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41.
42.
OLIVIA RICKENBACH MARTIN U. GRÜEBLER MICHAEL SCHAUB ANDREIA KOLLER BEAT NAEF‐DAENZER LUC SCHIFFERLI 《Ibis》2011,153(3):531-542
Many farmland‐breeding wader species have declined across Europe, probably due to reductions in reproductive output caused by high nest losses as a result of agriculture or predation, or low chick survival between hatching and fledging. Most studies have focused on nest failures, and the factors affecting post‐hatching survival of chicks are poorly known. In an experimental approach, we fenced parts of the arable foraging areas of Northern Lapwing Vanellus vanellus families to quantify chick survival simultaneously in the presence and absence of ground predators. Lapwing chicks were radiotagged to estimate survival probabilities by daily locations, applying multistate capture–recapture models. During the night, chick survival was considerably lower outside fenced plots than within. During the day, chick survival was higher than at night and did not differ between protected and unprotected plots. This suggests that nocturnal ground predators such as Red Foxes Vulpes vulpes were responsible for a significant proportion of chick mortality. Cumulative survival probability from hatching to fledging was 0.24 in chicks within fenced plots, but virtually zero in chicks outside fenced plots. In farmland, temporary electric fences can be effective in minimizing the impact of ground predators and offer a promising short‐term method to increase fledging success of precocial birds. 相似文献
43.
STEVE J. UPTON WILLIAM L. CURRENT SUSAN M. BARNARD JOHN V. ERNST 《The Journal of eukaryotic microbiology》1984,31(2):293-297
In vitro excystation of sporozoites of the heteroxenous coccidian Caryospora simplex Léger, 1904 (Apicomplexa: Eimeriorina) is described. Sporocysts freed mechanically from oocysts released a maximum of 51% of their sporozoites within 45 min at 25°C and a maximum of 74% within 20 min at 37°C when incubated in a 0.25% (w/v) trypsin–0.75% (w/v) sodium taurocholate (bile salt) excystation solution. At emergence from sporocysts, sporozoites were weakly motile then became highly active after about 2 min in excystation solution. Sporozoites within sporocysts exposed to bile salt only became highly motile within 25 min at 25°C and within 15 min at 37°C but did not excyst. When exposed only to trypsin at the above temperatures, the Stieda body dissolved; the substieda body remained intact, and the sporozoites exhibited only limited motility within sporocysts; only a few excysted. Intact, sporulated oocysts incubated at 25° or 37°C in 0.02 M cysteine-HC1 and a 50% CO2 atmosphere for 18 h had no morphologic changes in the oocyst wall. Further incubation of these intact oocysts in excystation solution for 30 min at 37°C caused neither motility of sporozoites within sporocysts nor excystation. Grinding oocysts for 30 sec in a motor-driven, teflon-coated tissue grinder caused motility of some sporozoites within sporocysts but did not result in excystation. 相似文献
44.
ERNST KUECHLER 《Nature: New biology》1971,234(50):216-218
FORMATION of the E. coli initiation complex between ribosomal subunits, natural messenger RNA and formyl-methionyl-tRNAf (fMet-tRNAf) requires the presence of initiation factors and GTP1–3. In the binding reaction, GTP can be replaced by an analogue, guanylyl-5′-methylene-diphosphonate (GMP-PCP), but the complex does not then react with puro-mycin. Hydrolysis of GTP is therefore required for the formation of an active initiation complex able to carry out peptide bond formation4. 相似文献
45.
LARRY D. HENDRICKS JOHN V. ERNST CHARLES H. COURTNEY CLARENCE A. SPEER 《The Journal of eukaryotic microbiology》1979,26(1):39-43
Synopsis.
