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.
We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan.  相似文献   

2.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.  相似文献   

3.
Blowflies use discrete and ephemeral substrates to feed their larva. After they run out of food, the larvae begin to disperse in order to find adequate places for pupation or additional food sources, a process named post-feeding larval dispersal. Briefly state the aspects and why they are important were studied in a circular arena of 25 cm in diameter and covered with wood shavings to a height of 40 cm allowing post-feeding dispersal from the center of the arena. Larvae of both Chrysomya albiceps and C. megacephala were used in five experiments for each species. For each pupa location, determined as distance from the center, depth, and weight were evaluated. Statistical tests were done to verify the relation between weight, depth and distance for pupation and for larvae of two species shows that the media distance is significantly different for two species and for C. megacephala this distance is greater than the distance for C. albiceps. The depth too is different for each species, as the larvae of C. megacephala buries deeper than C. albiceps. With relation of weight, there is no statistic evidence that have any difference between weights for pupation for each species.  相似文献   

4.
Floral development in three species each of Leptospermum and Kunzea, and one species of Agonis, is described and compared. Differences in the number of stamens and their arrangement in the flower at anthesis are determined by the growth dynamics of the bud. In Leptospermum, early expansion of the bud is predominantly in the axial direction and causes the stamen primordia to be initiated in antepetalous chevrons. In Kunzea, early expansion occurs predominantly in the lateral direction and successive iterations of stamen primordia are inserted alternately at more or less the same level. In both genera, further expansion in the lateral plane spreads the stamens into a ring around the hypanthium. Agonis flexuosa is similar to Leptospermum. Other variable factors include the timing at which stamen initiation commences (earlier in Leptospermum than Kunzea), the duration of stamen initiation (hence the total number of stamens produced – varies within genera), and very late differential expansion that forces stamens into secondary antesepalous groups in A. flexuosa and L. myrsinoides.The authors thank Dr H. Toelken for kindly providing some material and the impetus for this project. This research was supported by Australian Research Council grant AS19131815.  相似文献   

5.
A pea rust fungus, Uromyces viciae-fabae, has been classified into two varieties, var. viciae-fabae and var. orobi, based on differences in urediniospore wall thickness and putative host specificity in Japan. In principal component analyses, morphological features of urediniospores and teliospores of 94 rust specimens from Vicia, Lathyrus, and Pisum did not show definite host-specific morphological groups. In molecular analyses, 23 Uromyces specimens from Vicia, Lathyrus, and Pisum formed a single genetic clade based on D1/D2 and ITS regions. Four isolates of U. viciae-fabae from V. cracca and V. unijuga could infect and sporulate on P. sativum. These results suggest that U. viciae-fabae populations on different host plants are not biologically differentiated into groups that can be recognized as varieties.Contribution no. 184, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan  相似文献   

6.
Agrobacterium tumefaciens-mediated transformation system for perilla (Perilla frutescens Britt) was developed. Agrobacterium strain EHA105 harboring binary vector pBK I containing bar and γ-tmt cassettes or pIG121Hm containing nptII, hpt, and gusA cassettes were used for transformation. Three different types of explant, hypocotyl, cotyledon and leaf, were evaluated for transformation and hypocotyl explants resulted in the highest transformation efficiency with an average of 3.1 and 2.2%, with pBK I and pIG121Hm, respectively. The Perilla spp. displayed genotype-response for transformation. The effective concentrations of selective agents were 2 mg l−1 phosphinothricin (PPT) and 150 mg l−1 kanamycin, respectively, for shoot induction and 1 mg l−1 PPT and 125 mg l−1 kanamycin, respectively, for shoot elongation. The transformation events were confirmed by herbicide Basta spray or histochemical GUS staining of T0 and T1 plants. The T-DNA integration and transgene inheritance were confirmed by PCR and Southern blot analysis of random samples of T0 and T1 transgenic plants.  相似文献   

