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.
2.
Spodoptera frugiperda (J. E. Smith) is a highly adaptable polyphagous migratory pest in tropical and subtropical regions. Small heat shock proteins (sHsps) are molecular chaperones that play important roles in the adaptation to various environment stressors. The present study aimed to clarify the response mechanisms of S. frugiperda to various environmental stressors. We obtained five S. furcifera sHsp genes (SfsHsp21.3, SfsHsp20, SfsHsp20.1, SfsHsp19.3, and SfsHsp29) via cloning. The putative proteins encoded by these genes contained a typical α-crystallin domain. The expression patterns of these genes during different developmental stages, in various tissues of male and female adults, as well as in response to extreme temperatures and UV-A stress were studied via real-time quantitative polymerase chain reaction. The results showed that the expression levels of all five SfsHsp genes differed among the developmental stages as well as among the different tissues of male and female adults. The expression levels of most SfsHsp genes under extreme temperatures and UV-A-induced stress were significantly upregulated in both male and female adults. In contrast, those of SfsHsp20.1 and SfsHsp19.3 were significantly downregulated under cold stress in male adults. Therefore, the different SfsHsp genes of S. frugiperda play unique regulatory roles during development as well as in response to various environmental stressors.  相似文献   

3.
The structure and morphogenesis of rhabdites as well as morphology of pharynx walls in Bothrioplana semperi (Turbellaria, Bothrioplanidae) have been described. The ultrastructure of rhabdites and their morphogenesis in this species resemble those in Macrostomida (Turbellaria, Archoophora). The relative position of muscle layers in the pharynx walls draws Bothrioplana semperi closer to Tricladida maricola and some Tricladida paludicola and terricola. The analysis of ultrastructural and morphological characters in Bothrioplana semperi as compared to those in Turbellaria proseriata and tricladida is provided. It is shown that the apomophous to plesiomorphous characters ratio in the taxa analyzed argues most for the hypothesis of an early branching of these groups and the early Turbellaria neoophora as a whole. If this is the case, Proseriata and Tricladida are not sister groups, while Bothrioplanidae should be regarded as a sister group to the ancestors of Tricladida and, possibly, Neodermata.  相似文献   

4.
The host specificity of the gram-negative exoparasitic predatory bacterium Micavibrio aeruginosavorus was examined. M. aeruginosavorus preyed on Pseudomonas aeruginosa, as previously reported, as well as Burkholderia cepacia, Klebsiella pneumoniae, and numerous clinical isolates of these species. In a static assay, a reduction in biofilm biomass was observed as early as 3 hours after exposure to M. aeruginosavorus, and an ~100-fold reduction in biofilm cell viability was detected following a 24-h exposure to the predator. We observed that an initial titer of Micavibrio as low as 10 PFU/well or a time of exposure to the predator as short as 30 min was sufficient to reduce a P. aeruginosa biofilm. The ability of Micavibrio to reduce an existing biofilm was confirmed by scanning electron microscopy. In static and flow cell experiments, M. aeruginosavorus was able to modify the overall P. aeruginosa biofilm structure and markedly decreased the viability of P. aeruginosa. The altered biofilm structure was likely caused by an increase in cell-cell interactions brought about by the presence of the predator or active predation. We also conducted a screen to identify genes important for P. aeruginosa-Micavibrio interaction, but no candidates were isolated among the ~10,000 mutants tested.  相似文献   

5.
6.
Globally, the commercialisation of plants as observed in their uses by many industries such as the cosmeceutical, nutraceutical and pharmaceutical ones is gaining more interest and popularity. Mondia whitei is a popular medicinal plant which is endemic to Africa. Since antiquity, M. whitei has been used by African people to treat various ailments. The roots were used for the treatment of anorexia, stress, bilharzia and sexual dysfunction as well as for general aches and pains. Researchers have evaluated the efficacy of most of these claims by screening the M. whitei for biological activities such as antimicrobial, anti-inflammatory and anthelmintic as well as aphrodisiac efficacy. Furthermore, M. whitei has horticultural, nutritional and other socio-cultural values as reported in countries such as South Africa, Nigeria, Zimbabwe, Kenya, Uganda and Malawi. As a result of its numerous uses across the African continent, we attempt to explore and assess the economic potential of M. whitei with emphasis on medicinal values. The root of M. whitei is the most popular organ used in traditional medicine; consequently, this has resulted in the species becoming rare or threatened with extinction in the wild. Several authors have suggested solutions such as plant or plant part substitution to overcome the over-harvesting problem. The application of biotechnology techniques such as micropropagation and hairy roots also remain viable options which are presently being utilised to a lesser extent. Nevertheless, the sustainable harvesting and feasible conservation strategy for the species remains a major challenge. It is strongly recommended that in as much as the economic potential of M. whitei should be exploited, more detailed attention and studies should be geared towards its conservation. In order to ensure sustainable use and to derive maximum economic benefits, it is necessary to have empirical information detailing its ethno-botanical values, conservation status and commercial potential.  相似文献   

