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排序方式: 共有381条查询结果,搜索用时 171 毫秒
1.
Stuart Fraser Mireia Gomez‐Gallego Judy Gardner Lindsay S. Bulman Sandra Denman Nari M. Williams 《Forest Pathology》2020,50(2)
Phytophthora pluvialis and Phytophthora kernoviae are the causal agents of important needle diseases on Pinus radiata in New Zealand. Little is known about the epidemiology of the diseases, making the development of control strategies challenging. To investigate the seasonality and climatic drivers of sporulation, inoculum traps, consisting of pine fascicles floating on water in plastic containers, were exchanged fortnightly at five sites in P. radiata plantations between February 2012 and December 2014. Sections of needle baits were plated onto selective media and growth of Phytophthora pluvialis and P. kernoviae recorded. To explore the generalizability of these data, they were compared to detection data for both pathogens from the New Zealand Forest Health Database (NZFHDB). Further, equivalent analyses on infection of Rhododendron ponticum by P. kernoviae in Cornwall, UK allowed the comparison of the epidemiology of P. kernoviae across different host systems and environments. In New Zealand, inoculum of P. pluvialis and P. kernoviae was detected between January–December and March–November, respectively. Inoculum of both species peaked in abundance in late winter. The probability of detecting P. pluvialis and P. kernoviae was greater at lower temperatures, while the probability of detecting P. pluvialis also increased during periods of wet weather. Similar patterns were observed in NZFHDB data. However, the seasonal pattern of infection by P. kernoviae in the UK was the opposite of that seen for sporulation in New Zealand. Phytophthora kernoviae was likely limited by warmer and drier summers in New Zealand, but by colder winter weather in the UK. These results emphasize the importance of considering both environmental drivers and thresholds in improving our understanding of pathogen epidemiology. 相似文献
2.
M. A. Gomez J. A. Navarro S. Gomez P. Camara J. C. Gomez A. Bernabé 《Anatomia, histologia, embryologia》1989,18(4):305-315
The structure and ultrastructure of the adenohypophyseal pars distalis in kids of the Murciano-granadiana breed (18 males and 12 females), aged 2-3 months and with an average carcass weight of 8 kg has been studied. Techniques of staining (Tetrachrome Herlant's, and Cleveland-Wolfe) and histochemistry (PAS, PAS-OG and BA-PAS-OG) contrasted with immunolabelling (PAP) have been used. In addition an ultrastructural study has been made and nucleus and cytoplasm, secretory granules, mitochondria and lysosomes have been measured with a semiautomatic image analyzer (IBAS-1). TSH cells are found in sagittal section in the anterior area and in an antero-caudodorsal band, and transversally in the ventral and medial region; they are 6% and their average size is 14.15 microns. Ultrastructurally they are a single cellular type with spherical granules whose size is 195 nm in males and 149 in females; these granules are characterized by a clear halo and a variable electronic density. The rough endoplasmic reticulum is found as slightly enlarged vesicles with a homogeneous and moderately electro-dense content or in concentric stratifications. 相似文献
3.
Single cells were mechanically isolated from leaf-derived callus of mature Juniperus oxycedrus L. These cells divided and gave rise to callus when plated on medium containing growth regulators. Best plating efficiency was obtained on a modified Schenk and Hildebrandt medium supplemented with 0.6 micro M 2,4-dichlorophenoxyacetic acid and 100 mg l(-1) casein hydrolyzate. Although single-cell-derived callus showed poor morphogenic potential, both adventitious shoots and embryogenic tissues differentiated from the callus. We also achieved induction of somatic embryogenesis in leaf explants of mature J. oxycedrus trees cultured in the presence of 6.0 or 10.0 micro M 2,4-dichlorophenoxyacetic acid or picloram. Frequency of embryogenic callus ranged from 6 to 18%; however, under the culture conditions tested, isolated embryos failed to develop into plants. 相似文献
4.
GA Presicce S Verberckmoes EM Senatore P Klinc D Rath 《Reproduction in domestic animals》2005,40(1):73-75
At the time of AI following Ovsynch protocol, a total of 51 buffaloes were randomly divided in a first group (n = 30) subjected to conventional AI into the uterine body with 20 million non-sex sorted frozen-thawed spermatozoa, while a second group (n = 21) was inseminated near the utero-tubal junction (UTJ) ipsilateral to the ovary carrying the preovulatory follicle with 2.5 million live (4 million total) sex-sorted frozen-thawed spermatozoa. The semen used for flowcytometric sorting was collected and processed on a farm in Italy, and then shipped to a laboratory in Germany. Eleven buffaloes were inseminated with X-chromosome bearing spermatozoa and 10 with Y-chromosome bearing spermatozoa. Conception rates after conventional and UTJ inseminations were 43.3% (n = 13) and 42.8% (n = 9) respectively (p = 0.97). Eight of the nine foetuses obtained after insemination with sexed spermatozoa corresponded to the sex as predicted by the cell sorting procedure (five male and four female foetuses by ultrasound vs six male and three female foetuses by cell sorting). In conclusion, for the first time buffalo semen has been successfully subjected to procedures for flowcytometric sperm sorting and freezing. Low doses of sexed spermatozoa have been deposited near the UTJ giving conception rates similar to those of conventional AI with full dose. 相似文献
5.