7.
8.
Okigbo RN 《Mycopathologia》2005,159(2):307-314
The potential of isolates of Bacillus subtilis from yam farm soil to control rot of yam in storage barns was investigated. Yam tubers inoculated in vivo with B. subtilis showed no rot while those inoculated with Aspergillus niger, Botryodiploidia theobromae or Penicillium oxalicum showed considerable rot. The set of yams in which B. subtilis and the fungi were simultaneously inoculated produced rot whereas those in which B. subtilis was inoculated a day before the fungi was inoculated were totally reduced or free of rot. Many fewer fungi were isolated from the surface of tubers treated with B. subtilis than from the untreated (control) and there was high recovery of B. subtilis (99–100%) throughout the period of storage. Rot build up was faster in uninoculated control tubers or those inoculated with a spoilage fungus, while those treated with the antagonist were totally reduced or free of rot. The culture filtrate of B. subtilis prevented spore germination in some spoilage fungi. The importance of this study in relation to farmers in developing countries is discussed.  相似文献   

9.
Arachis correntina (Burkart) Krapov. & W.C. Gregory is a herbaceous perennial leguminous plant growing in the Northeast of the Province Corrientes, Argentina. It is important as forage. The development of new A. correntina cultivars with improved traits could be facilitated through the application of biotechnological strategies. The purpose of this study was to investigate the plant regeneration potential of mature leaves of A. correntina in tissue culture. Buds were induced from both petiole and laminae on 0.7% agar-solidified medium containing 3% sucrose, salts and vitamins from Murashige and Skoog (MS) supplemented with 0.5–25 M thidiazuron (TDZ). Shoot induction was achieved by transference of calli with buds to MS supplemented with 5 M TDZ. Fifty-four percent of the regenerated shoot rooted on MS + 5 M naphthaleneacetic acid. Histological studies revealed that shoots regenerated via organogenesis.  相似文献   

10.
Fusarium oxysporum (isolate PSM 197) based mycoherbicide was evaluated for its efficacy under field conditions in trials conducted during 1999--2001 cropping seasons in the Nigerian savanna. In the 1999 cropping season, spot application of 5--10 g of mycoherbicide was found to give effective control of Striga hermonthica. Results of on-farm trials at Barhim and Dutsen-Ma areas showed the application of the mycoherbicide to significantly (p= 0.05) increase stand count at both 3 weeks and at harvest, reduced Striga shoot count and increased crop yield in both improved and local sorghum varieties, as compared with the same varieties not treated with the mycoherbicide. Results establish the efficacy of F. oxysporum as a mycoherbicide and the need for further development of the mycoherbicide into formulated granules or seed treatment for use in control of S. hermonthica under field conditions.  相似文献   

11.
Sex ratio distorting endosymbionts induce reproductive anomalies in their arthropod hosts. They have recently been paid much attention as firstly texts of evolution of host-symbiont relationships and secondly potential biological control agents to control arthropod pests. Among such organisms, Wolbachia and Cardinium bacteria are well characterized. This study aims at probing such bacteria in the Osmia community to evaluate their potential utilization to control arthropod pests. Among 17 PCR tested species, Osmia cornifrons and a parasitic fly are infected with Wolbachia and a mite species is infected with Cardinium. Phylogenetic tree analyses suggest that horizontal transfer of the bacteria occurred between phylogenetically distant hosts.  相似文献   

12.
Effectiveness of the entomopathogenic fungus Metarhizium anisopliae, for controlling nymphal Ixodes scapularis, was tested in laboratory and field trials. In the laboratory, M. anisopliae (Metschnikoff) Sorokin strain ESC1 was moderately pathogenic, with an LC50 of 107 spores/ml and induced 70% mortality at 109 spores/ml. In a field study, however, 109 spores/ml M. anisopliae did not effectively control questing I. scapularis nymphs, and significant differences were not detected in pre- and post-treatment densities. For nymphs collected and returned to the laboratory for observation, mortality was low in treatment groups, ranging from 20 to 36%. To assess whether a chemical acaricide would synergistically enhance pathogenicity of the fungus, we challenged unfed nymphal I. scapularis with combinations of M. anisopliae and permethrin, a relatively safe pyrethroid acaricide, in two separate bioassays. Significant interactions between M. anisopliae and permethrin were not observed, supporting neither synergism nor antagonism.  相似文献   

