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31.
JAMES E. JOY 《The Journal of eukaryotic microbiology》1972,19(2):264-265
SYNOPSIS. Kudoa branchiata sp. n. (Myxosporidea: Chloromyxidae) is described from the gills of the marine sciaenid fish, Leiostomus xanthurus Lacépède, from Clear Lake, Texas. Twelve of the 429 hosts examined from 10 September 1970 to 28 April 1971, were infected. Eight of the 12 infected fish were collected in February and March 1971—a period during which only 13% of the total host sample was taken. The mean total length of infected hosts was 149 mm, with a range of 112–185 mm. The mean number of myxosporidean cysts per infected host was 3.5, with a range of 1–11. 相似文献
32.
The influence of temperature was studied in relation to nitrate reductase activity of creeping bentgrass (Agrostis palustris Huds. cv. ‘Toronto’) a cool season grass and bermudagrass (Cynodon dactylon L. cv. ‘Tifgreen’) a warm season grass. Maximum nitrate reductase activity of both species occurred at 20°C. The nitrate reductase level in bentgrass leaves was reduced when grown at 35°C while bermudagrass leaves were relatively unaffected. The activity per se of the bentgrass enzyme preparation was inhibited rather than synthesis of the enzyme. 相似文献
33.
The plant growth-regulating activities of chloro-, bromo- and iodo-isomers in 2,5-, 2,3,5- and 2,3,6-substituted benzoic acids were assessed in the wheat cylinder, pea segment and pea curvature tests. Their effects in the tomato-leaf epinasty test were also investigated. Replacing an ortho-chloro atom by bromine had little or no effect on activity. An ortho-iodo substituent, however, reduced activity in the 2,3,6-substituted series and almost completely inhibited it in the 2,5- substituted series. This decreased activity of ortho-iodo-substituted isomers is visualized as being due to a steric inhibition of the attachment of the carboxyl group to its receptor unit prior to the initiation of the growth response. 相似文献
34.
This work examined three possible explanations of growth rateresponses to leaf area index (LAI) in which growth rate perunit of ground area (crop growth rate, CGR) increased to a plateaurather than decreasing above an optimum LAI at which all lightwas intercepted. Single leaf photosynthetic measurements, andwhole plant 24 h photosynthesis and respiration measurementswere made for isolated plants and plants in stands using Amaranlhushybridus, Chenopodium album, and two cultivars of Glycine maxgrown at 500 and 1000 µimol m2 S1 photosyntheticphoton flux density at 25 °C. CGR, relative growth rate(RGR), and LAI were determined from 24 h carbon dioxide exchangeand leaf area and biomass measurements. Respiration increasedrelative to photosynthesis with crowding in A. hybridus andthere was an optimum LAI for CGR. In contrast, the ratio ofrespiration to photosynthesis was constant across plant arrangementin the other species and they had a plateau response of CGRto LAI. Neither increased leaf photosynthetic capacity at highLAI nor a large change in biomass compared to the change inLAI could account for the plateau responses. It was calculatedthat maintenance respiration per unit of biomass decreased withdecreasing RGR in C. album and G. max, but not A. hybridus,and accounted for the plateau response of CGR to LAI. Sincesimilar decreases in maintenance respiration per biomass atlow RGR have been reported for several other species, a constantratio of respiration to photosynthesis may occur in more speciesthan constant maintenance respiration per unit of biomass. Amaranlhus hybridus L., Chenopodium album L., Glycine max L Merr, soybean, photosynthesis, respiration, growth, leaf area index 相似文献
35.
DONG-JIN LEE JAMES P. A. NOBLE 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1990,23(2):179-193
Lee, D.-J. & Noble, J. P. A. 1990 04 15: Colony development and formation in halysitid corals. Lethaia , Vol. 23. pp. 179–193. Oslo. ISSN 0024–1164.