7.
Numbers of Pratylenchus penetrans in alfalfa and timothy, and to a lesser extent P. crenatus in timothy, increased substantially as temperature increased from about l0 C to 30 C. However, P. crenatus in alfalfa decreased in number as temperature increased. Mobility of P. crenatus in vertical soil columns decreased as temperature increased from 9.5 C to 28.5 C. Raising the soil pH from 5.0 to 6.9 in which alfalfa was grown increased the numbers of P. penetrans and greatly reduced the numbers of P. crenatus. The numbers of both nematode species in timothy were reduced significantly as soil pH was increased. The optimum soil pH for movement of P. penetrans was 6.0. Pratylenchus crenatus moved equally well over a range of pH 5.0 to 7.0.  相似文献   

8.
9.
The inner ear of the Late Cretaceous multituberculates Nemegtbaatar gobiensis and Chulsan-baatar vulgaris is described from serial sections and enlarged models. The size and proportions of the inner ear as a whole are as expected for extant small mammals. The lengths of the cochlea (Nemegtbaatar gobiensis, 3.0 mm, Chulsanbaatar vulgaris, 2.0 mm) are comparable to those of other multituberculates, when ratios of length of the cochlea to skull length are calculated. The vestibule is not as expanded in the two taxa as in Lambdopsalis, ?Meniscoessus, and ?Catopsalis; the estimated volume for Nemegtbaatar gobiensis is 9 mm3. A slightly laterally curved, anteriomedially directed cochlea, relatively robust ear ossicles, and the estimations of the area of the tympanic membrane and stapedial footplate in Chulsanbaatar suggest high-frequency hearing but a relatively low sensitivity to low-decibel sounds. The semicircular canals of Nemegtbaatar and Chulsanbaatar are fully developed; the size of the anterior, posterior, and lateral canals and their angles and proportions are comparable to those of extant mammals of similar size. The anterior semicircular canal of Nemegtbaatar forms a smooth half-circle and thus is more derived than the angular canal of Ornithorhynchus. The notable differences between the ratio of the width of the lateral semicircular canal to skull length and the size of the vestibule in Nemegtbaatar and the Paleocene multituberculate Lambdopsalis bulla are probably related to different modes of life.  相似文献   

10.
The anamorphic fungal genus Monotosporella (Ascomycota, Sordariomycetes) has been reco-vered from a piece of Early Eocene Indian amber, as well as from the surface of extant resin flows in New Caledonia. The fossil fungus was obtained from the Tarkeshwar Lignite Mine of Gujarat State, western India, and was part of the biota of an early tropical angiosperm rainforest. The amber inclusion represents the second fossil record of Sordariomycetes, as well as the first fossil of its particular order (either Savoryellales or Chaetosphaeriales). The fossil fungus is distinguished from extant representatives by possessing both short conidiophores and small two-septate pyriform conidia, and is described as Monotosporella doerfeltii sp. nov. Inside the amber, the anamorph is attached to its substrate, which is likely the degraded thallus of a cladoniform lichen. The extant New Caledonian species is assigned to Monotosporella setosa. It was found growing on semi-solidified resin flows of Agathis ovata (Araucariaceae), and is the first record of Monotosporella from modern resin substrates.  相似文献   

