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41.
Dozens of studies have documented that brood parasites are well adapted to a brood parasitic lifestyle but not all parasitism events are successful. Co-evolution between brood parasites and their hosts is a dynamic process so it is reasonable to expect that a female brood parasite may commit errors during egg deposition by laying her eggs outside the laying period of the host, with consequent impacts on her fitness. Using an extensive dataset from a long-term study, we evaluated egg-laying patterns and errors related to the timing of egg-laying in the Common Cuckoo Cuculus canorus (hereafter ‘Cuckoo’). Specifically, we tested whether the Cuckoo avoids laying before or on the day of host clutch initiation to reduce the risk of rejection of parasitic eggs, whether laying errors will be more frequent in periods with a lack of active host nests, and whether the laying errors will be more frequent in periods with intense Cuckoo parasitism and a consequent lack of suitable host nests. We found that about one-third of Cuckoo eggs were laid on the host clutch initiation day or 1 day before, and the percentage of Cuckoo eggs laid decreased thereafter. Surprisingly, the probability of Cuckoo egg acceptance by the hosts was not affected by the egg-laying stage of the host clutch. Errors in the timing of egg-laying with fatal consequences (i.e. those precluding Cuckoo hatching because of laying in incubated or deserted clutches) were recorded in about 5% of cases. Only laying date of a Cuckoo egg had a significant effect on the probability of errors, which increased during the breeding season. This may be related to the higher number of deserted and incubated host nests at the site at the end of the breeding season. Errors in egg-laying may be attributed to young and inexperienced females but also impaired body condition or intraspecific competition may cause this behaviour. Future studies, which will test these possible explanations, will help to understand better the mechanism of co-evolutionary arms races and differences between host specialist and generalist brood parasites in various host–parasite systems. 相似文献
42.
Jouni Aspi Eeva Roininen Jukka Kiiskilä Minna Ruokonen Ilpo Kojola Leo Bljudnik Pjotr Danilov Samuli Heikkinen Erkki Pulliainen 《Conservation Genetics》2009,10(4):815-826
We examined the genetic diversity and structure of wolf populations in northwestern Russia. Populations in Republic of Karelia
and Arkhangelsk Oblast were sampled during 1995–2000, and 43 individuals were genotyped with 10 microsatellite markers. Moreover,
118 previously genotyped wolves from the neighbouring Finnish population were used as a reference population. A relatively
large amount of genetic variation was found in the Russian populations, and the Karelian wolf population tended to be slightly
more polymorphic than the Arkhangelsk population. We found significant inbreeding (F = 0.094) in the Karelian, but not in the Arkhangelsk population. The effective size estimates of the Karelian wolf population
based on the approximate Bayesian computation and linkage disequilibrium methods were 39.9 and 46.7 individuals, respectively.
AMOVA-analysis and exact test of population differentiation suggested clear differentiation between the Karelian, Arkhangelsk
and Finnish wolf populations. Indirect estimates of gene flow based on the level of population differentiation (ϕ
ST
= 0.152) and frequency of private alleles (0.029) both suggested a low level of gene flow between the populations (Nm = 1.4 and Nm = 3.7, respectively). Assignment analysis of Karelian and Finnish populations suggested an even lower number of recent migrants
(less than 0.03) between populations, with a larger amount of migration from Finland to Karelia than vice versa. Our findings
emphasise the role of physical obstacles and territorial behaviour in creating barriers to gene flow between populations in
relatively limited geographical areas, even in large-bodied mammalian species with long-distance dispersal capabilities and
an apparently continuous population structure. 相似文献
43.
44.
45.
《International journal for parasitology》2021,51(11):893-898
The early-phase migration dynamics of Echinococcus multilocularis in the intermediate hosts remain largely unknown. We compared the parasite burden in the intestine, liver and faeces of DBA/2 and C57BL/6 mouse strains using parasite-specific quantitative PCR. Our results indicated that the parasites invaded mainly from the middle segments of the small intestine and completed migration to the liver within 24 h p.i. C57BL/6 mice had lower parasite DNA burdens in the intestine and liver but higher in the faeces than DBA/2 mice, suggesting that parasite invasion of the intestine may be a critical stage regulating susceptibility to E. multilocularis infection in mice. 相似文献
46.