13.
The nucleotide sequences of ten SP11 and nine SRK alleles in Raphanus sativus were determined, and deduced amino acid sequences were compared with those of Brassica SP11 and SRK. The amino acid sequence identity of class-I SP11s in R. sativus was about 30% on average, the highest being 52.2%, while that of the S domain of class-I SRK was 77.0% on average and ranged from 70.8% to 83.9%. These values were comparable to those of SP11 and SRK in Brassica oleracea and B. rapa. SP11 of R. sativus S-21 was found to be highly similar to SP11 of B. rapa S-9 (89.5% amino acid identity), and SRK of R. sativus S-21 was similar to SRK of B. rapa S-9 (91.0%). SP11 and SRK of R. sativus S-19 were also similar to SP11 and SRK of B. oleracea S-20, respectively. These similarities of both SP11 and SRK alleles between R. sativus and Brassica suggest that these S haplotype pairs originated from the same ancestral S haplotypes.  相似文献   

14.
Ant-gardens represent a special type of association between ants and epiphytes. Frequently, two ant species can share the same nest in a phenomenon known as ‘parabiosis’, but the exact nature (i.e., mutualistic or parasitic) of this interaction is the subject of debate. We thus attempted to clarify the mutual costs and benefits for each partner (ants and plants) in the Crematogaster levior/Camponotus femoratus ant-garden parabiosis. The ants’ response to experimental foliar damage to the epiphytes and to the host tree as well as their behavior and interactions during prey capture were investigated to see if the purported parasitic status of Cr. levior could be demonstrated in either the ant-ant or in the ant-plant interactions. The results show that both species take part in protecting the epiphytes, refuting the role of Cr. levior as a parasite of the ant-garden mutualism. During capture of large prey Ca. femoratus took advantage from the ability of Cr. levior to discover prey; by following Cr. levior trails Ca. femoratus workers discover the prey in turn and usurp them during agonistic interactions. Nevertheless, the trade-off between the costs and benefits of this association seems then to be favorable to both species because it is known that Cr. levior benefits from Ca. femoratus building the common carton nests and furnishing protection from vertebrates. Consequently, parabiosis can then be defined as the only mutualistic association existing between ant species, at least in ant-gardens. Received 31 August 2006 ; revised 8 December 2006 ; accepted 12 December 2006  相似文献   

15.
Summary  A new monotypic bamboo genus Phuphanochloa (Poaceae: Bambusoideae) from north-eastern Thailand is described, together with a new species, P. speciosa.  相似文献   

16.
Three wild red-legged partridges (Alectoris rufa) from intensively managed hunting areas in Spain were received for necropsy. They showed granulomatous lesions in different parts of the body, mainly in liver and spleen. Microscope examination of the granulomas showed central caseous necrosis and large amounts of acid-fast bacilli, surrounded by epitheloid cells, giant cells, and lymphocytes. Attempts to isolate and culture the bacillus in Colestsos medium were unsuccessful, but the polymerase chain reaction technique revealed the presence of microorganisms belonging to the Mycobacterium avium complex in one of the partridges. This is the first report of avian tuberculosis in free-living red-legged partridges.  相似文献   

