; (b) 6-fold increased transport K(m) for GW1843; and (c) a slightly increased transport V(max) for folic acid. Sequence analysis showed that GW1843-resistant cells contained the mutations Val-29 --> Leu, Glu-45 --> Lys, and Ser-46 --> Ile in the first transmembrane domain of the reduced folate carrier. Transfection of the mutant-reduced folate carrier cDNA into methotrexate transport null cells conferred resistance to GW1843. This is the first demonstration of multiple mutations in a confined region of the human reduced folate carrier in an antifolate-resistant mutant. We conclude that certain amino acid residues in the first transmembrane domain play a key role in (anti)folate binding and in the conferring of drug resistance.  相似文献   

12.
There are over 10,000 species of venomous marine molluscs, the vast majority of these, which are generally referred to as "turrids", are traditionally assigned to a single family, Turridae (Powell 1966). Here, we provide an initial molecular analysis of the type genus of the family, Turris R?ding, 1798, thought to be among the most well characterized groups in the family. We show that the type genus is not monophyletic. We analyzed specimens conventionally assigned to 9 different Turris species using molecular markers, combined with the shell morphology and radular anatomy whenever feasible. The results suggest that species assigned to the genus Turris, provisionally assigned to two different subgenera are not monophyletic. Five previously described species belong to the subgenus Turris (s.s.) R?ding 1798: Turris babylonia, (Linne, 1758), Turris grandis, (J. E. Gray, 1834), Turris dollyae, (Olivera, 1999), Turris normandavidsoni (Olivera, 1999) and Turris spectabilis (Reeve, 1843). With a change in species designation, Turris assyria (formerly T. babylonia1010) is added to a well-defined clade, which is in turn more closely related to Lophiotoma and Gemmula species than to the other five Turris species. We show that these five species conventionally assigned to Turris do not belong in the same subgenus, and form a clade provisionally designated as AnnulaturrisPowell, 1966: Turris annulata, (Reeve, 1843), Turris undosa, (Lamarck, 1816), Turris cristata, (Vera-Peláez, Vega-Luz, and Lozano-Francisco 2000) Turris cryptorrhaphe (G. B. Sowerby, 1825) and Turris nadaensis (Azuma, 1973). Implications of the molecular phylogenetic results and its correlation with radular morphology are discussed.  相似文献   

13.
A study of the inheritance of malignant hyperthermia (MH) in the British Landrace breed revealed the same substitution of T for C at nucleotide 1843 in the ryanodine receptor (RYR1) gene that was previously shown to be correlated with MG in five Canadian swine breeds. Cosegregation of the mutation with MH in 338 informative meioses led to a lod score of 101.75 for linkage at Omax = 0.0. The substitution was also associated with a HinPI- BanII+ RsaI- haplotype in this breed, as in the five breeds tested earlier, suggesting its origin in a common founder animal. DNA-based detection of the MH status in 376 MH-susceptible heterozygous (N/n) and homozygous (n/n) pigs was shown to be accurate, eliminating the 5% diagnostic error that is associated with the halothane challenge test and flanking marker haplotyping procedures in current diagnostic use. These results strongly support the view that the substitution of T for C at nucleotide 1843 is the causative mutation in porcine MH and demonstrate the feasibility of rapid, accurate, noninvasive, large-scale testing for porcine MH status using DNA-based tests for the mutation.  相似文献   

14.
Keys in Spanish and English are given for the genera of Chrysomelinae known from Costa Rica. For each genus, a list of species compiled from collections in the University of Costa Rica, the National Biodiversity Institute, and the entomological literature is presented. The genus Planagetes Chevrolat 1843 is recorded for the first time from Central America, and the genus Leptinotarsa St?l 1858 is synonymized with Stilodes Chevrolat 1843.  相似文献   