Sandra Kranich Kirsten Hattermann Aljona Specht Ralph Lucius Rolf Mentlein 《Neurochemistry international》2009,55(8):747-753
Neuronal and vascular cells share common chemical signals. Vascular endothelial growth factor (VEGF)-C and -D and their receptor VEGFR-3/Flt-4 mediate lymphangiogenesis, but they occur also in the brain. Quantitative RT-PCR of mouse brain tissues and cultivated cells showed that the VEGFR-3 gene is highest transcribed in postnatal brain and in glial precursor cells whereas VEGF-C and -D are variably produced by different neuronal and glial cells. In neurospheres (neural stem cells) VEGFR-3 was induced by differentiation with platelet-derived growth factor (PDGF). In functional studies with an A2B5- and nestin-positive, O4-negative murine glial precursor cell line, VEGF-C and -D stimulated phosphorylation of the kinases Erk1/2; this signal transduction was inhibited by UO126. Both peptides induced the proliferation of glial precursor cells which could be inhibited by UO126. Furthermore, VEGF-D considerably enhanced their migration into an open space in a wound-healing assay. These results show that VEGF-C/-D together with its receptor VEGFR-3 provides an auto-/paracrine growth and chemotactic system for glial precursors in the developing brain. 相似文献
47.
48.
Involvement of Matrix Metalloproteinases on the Inhibition of Cells Invasion and Migration by Emodin in Human Neuroblastoma SH-SY5Y Cells 总被引:1,自引:0,他引:1
Hsu-Feng Lu Kuang-Chi Lai Shu-Chun Hsu Hui-Ju Lin Chao-Lin Kuo Ching-Lung Liao Jai-Sing Yang Jing-Gung Chung 《Neurochemical research》2009,34(9):1575-1583
Emodin (1,3,8-trihydroxy-6-methylanthaquinone), an active component present in the root and rhizome of Rheum palmatum L. (Polygonaceae) has anti-bacterial, anti-tumor, diuretic and vasorelaxant effects. However, its mechanism of action on
the cell migration and invasion of human neuroblastoma cancer SH-SY5Y cells is not fully understood. In this study, firstly,
the effects of emodin on the percentage of viable cells were examined by using MTT assay and it was found that emodin induced
dose-and time-dependent inhibition in human neuroblastoma SH-SY5Y cells. Second, the effects of emodin on the migration and
invasion of SH-SY5Y cells were examined by using wound assay and matrigel counting and the results showed that emodin suppressed
the migration and invasion of SH-SY5Y cells. Third, we examined the effect of emodin on the levels of associated proteins
by using Western blotting and the results indicated that emodin inhibited the levels of GRB2, RhoA, HIF-1α, VEGF, FAK, iNOS,
COX2, p-p38, p-c-jun, MMP2, MMP9 and MMP7 but promoted the levels of PKC, PI3K, MEKK3 and NF-κB p65 that led to the inhibition
of migration and invasion of SH-SY5Y cells in vitro. 相似文献
49.
Cory T. Miller Kaylin Beck Brooke Meade Xiaoqin Wang 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(8):783-789
Studies of primate vocal communication systems have generally focused on vocalizations and the information they convey to
conspecifics. But the vocalizations are not the only sources of information. Aspects of each species vocal behaviors are likely
to be communicatively rich as well. During vocal interactions, for example, the latency delay between the calls could communicate
an important message to the signal receiver, such as an interest and willingness to socialize. Here we employed novel, interactive
playback software to address this issue in the antiphonal calling behavior of common marmosets. In these experiments, we parametrically
varied the latency delay of antiphonal call stimuli and measured its effects on subjects’ resultant vocal behavior. Results
showed that marmosets produced successively fewer antiphonal call responses during test conditions with increasing latency
delays. Moreover, although subjects produced significantly more antiphonal than spontaneous calls in conditions with antiphonal
call timing delays up to 9 s, a longer delay resulted in a significant decline in calling. These data suggest that antiphonal
call timing is a salient cue for maintaining antiphonal calling interactions and may be used by marmosets to determine whether
a subsequent call is produced in response to or independently of their own. 相似文献
50.
Two outdoor shiitake (Lentinula edodes) cultivation experiments, established in Missouri USA in 1999 and 2000, produced mushrooms in 2000–2005. We examined shiitake production in response to substrate species, inoculum form, inoculum strain, and inoculation timing, using total mushroom weight per log as the primary response variable with log characteristics as covariates. The significantly greater mushroom weight produced by sugar maple logs compared with white or northern red oak was attributable to the higher proportion of undiscolored wood volume in the maple logs, rather than to bark thickness or log diameter. The “wide temperature range” shiitake strain produced significantly greater yield compared with the “warm” or “cold” weather strains. Both the wide-range and warm-weather strains were stimulated to fruit by significant rain events, while the cold-weather strain was responsive to temperature. Inoculation with sawdust spawn gave significantly greater yield than colonized wooden dowels or pre-packaged “thimble” plug inoculum. The second and third full years following inoculation were the most productive. 相似文献