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991.
P R?dl 《Folia parasitologica》1979,26(3):265-274
The transfer of fleas Megabothris turbidus, Ctenophthalmus agyrtes, Nosopsyllus fasciatus etc. was investigated by labelling the bank vole (Clethrionomys glareolus Schreb.) with radioactive phosphorus. On the one hand, the process of flea transfer was traced among different individuals of the same host species, and on the other, among different host species (C. glareolus, Apodemus flavicollis Melch.). The investigations revealed that the flea transfer in a rodent nest visited by another host depended partly on the number of fleas present in the nest, partly on the period spent by the new-comer in it. Conversely, the number of fleas transferred in the nest by the newly arrived host depended on the temperature of nest bedding and on the initial nest occupation by other host. 相似文献
992.
993.
The tissue reaction to Cysticercus bovis in the lung of cattle with an experimental infection was an inflammatory rim originating in the immediate vicinity of the cysts. The cysts recovered at days 83 and 102 p.i. contained living cysticerci. The rim was composed either of a layer of high histiocytes organized in palisades (at day 83 p.i.), or a lyer of flat histiocytes (at day 102 p.i.). The outer layer of the rim consisted of fibroblasts, reticular cells and a different number of eosinophil- and neutrophil luekocytes. On the periphery, the rim was formed by granulation tissue infiltrated with lymphoplasmocytes. At the border between the layers of the inflammatory rim there were conspicuous foci of a necrotic appearance typical of a tissue reaction to C. bovis. 相似文献
994.
sigma DDT residues in the St. Lucie River bottom sediments increased after Lake Okeechobee water was discharged through the St. Lucie Canal into the area. sigma DDT levels were highest in sediment samples from the Palm City area, ranging from 1.8 ppb to 6.15 ppb. Sediment samples from the A1A Highway Bridge area contained 1.6-6.8 ppb Aroclor 1254. Levels of polychlorinated biphenyls (PCBs) and sigma DDT in sediment samples from the junction of the St. Lucie and Indian Rivers were not detectable. Surface water samples from the estuary did not show any detectable DDT or PCB residues. 相似文献
995.
Newby TJ Stokes CR Huntley J Evans P Bourne FJ 《Veterinary immunology and immunopathology》1979,1(1):37-47
The immune response of pigs fed 200 mg per day of dinitrophenylated bovine gamma globulin has been evaluated in terms of the antibody and lymphocyte responses and of the induction of tolerance and immune exclusion. Although dosing for ten days resulted in a small IgA response as indicated by splenic plaque forming cells, serum antibody could only be detected when dosing was continued for 42 days. secretory antibody was detected at any time. Antigen feeding for two weeks rendered the animals hyporesponsive to subsequent parenteral antigenic challenge but had little effect upon their ability to exclude an oral dose of antigen from the circulation. 相似文献
996.
K. P. Bland 《Veterinary research communications》1979,3(1):125-136
The function and suppression of urine spraying by cats is discussed as also is the source of tom-cat odour. It seems unlikely that tom-cat odour is derived from the lipid in the proximal convoluted tubule of the kidney, however its production by the anal glands has not yet been proven. Although male cats show a flehmen response when sniffing urine, smell seems to play a more important role in reproduction in the female than the male. The available data suggests that valeric acid may function as a female/female pheromone in cats by inducing or facilitating oestrus. Nepetalactone, the active ingredient of catnip, is probably not related to any naturally occurring pheromone in the cat but simply acts as an hallucinogenic drug. 相似文献
997.
998.
小麦对条锈病的水平抗病性研究初报 总被引:4,自引:0,他引:4
将小麦品种采用随机区组的田间设计种于小种病圃中,以鉴定和测定其水平抗性。根据各个“品种——小种”组合的相对病情指数的方差分析的结果,有些品种,如农大311、西农6028和丰产3号,其品种——小种互作高度显著,被鉴定为具有垂直抗性,另外一些品种,对试验所用的小种并无专化性,并且在大田生产中已显出20多年的持久的中度抗性,初步推测为属水平抗性。在后一类中,有些品种,如平原50,表现为中等反应型,其余则属于呈典型感病的迟锈慢锈类型。在迟锈慢锈品种的病指的对数矫正值(logits)和病圃的锈病强度(以感病对照品种的病指表之)的对数矫正值之间发现了直线回归。 相似文献
999.