15.
Length–weight relationships (LWR) are presented for five commercial freshwater fish species (Luciobarbus esocinus, Heckel, 1843; Capoeta trutta, Heckel, 1843; Barbus lacerta, Heckel, 1843; Luciobarbus mystaceus, Pallas, 1814 and Capoeta umbla, Heckel, 1843) collected from Keban Dam Lake located in eastern Anatolia, Turkey. Studied samples were obtained between July and December 2008 using commercial gill nets. For each species the sample size, length range, weight range, length‐weight relationships, 95% confidence intervals of a and b, coefficient of correlation and growth type are given. Values of b were between 2.915 (Luciobarbus esocinus) and 3.079 (Copoeta trutta) and r2 values from 0.919 (Copoeta trutta) to 0.987 (Barbus lacerta) in the study. New maximum length and length–weight relationships are reported for Barbus lacerta and Luciobarbus mystaceus.  相似文献   

16.
A review of the subgenus Metaphyllobius Smirnov of the weevil genus Phyllobius Germ. is given. The name Ph. maculatus Tournier, 1880 is restored from synonymy with Ph. pomaceus fessus Boheman, 1843. A new synonymy is established: Ph. maculatus Tournier, 1880 (= jacobsoni Smirnov, 1913, syn. n.). Ph. fessus Boheman, 1843 is downgraded to a subspecies of Ph. pomaceus Gyllenhal, 1834—Ph. pomaceus fessus Boheman, 1843, stat. n. Data on the distribution and hosts of, and a key to European and Siberian species of the subgenus Metaphyllobius are given.  相似文献   

17.
This study describes the length–weight and length–length relationships for three cyprinid species from the Bibi‐Sayyedan River (western Isfahan provinces, Iran). The slope parameter (b) values in the length–weight relationship equations were determined as 3.0729 for Alburnus mossulensis Heckel, 1843; 2.8509 for Barbus lacerta Heckel, 1843; and 3.0864 for Chondrostoma regium (Heckel, 1843). This study presents the first LWR and LLR references for these species in the Bibi‐Sayyedan River.  相似文献   

18.
A toxin-antitoxin system, vp1842/vp1843, locates within a superintegron on the Vibrio parahaemolyticus genome chromosome I whose toxin gene vp1843 encodes a DNA nicking endonuclease. We found that the vp1843 expression in Escherichia coli cells strongly induced chromosomal DNA degradation. On the basis of these observations, we discuss a possible physiological role of vp1842/vp1843 in V. parahaemolyticus.  相似文献   

19.
Leading Moravian sheep breeders, who joined with university professors and other educated citizens to form a Sheep Breeders' Society in 1814, looked to science to provide a reliable basis for breeding. Their activities reached a climax in the 1830s, when they defined and focused on heredity as the central research goal. Among the members taking part was Abbot Cyrill F Napp, who in 1843 would accept Mendel into the monastery. The contributions of Abbot Napp to the sheep breeders' view of heredity are here described. After 1900, when Moravian animal breeding sought to embrace Mendelism, in competition with other theories, a major influence was exerted by Jaroslav Krízenecky (1896-1964). In 1963, Krízenecky accepted responsibility for establishing the Mendel Museum (Mendelianum) in Brno as a vehicle for historical research into the origin and essence of Mendel's discovery.  相似文献   

20.
The Candida albicans adhesin, Als3p, was identified as a potential cognate antigen for previously described human antibody fragments [single-chain variable fragment (scFv)] based on similarity of the binding pattern of the scFv to the distribution of this protein on the hyphal surface. Although all scFv bound avidly to wild type, scFv3 showed no detectable binding via immunofluorescence assay to strain 1843, containing a homozygous deletion of ALS3. Binding to the ALS3 reintegrant strain, 2322, was preserved, and scFv3 also bound to Saccharomyces cerevisiae expressing ALS3. Other scFv retained binding to 1843, but with a markedly altered pattern. To determine if scFv3 could interfere with Als3p function, adhesion assays were conducted using human epithelial or endothelial cells as target. Treatment of wild-type C. albicans with scFv3 reduced adhesion of the fungus to both cell types to levels comparable to the als3Delta/als3Delta mutant. These experiments confirm that phage display is a viable method to isolate human scFv specific to an antigen implicated in C. albicans virulence, and that the scFv interfere with adhesion to human cells. The altered pattern of immunostaining with other scFv that retain binding to the als3Delta/als3Delta mutant suggest that Als3p may also have a role in structural organization of the C. albicans cell surface.  相似文献   

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