17.
A survey for entomopathogenic fungi of Musca domestica adults was conducted in poultry houses in La Plata, Buenos Aires province, Argentina, during the years 2002 and 2003. Adult house flies were found infected with the fungus Beauveria bassiana (Bals.) Vuill. (Deuteromycotina: Hyphomycetes) from field collections, with a natural infected prevalence between 0.4–1.45%. This is the first record of natural infections of house flies caused by B. bassiana for the neotropics. Pathogenicity assays under laboratory conditions showed 94% adult mortality at 14 days post challenge. CIC fellow  相似文献   

18.
Pteromalus cerealellae (Ashmead) (Hymenoptera: Pteromalidae) is an ectoparasitoid of several stored-product insect pests. Very little information has been published on its biology and development in host larvae, which typically are concealed within seeds. We documented the development of P. cerealellae within fourth instar larvae of its concealed host, Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) infesting cowpea seeds. The preimaginal life stages of the parasitoid were characterized for the first time using morphological structures revealed by microscopic techniques including scanning electron microscopy. Pteromalus cerealellae produces hymenopteriform eggs and larvae. Eggs hatch into 13-segmented first instar larvae with peripneustic condition of spiracles. The larvae have simple, tusk-like mandibles, whereas the mandibles of the pupae and the adults are of the conventional toothed types. Using statistical analyses of the sizes of the larval mandibles and head capsules in conjunction with reliable characters such as the number of exuviae on the body of parasitoid larvae, cuticular folding, and excretion of the meconium, we recorded four larval instars for P. cerealellae. The data showed significant positive correlations between larval mandible lengths and widths of larval head capsules, as well as between mandible lengths and larval instars, suggesting that mandible length is a good predictor of the number of instars in P. cerealellae. Developmental time from egg to adult emergence was ∼12 d for females and ∼11 days for males at 30 ± 1°C, 70 ± 5% r.h. and 12L:12D photoperiod.  相似文献   

19.
Ruan L  He W  He J  Sun M  Yu Z 《Antonie van Leeuwenhoek》2005,87(4):283-288
Previous work from our laboratory has shown that most of Bacillus thuringiensis strains possess the ability to produce melanin in the presence of l-tyrosine at elevated temperatures (42 °C). Furthermore, it was shown that the melanin produced by B. thuringiensis was synthesized by the action of tyrosinase, which catalyzed the conversion of l-tyrosine, via l-DOPA, to melanin. In this study, the tyrosinase-encoding gene (mel) from B. thuringiensis 4D11 was cloned using PCR techniques and expressed in Escherichia coli DH5 . A DNA fragment with 1179 bp which contained the intact mel gene in the recombinant plasmid pGEM1179 imparted the ability to synthesize melanin to the E. coli recipient strain. The nucleotide sequence of this DNA fragment revealed an open reading frame of 744 bp, encoding a protein of 248 amino acids. The novel mel gene from B.thuringiensis expressed in E. coli DH5 conferred UV protection on the recipient strain.  相似文献   

20.
In the present investigation, the interspecific somatic hybridization between tuber mustard and red cabbage was established in order to introduce valuable genes from red cabbage (Brassica oleracea) into Brassica juncea. Prior to fusion treatment, protoplasts of red cabbage were inactivated with 2 mM iodoacetamide to inhibit cell division. Micro-calluses were obtained at a frequency of 10.3% after approximately 5 weeks culture following protoplast fusion. Some of the fusion-derived calluses possessed red pigmented cells after being transferred to proliferation medium, and they were presumably considered to be somatic hybrid cell lines. Plantlets were regenerated from 12 cell lines, of which nine plantlets exhibited characteristics intermediate of both parents in terms of plant morphology. With the exception of common protein bands featured by two parents, there were unique banding patterns produced in the hybrids by using SDS-PAGE analysis. By chromosome countings, it was showed that they ranged approximately from 2n=30 to 42 in chromosome numbers. Their hybridity were further confirmed by RAPD analysis revealing that genes of both parents were partially incorporated into the hybrids. Positively, all these hybrids were capable of seed-setting. The pod-setting was 4.2 in somatic hybrid H7 when backcrossed with tuber mustard.  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