11.
Retrospective as well as recent records on DNA content, chromosome composition, and isozyme variation were analyzed critically to trace the evolution of species of the genusPlantago. Both in vivo as well as in vitro data were taken into consideration. The species withX 6 were considered to be ancestral, whereas those withX= 5 were considered to be more advanced. The cultivated species withX= 4 was thought to be a derivative ofX = 5. The data on isozyme variation supported the findings derived from DNA and chromosome composition.  相似文献   

12.
Yusuke Tsukatani  Chihiro Azai  Shigeru Itoh 《BBA》2008,1777(9):1211-1217
We studied the regulation mechanism of electron donations from menaquinol:cytochrome c oxidoreductase and cytochrome c-554 to the type I homodimeric photosynthetic reaction center complex of the green sulfur bacterium Chlorobium tepidum. We measured flash-induced absorption changes of multiple cytochromes in the membranes prepared from a mutant devoid of cytochrome c-554 or in the reconstituted membranes by exogenously adding cytochrome c-555 purified from Chlorobium limicola. The results indicated that the photo-oxidized cytochrome cz bound to the reaction center was rereduced rapidly by cytochrome c-555 as well as by the menaquinol:cytochrome c oxidoreductase and that cytochrome c-555 did not function as a shuttle-like electron carrier between the menaquinol:cytochrome c oxidoreductase and cytochrome cz. It was also shown that the rereduction rate of cytochrome cz by cytochrome c-555 was as high as that by the menaquinol:cytochrome c oxidoreductase. The two electron-transfer pathways linked to sulfur metabolisms seem to function independently to donate electrons to the reaction center.  相似文献   

13.
The investigation of Vernonia compactiflora afforded in addition to known compounds a hirsutinolide and a glaucolide; the latter is most probably the direct precursor of the former. The aerial parts of V. monocephala contain the same hirsutinolide as well as the corresponding acetate, while those of V. chalybaea afforded glaucolide B. A reinvestigation of the aerial parts of V. cotoneaster gave in addition to the allenic lactone isolated before two further known ones as well as a new glaucolide. The structures of the lactones were elucidated by spectroscopic methods and some chemical transformations. The erroneously assigned stereochemistry at C-10 in the hirsutinolides has been revised. The biogenetic relationship of the Vernonia lactones is discussed briefly.  相似文献   

14.
Reproduction of Criconernoides simile, Paratylenchus projectus, and Helicotylenchus pseudorobustus, alone and in certain combinations, was characterized during 50 days on the soybean cultivars Custer and Hood. Custer was the more suitable host for all three nematodes and C. simile was the most vigorous parasite on both cultivars. C. simile and H. pseudorobustus reproduced as well in combination as they did alone; addition of P. projectus to this combination did not alter results. Reproduction by P. projectus was repressed on both cultivars when it was combined with C. simile and H. pseudorobustus. The relative importance of time was assessed, as it relates both to the establishment of parasitism by applied nematodes and to the rate of development of larvae in the various host-parasite combinations. The necessity of characterizing as well as enumerating populations when evaluating population development of ectoparasitic nematodes was demonstrated.  相似文献   

15.
Hyaloscyphaceae is the largest family in Helotiales, Leotiomycetes. It is mainly characterized by minute apothecia with well-differentiated hairs, but its taxonomic delimitation and infrafamilial classification remain ambiguous. This study performed molecular phylogenetic analyses using multiple genes including the ITS-5.8S rDNA, the D1–D2 region of large subunit of rDNA, RNA polymerase II subunit 2, and the mitochondrial small subunit. The primary objective was to evaluate the phylogenetic utility of morphological characters traditionally used in the taxonomy of Hyaloscyphaceae through reassessment of the monophyly of this family and its genera. The phylogenetic analyses inferred Hyaloscyphaceae as being a heterogeneous assemblage of a diverse group of fungi and not supported as monophyletic. Among the three tribes of Hyaloscyphaceae only Lachneae formed a monophyletic lineage. The presence of hairs is rejected as a synapomorphy, since morphologically diversified hairs have originated independently during the evolution of Helotiales. The true- and false-subiculum in Arachnopezizeae are hypothesized to have evolved through different evolutionary processes; the true-subiculum is likely the product of a single evolutionary origin, while the false-subiculum is hypothesized to have originated multiple times. Since Hyaloscyphaceae sensu lato was not resolved as monophyletic, Hyaloscyphaceae sensu stricto is redefined and only applied to the genus Hyaloscypha.  相似文献   