Hammondia pardals sp. n. (Eimeriorina: Sarcocystidae) from Panama Canal Zone is described as an obligate heteroxenous coccidian, with felids as the final host and laboratory mice as the experimental intermediate host. Ovoid oocysts. measuring 40.8 (36–46) × 28.5 (25–35) m. are shed unsporulated. Oocysts were infective only for the intermediate host. the laboratory mouse, Mus musculus , and the intracellular cysts were infective only for felids. Attempted passage of tissue cysts from mouse to mouse was unsuccessful.
Mice fed 5 × 104 sporulated oocysts were found to harbor small intracellular cysts, 13–16 × 10–15 m, in the mesenteric lymph nodes, lungs, and intestinal submucosa 15 days postinfection. The meronts in these early cysts were stubby and measured 3 × 6 m. The prepatent period in the felids was 5 to 8 days and the patent period 5–13 days. Experimental infections of definitive hosts were successful with 6/6 domestic laboratory-reared kittens, Felis catus ; 5/5 ocelots, F. pardalis ; and 1/1 jaguarundi, F. yagouaroundi. None of the exposed raccoons, Procyon lotor , shed oocysts. 相似文献
Hammondia pardals sp. n. (Eimeriorina: Sarcocystidae) from Panama Canal Zone is described as an obligate heteroxenous coccidian, with felids as the final host and laboratory mice as the experimental intermediate host. Ovoid oocysts. measuring 40.8 (36–46) × 28.5 (25–35) m. are shed unsporulated. Oocysts were infective only for the intermediate host. the laboratory mouse, Mus musculus , and the intracellular cysts were infective only for felids. Attempted passage of tissue cysts from mouse to mouse was unsuccessful.
Mice fed 5 × 10
46.
JOHN V. ERNST EMILY C. OAKS J. ROBERT SAMPSON 《The Journal of eukaryotic microbiology》1970,17(3):453-455
SYNOPSIS The oocysts of 2 new species of Eimeria are described from heteromyid rodents. The subspherical to ellipsoidal cocysts of Eimeria reedi from Perognathus formosus averaged 22.6 by 20.8 μ. An ellipsoidal polar granule was present. The oocyst residuum was a single globule about 8 μ in diameter. The ovoid sporocysts averaged 10.9 by 7.7 μ and had a residuum of 6-12 granules. A Stieda body and substiedal body were present in the sporocysts. Eimeria chobotari oocysts, from Dipodomys merriami and D. microps , were ellipsoidal to ovoid and averaged 47.7 by 35.2 μ. No polar granule was seen. The large oocyst residuum consisted of several granules of various sizes. The ovoid sporocysts averaged 15.8 by 11.3 μ and had a residuum of many small granules. A Stieda body and substiedal body were present in the sporocysts. 相似文献
47.
Canonical correlation analysis measures the linear relationshipbetween two random vectors X1 and X2 as the maximum correlationbetween linear combinations of X1 and linear combinations ofX2. Several generalisations of canonical correlation analysisto k2 random vectors X1 ..., Xk have been proposed in the literature(Kettenring, 1971, 1985), based on the principle of maximisingsome generalised measure of correlation. In this paper we proposean alternative generalisation, called common canonical variates,based on the assumption that the canonical variates have thesame coefficients in all k sets of variables. This generalisationis applicable in situations where all Xi have the same dimension.We present normal theory maximum likelihood estimation of commoncanonical variates, and illustrate their use on a morphometricdata set. 相似文献
48.
The past decades have been exciting ones for ornithologists interested in avian macrosystematics with many new ideas being proposed for consideration and further study. But this excitement should not blind ornithologists to the important distinction between the provisional classifications proposed by specialists in macrosystematics, no matter how convincing they may appear at first glance, and the standard sequence needed to maintain optimal communication among all students of avian biologists. An excellent standard sequence for Recent birds exists in Peters' Check-list . We urge that all ornithologists, authors and editors use this sequence until the time arrives, as it undoubtedly will, when enough is known about avian relationships to permit agreement on a new and better standard sequence. 相似文献
49.
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