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7.
Descenzo RA Engel SR Gomez G Jackson EL Munkvold GP Weller J Irelan NA 《Phytopathology》1999,89(10):884-893
ABSTRACT Eutypa dieback is a perennial canker disease that adversely affects grape (Vitis vinifera) production throughout the world. The causal agent has been known as either Eutypa armeniacae or E. lata, and it has been unclear whether the two taxa are separate species. We analyzed 115 isolates of Eutypa and conspecific strains, including 106 from California, using amplified fragment length polymorphism (AFLP) and sequence analysis of the ribosomal DNA (rDNA) internal transcribed spacer (ITS) sequence. Strains from cultivated plant species exhibited an average genetic distance of 0.34, as calculated by the DICE coefficient (NTSYS-pc software). An unweighted pair-group method with arithmetic averages dendrogram revealed a genetically distinct (distance of 0.73) group of Eutypa strains from valley oak (Quercus lobata) and madrone (Arbutus menziesii) and a strain from grape. Analysis of rDNA ITS sequences strongly supported the genetically distinct cluster detected in the AFLP data. Combined data indicated the presence of two species of Eutypa (E. armeniacae and E. lata) in our sample population. However, both Eutypa species were capable of infecting native and cultivated hosts, suggesting the potential for native tree species to serve as inoculum sources for grape infection in California. Further investigations of E. armeniacae and E. lata would contribute to the development of a successful disease management strategy. 相似文献
8.
Gil MC Peña FJ Hermoso De Mendoza J Gomez L 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2003,50(10):484-487
This paper reports on the genital lesions observed in adult male and female goats from a commercial flock in the Extremadura region of southwestern Spain, following an outbreak of contagious agalactia syndrome caused by Mycoplasma agalactiae and M. putrefaciens. Although both species were isolated from several organs, M. putrefaciens was the only agent isolated from the genital lesions reported here, characterized by desquamative salpingitis and cystic catarrhal metritis in females and by testicular degeneration in males. Mycoplasma putrefaciens was isolated from the testes of only one of the males examined. 相似文献
9.
Katakura K Mimori T Furuya M Uezato H Nonaka S Okamoto M Gomez L EA Hashiguchi Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2003,65(5):649-653
PCR amplification and nucleotide sequencing of the mini-exon gene revealed that four strains isolated from a sloth (Choloepus hoffmanni), a squirrel (Sciurus granatensis) and two sandflies (Lutzomyia hartmanni) in Ecuador were indistinguishable from Endotrypanum monterogeii. Another strain isolated from Lu. hartmanni showed the high sequence similarity to E. schaudinni. Since three of these strains have been previously identified as Leishmania (Viannia) equatorensis, the results demonstrate that L. (V.) equatorensis is genetically closely related to the genus Endotrypanum. The present study also indicates that Endotrypanum species are distributed in arboreal animals and sandflies in Ecuador, and that mini-exon gene amplification is useful for epidemiological studies of Leishmania and Endotrypanum in the New World. 相似文献
10.
HH Ortega NR Salvetti C Baravalle JA Lorente GA Mira 《Reproduction in domestic animals》2006,41(3):204-209
The objectives of this work were to determine the changes in the expression of neuroendocrine markers in Leydig cell by oestradiol treatment, and to determine whether testosterone is able to recover partially the effects of hormonal suppression induced by oestradiol. Adult male rats were injected daily with either 50 microg of oestradiol or oestradiol plus testosterone propionate (25 mg every 3 days) for 15 days. The animals were sacrificed and testicles were dissected and processed by routine histological protocols. FSH and LH serum levels were determined by radioimmunoassay. The visualization of antigens was achieved by the streptavidin-peroxidase immunohistochemical method. Antibodies against chromogranin A (CrA), S-100 protein (S-100), P substance (PS), synaptofisin (SYN), neurofilament protein (NF), gliofibrillary acidic protein (GFAP) and neuron specific enolase (NSE) were used. The mean LH and FSH serum concentrations were consistently suppressed with hormonal treatments. Intermediate filaments (NF and GFAP) showed no difference in their expression. The expression of S-100, NSE and SYN was significantly lower in both hormone-treated groups. In oestradiol-treated rats, the immunoreactivity of CrA and SP decreased significantly but was restored after testosterone supplementation. Although the nature and functions of many of these substances in Leydig cells remain unknown, these results are consistent with the hypothesis that the expression of some neuroendocrine markers is hormonally controlled. 相似文献