Dr. L. Bos Dr. M. P. Benetti 《European journal of plant pathology / European Foundation for Plant Pathology》1979,85(6):241-251
Most of 43 viruses could easily be detected directly in 53 out of 66 leaf samples dried and stored over CaCl2 for varying periods of time up to 20 1/2 years. Detection usually was with PTA pH 6.5, but alfalfa mosaic, cucumber mosaic and tomato aspermy viruses required PTA pH 3.0 to 4.0. Bean common mosaic, cowpea aphid-borne mosaic and cowpea mosaic viruses were also easily observed in newly dehydrated samples obtained for diagnosis from Morocco and Tanzania.Broad bean wilt virus, cowpea mosaic virus and cucumber mosaic virus were detected with agar gel-diffusion tests in dry leaf material ground in buffer. This serological assay demonstrated a high concentration of cucumber mosaic virus in leaf material dried over CaCl2 20 years ago. This paper further coroborates the value of the CaCl2 method of dehydration and storage of plant viruses in leaf material.Samenvatting Zeer uiteenlopende plantevirussen kunnen goed worden bewaard in bladmateriaal van geïnfecteerde planten dat is gedroogd en bewaard boven CaCl2. Bij rechtstreekse elektronenmicroscopische toetsing van 66 monsters met verschillende isolaten van 43 virussen konden in 53 monsters gemakkelijk virusdeeltjes worden waargenomen (Tabel 1 en Fig. 1 en 2). Meestal lukte dit met fosforwolfraamzuur pH 6,5 dat doorgaans voor in ruw plantesap voorkomende virussen wordt gebruikt. Bij luzernemozaïekvirus en komkommermozaïek virus gelukte dit alleen maar bij lagere pH (3,0 en 4,0). Ook het tomate-aspermievirus was dan veel gemakkelijker aantoombaar. Methylaminewolfraamzuur gaf geen beter resultaat.Draden van bonerolmozaïekvirus en van cowpea aphid-borne mosaic virus en bolletjes van cowpea mosaic virus waren snel waarneembaar in elektronenmicroscopische preparaten gemaakt van bladmateriaal van recent uit Marokko en Tanzania ontvangen monsters.Cowpea mosaic virus, tuinboneverwelkingsvirus en komkommermozaïekvirus konden eveneens gemakkelijk en snel serologisch worden aangetoond in met bufferoplossing vermalen droog blad van respectievelijk cowpea, erwt en tabak. Het laatstgenoemde, reeds 20 1/2 jaar geleden gedroogde bladmateriaal, bleek in vergelijking met pas geïnoculeerd vers blad van komkommer enChenopodium quinoa zelfs zeer veel serologisch actief virusmateriaal te bevatten (Fig. 3).De beschreven waarnemingen bevestigen nogmaals de waarde van de toegepaste methode van virusbewaring en tonen aan dat het mogelijk is vele virussen te herkennen in van elders ontvangen gedroogde bladmonsters, zonder het risico te lopen van virusontsnapping, zoals altijd aanwezig bij werk met toetsplanten in de kas.Guestworker from Istituto Sperimentale per la Patologia Vegetale, Rome, Italy, participating in the investigations from September 21 to December 21, 1977. 相似文献
1000.
H. A. Van Hoof H. Huttinga A. Knaap H. P. Maas Geesteranus W. H. M. Mosch D. G. J. De Raay-Wieringa 《European journal of plant pathology / European Foundation for Plant Pathology》1979,85(3):87-98
In 1975 many tumours were observed in plants ofBegonia Schwabenland grown in Aalsmeer. Submersion of the roots ofNicotiana megalosiphon seedlings in a homogenate of tumorous tissue, induced tumours after two weeks. Short periods of submergence yielded results similar to those obtained after longer periods. Tumour homogenates lost their infectivity after ten min at 50°C. Aphids transmitted the infectious agent.Treatment with propylene oxide did not inhibit infectivity completely. Filtration through a 450 nm filter removed the infectious agent.Tobacco tumor virus or a viroid could not be isolated. Cultures ofCorynebacterium fascians, isolated from tumours ofN. megalosiphon were highly infectious and induced tumours in healthyN. megalosiphon andBegonia. Tumorous tissue homogenates ofPelargonium zonale, Dahlia sp.,Gladiolus sp., andLilium sp. also caused tumours inN. megalosiphon, from whichC. fascians was isolated. It was not possible to produce tumours inN. megalosiphon with homogenates from roses with symptoms of bud proliferation.Samenvatting In 1975 werden vele tumoren waargenomen inBegonia Schwabenland op Aalsmeerse bedrijven (Fig. 1). De infectiositeit van tumorweefsel kon goed en snel worden vastgesteld door de wortels van zaailingen vanNicotiana megalosiphon in een homogenaat van tumorweefsel te dompelen. Tumoren ontstonden na twee weken, de eindbeoordeling geschiedde na een maand (Fig. 2). Ook verschillende andereNicotiana spp.,Melilotus officinalis (Fig. 3) enPisum odoratum (Fig. 4) werden aangetast.Bij de infectiositeitstoets gaven zeer korte dompeltijden even goede resultaten als langere (Tabel 1). Infectieus sap verloor zijn infectievermogen na 10 min verhitting bij 50°C. Bladluizen brachten de smetstof over. Propyleenoxide verminderde de infectiositeit wel, doch onderdrukte deze niet totaal. Bij filtratie door een 450 nm filter bleef het infectieuse agens op het filter achter. Het tumor-inducerende agens was ook aanwezig in die delen van planten met tumoren welke gezond leken en het ging voor een gering deel over met zaad (Tabel 2).Uit tumoren konden wij geen tabakstumorvirus of een viroïde isoleren. Culturen vanCorynebacterium fascians, geïsoleerd uit tumoren vanN. megalosiphon bleken zeer infectieus en veroorzaakten tumoren inN. megalosiphon enBegonia. Homogenaten van tumorweefsel vanPelargonium zonale, dahlia (Fig. 5), gladiool (Fig. 6) enLilium Mid Century Hybrid Enchantment (Fig. 7) veroorzaakten ook tumoren opN. megalosiphon, waaruitC. fascians werd geïsoleerd. Met sap van kroeskopzieke rozen konden wijN. megalosiphon niet besmetten. 相似文献