16.
Synthetic bioregulators of poly-cis carotenoid biosynthesis   总被引:1,自引:0,他引:1  
Seventeen new bioregulators were synthesized and tested for their ability to induce the biosynthesis of poly-cis carotenes in the flavedo of Marsh white seedless grapefruit. The effects of these new bioregulators are the same as that of the previously reported dibenzylamines, but several of the new compounds are more effective and cause the accumulation of up to 162 μg/g dry wt of poly-cis carotenes in the flavedo as compared to the maximum of 74 μg/g dry wt observed previously. The compounds tested were substituted N-benzyl furfurylamines, N-benzyl, N-methyl furfurylamines and N-alkyl, N-methyl benzylamines. They demonstrate the ability of tertiary as well as secondary amines to stimulate the formation of poly-cis carotenes. The interaction of N-(4-bromobenzyl) furfurylamine, one of the more effective of the new compounds, with lycopene and β-carotene inducers is also reported.  相似文献   

17.
In order to test the response of phytoplankton to anthropogenic pressure, data of chlorophyll a concentration, phytoplankton abundance, and composition are analyzed in relation to anthropogenic pressure gradient and environmental variables such as temperature, salinity and nutrients. Investigated sites encompassed wide tropic range according to a preliminary determination of anthropogenic pressure, quantified through the LUSI index. Statistical analyses indicated nitrates and silicates as proxies of freshwater influence, and phytoplankton single metrics such as concentrations of chlorophyll a and abundances as indicators of anthropogenic pressure. Boundary values for different water quality classes for coastal waters under indirect freshwater influence (Type II) are obtained according to gradient between concentration of chlorophyll a and pressure index (LUSI), which empirically fit to exponential equation. The response of phytoplankton diversity was not linear, as the highest diversity was observed in the area with intermediate disturbance level. CCA analysis identified Skeletonema marinoii, Scrippsiella trochoidea, Guinardia flaccida, Leptocylindrus spp., Prorocentrum spp., Proboscia alata, Eutreptiella spp., and Pseudonitzschia spp. as local eutrophication indicators, whose abundances increased with nutrients loads.  相似文献   

18.
The Augochlora clade includes four genera: Augochlora Smith, Augochlorella Sandhouse, Ceratalictus Moure, and Pereirapis Moure. This is one of the richest and most widespread groups of Augochlorini bees. There are about 150 species, which occur from Argentina to Canada. The species of Augochlora clade are considered solitary to facultatively social, except Ceratalictus for which nothing is known. Wood nesting behavior arose once in the clade, in Augochlora sensu strictu. The objective of this study is to describe four new species and to present a revised phylogenetic analysis of the Augochlora clade for the placement of these species. The morphological matrix comprised 77 characters and 42 terminals, and resulted in two most parsimonious trees. The monophyly of the Augochlora clade is corroborated. Ceratalictus and Pereirapis are considered as sister groups and Ceratalictus inflexus sp. nov. came as sister to other species of Ceratalictus. Augochlora and Augochlorella are monophyletic and sister groups. Both extant subgenera of Augochlora were corroborated as monophyletic. Augochlorella comis is considered as sister group to the rest of Augochlorella species. All Augochlorella new species described belong to the Augochlorella ephyra group. Augochlorella kelliae sp. nov. is phylogenetically related to Augochlorella una. Augochlorella procliva sp. nov. and Augochlorella mavricera sp. nov. constitute a clade with Augochlorella acarinata. Including the new species, Augochlorella has 19 species and Ceratalictus 11 species. A revised key for species of Augochlorella and Ceratalictus is also presented in the Supplementary Information.  相似文献   

19.
20.
The rate of milk secretion in farrow cows may be expressed as See PDF for Equation, in which y = yield and t = time from calving. Pregnancy causes a decrease in yield which may be expressed as See PDF for Equation, in which i = inhibition or decrease in yield and p = time from conception. The constant K appears to be the same for various groups but b is roughly proportional to a. The decrease in yield associated with pregnancy is interpreted as due to a hormone. The hormone hypothesis also affords an interpretation of the increasing rate of milk secretion which occurs for a short time following parturition.  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