Modes of colony formation and their relationship with colony morphology, size and substrate characteristics in species of halysitid corals have been studied. Two distinctive modes of colony formation in halysitids are proposed. In the monoplanulate mode. represented by Catenipora snnplex . the colony is developed from a single protocorallite and colony formation is achieved by a combination of asexual increase and intracolony fusions. In contrast, the polyplanulatc mode is demonstrated by C. escharoides . in which the early colony formation is achieved primarily by fusions of many 'incipicnt colonies' of more than a single planulate origin and of different generations. The latter mode has not previously been described in tabulates and has significant implications for coloniality, reproductive and life history characteristics, histo-compatibility and adaptative ecology. The colony size and morphology. and The distribution of halysitid species were primarily determined by the modes of colony formation and the substrate characteristics. Colonies of the monoplanulate mode. when developed on soft substrates, exhibit a small and spherical morphology with isolated distribution patterns, while those developed on hard substrates are tabular and variable in size. depending on the availability of substrate. In colonies of the polyplanulate mode, on the other hand. the size of the colony is largely dependent on The frequency and timing of allograft fusion. They are characteristically found on soft substrates. often as dense mono specific thickets. The mode of colony formation in halysitids is probably species-specific and results in the adaptation to substrates. * Colony development, halysitid corals, Anticosti Island. Gotland . 相似文献
Modes of colony formation and their relationship with colony morphology, size and substrate characteristics in species of halysitid corals have been studied. Two distinctive modes of colony formation in halysitids are proposed. In the monoplanulate mode. represented by Catenipora snnplex . the colony is developed from a single protocorallite and colony formation is achieved by a combination of asexual increase and intracolony fusions. In contrast, the polyplanulatc mode is demonstrated by C. escharoides . in which the early colony formation is achieved primarily by fusions of many 'incipicnt colonies' of more than a single planulate origin and of different generations. The latter mode has not previously been described in tabulates and has significant implications for coloniality, reproductive and life history characteristics, histo-compatibility and adaptative ecology. The colony size and morphology. and The distribution of halysitid species were primarily determined by the modes of colony formation and the substrate characteristics. Colonies of the monoplanulate mode. when developed on soft substrates, exhibit a small and spherical morphology with isolated distribution patterns, while those developed on hard substrates are tabular and variable in size. depending on the availability of substrate. In colonies of the polyplanulate mode, on the other hand. the size of the colony is largely dependent on The frequency and timing of allograft fusion. They are characteristically found on soft substrates. often as dense mono specific thickets. The mode of colony formation in halysitids is probably species-specific and results in the adaptation to substrates. * Colony development, halysitid corals, Anticosti Island. Gotland . 相似文献
36.
CHARLES B. BEARD JERRY F. BUTLER JAMES J. BECNEL 《The Journal of eukaryotic microbiology》1990,37(2):90-99
A new species of microsporidium, Nolleria pulicis, is described and named here from the cat flea, Ctenocephalides felis. The genus Nolleria is created and placed within the family Chytridiopsidae. The family is slightly modified to accommodate certain features of intracellular development seen in N. pulicis, which is otherwise very similar to other species in the family Chytridiopsidae. Sporulation is described from ultrastructural analysis of infected midgut epithelial cells of adult C. felis. The term “multiple division by vacuolation” is proposed for describing sporogony as it occurs in this species and certain related species of microsporidia. The probable mode of transmission and apparent absence of merogony are discussed. 相似文献
37.
ABSTRACT. A new species of Amblyospora , a parasite found in wild populations of the predacious Australian mosquito Culex halifaxi , was investigated with light and electron microscopy. This species was found to be heterosporous with two concurrent sporulation sequences in the host larvae, both arising from diplokaryotic meronts and ending with haploid spores. One sequence was dominant and involved meiosis to produce eight thick-walled, broadly oval meiospores in a sporophorous vesicle (SV). The other sequence involved nuclear dissociation to produce lanceolate, thin-walled spores in a subpersistent SV. Horizontal transmission to the mosquito host, by one or both of two distinctly different pathways (one via an intermediate host, the other by cannibalism of infected individuals) and by vertical transmission, are postulated but have not been demonstrated. A new species, Amblyospora trinus , is proposed and its affinities to other heterosporous microsporidia in mosquitoes are discussed. 相似文献
38.
The reproduction of raptors strongly depends on food resources. It is unclear whether predators experience superabundant food during cyclic peaks of prey populations. In order to test this hypothesis, four pairs of Great Horned Owls Bubo virginianus with two young were subjected to brood size manipulations during high densities of cyclic Snowshoe Hare Lepus americanus populations in southwestern Yukon, Canada. Broods older than 35 days were temporarily enlarged by one, and then by two, young. No effects were observed when one owlet was added, but the addition of two young resulted in significant weight losses in manipulated broods. Females with enlarged broods moved farther from their nest sites at night, presumably reflecting increased hunting effort, and also spent less time near the nest during the day. Food additions to enlarged broods returned the parental behaviour to normal. We conclude that these large predators did not experience superabundant food at this stage of the breeding season during a peak in cyclic prey. 相似文献
39.
40.
Formaldehyde treated cherry mottle leaf virus (ChMLV) and the isolated coat protein were used successfully for the production of polyclonal and monoclonal antibodies. The monoclonal antibodies had a titre of 1:51 200 and consisted of IgG1 and IgG2. The antibodies reacted with all 11 isolates of ChMLV, from five locations in Canada and the USA, included in this study. Several serological procedures were assessed to compare their sensitivity for detecting ChMLV. Plate-trapped antigen ELISA (PTA-ELISA) and dot-blot immunobinding assay (DBIA), using virus specific MAbs, were the most sensitive tests in this study. Triple antibody sandwich ELISA (TAS-ELISA) and Western blot were found to be less sensitive. Dilution of the samples appeared to increase the sensitivity of both PTA-ELISA and Western blot detection. Young leaves and flowers of Prunus avium were the best tissue for detecting the virus which could also be detected in the fruit and leaves of P. tomentosa. April and May were optimal for detection of the virus in the field, whereas both April to May and August to September were optimal for screenhouse-grown plants. 相似文献