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991.
992.
Habitat fragmentation is known to generally reduce the size of plant populations and increase their isolation, leading to
genetic erosion and increased between-population genetic differentiation. In Flanders (northern Belgium) Primula vulgaris is very rare and declining. Populations have incurred strong fragmentation for the last decades and are now restricted to
a few highly fragmented areas in an intensively used agricultural landscape. Previous studies showed that small populations
of this long-lived perennial herb still maintained high levels of genetic variation and low genetic differentiation. This
pattern can either indicate recent gene flow or represent historical variation. Therefore, we used polymorphic microsatellite
loci to investigate genetic variation and structure in adult (which may still reflect historical variation) and seedling (recent
generation, thus affected by current processes) life stages. The recent generation (seedlings) showed a significant loss of
observed heterozygosity (H
o) together with lower expected heterozygosity (H
e), a trend for higher inbreeding levels (F
IS) and higher differentiation (F
ST) between populations compared to the adult generation. This might result from (1) a reduction in effective population size,
(2) higher inbreeding levels in the seedlings, (3) a higher survival of heterozygotes over time due to a higher fitness of
heterozygotes (heterosis) and/or a lower fitness of homozygotes (inbreeding depression), (4) overlapping generations in the
adult life stage, or (5) a lack of establishment of new (inbred) adults from seedlings due to degraded habitat conditions.
Combining restoration of both habitat quality and gene flow between populations may be indispensable to ensure a sustainable
conservation of fragmented populations. 相似文献
993.
Binu Timsina Maan B. Rokaya Zuzana Münzbergová Pavel Kindlmann Bikram Shrestha Bishnu Bhattarai Bhakta B. Raskoti 《Biodiversity and Conservation》2016,25(13):2803-2819
Associations between epiphytes and their hosts are among the main factors affecting the biodiversity and distribution of epiphytes. While several previous studies explored the association between epiphyte diversity and host characteristics, very little is known about the generality of such associations at larger spatial scales. We aim to explore the associations between diversity and distribution of epiphytic orchids and host characteristics in different localities in Nepal. Epiphytic orchids and their hosts were recorded along the transects in total of 23,539 host individuals. To describe the diversity of orchids in the different localities, a rarefaction function was used. Univariate and multivariate analyses were carried out to explore the associations with locality, host characteristics, and their interactions with locality. In total, we recorded 141 species of orchids growing on 192 host species. The five localities significantly differed in orchid diversity and abundance. The number of orchid individuals per host species significantly increased with increasing number of host individuals. Species richness, abundances, occupancy of orchid species on host species and composition of orchids varied across the localities. Species richness and abundance was significantly higher on hosts in the higher strata and differed between families of host species. Abundance was higher on evergreen hosts. Composition of orchid communities are also associated with host characteristics, such as habit (shrub/tree/climber), bark texture, nature (deciduous/evergreen) and the plant families of host species. This study revealed a high diversity of epiphytic orchids in the localities studied and strong associations between the orchids and their hosts. Future studies looking at the relationships between epiphyte communities and host characteristics need to identify relationships at a wider scale in order to determine whether they are really general rather than site-specific. 相似文献
994.
Sara Diana Leonhardt Andreas Simon Brandstaetter Christoph Johannes Kleineidam 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(9):993-1000
Ants use cuticular hydrocarbons (CHC-profiles) as multicomponent recognition cues to identify colony members (nestmates).
Recognition cues (label) are thought to be perceived during ant–ant encounters and compared to a neuronal template that represents
the colony label. Over time, the CHC-profile may change, and the template is adjusted accordingly. A phenotype mismatch between
label and template, as happens with CHC-profiles of foreign workers (non-nestmates), frequently leads to aggressive behavior.
We investigated the template reformation in workers of the carpenter ant Camponotus floridanus by masking their antennae with postpharyngeal gland (PPG) extracts from nestmates or non-nestmates. The behavioral response
of manipulated workers encountering unmanipulated workers was measured independently after 2 and after 15 h. After 2 h of
incubation, workers treated with either of the two PPG-extracts showed low aggression towards nestmates and high aggression
towards non-nestmates. In contrast, after 15 h of incubation, workers treated with non-nestmate PPG-extract showed low aggression
towards both nestmates and non-nestmates. The slow (>2 h) adjustment of the template indicates a reformation localized in
the central nervous system rather than in chemosensory neurons. In addition, our data show that template adjustment to a new
CHC-profile does not impair the assessment of the old CHC-profile as nestmate label. 相似文献
995.
Ping Xu Xinhua Cai Wenbo Zhang Yana Li Peiyong Qiu Dandan Lu Xiaoyang He 《Apoptosis : an international journal on programmed cell death》2016,21(10):1125-1143
The objective of our study was to assess the radioprotective effect of flavonoids extracted from Rosa roxburghii Tratt (FRT) and investigate the role of Bcl-2(Ca2+)/Caspase-3/PARP-1 pathway in radiation-induced apoptosis. Cells and mice were exposed to 60Co γ-rays at a dose of 6 Gy. The radiation treatment induced significant effects on tissue pathological changes, apoptosis, Ca2+, ROS, DNA damage, and expression levels of Bcl-2, Caspase-3 (C-Caspase-3), and PARP-1. The results showed that FRT acted as an antioxidant, reduced DNA damage, corrected the pathological changes of the tissue induced by radiation, promoted the formation of spleen nodules, resisted sperm aberration, and protected the thymus. FRT significantly reduced cell apoptosis compared with the irradiation group. The expression of Ca2+ and C-Caspase-3 was decreased after FRT treatment compared with the radiation-treated group. At the same time, expression of prototype PARP-1 and Bcl-2 increased, leading to a decrease in the percentage of apoptosis cells in FRT treatment groups. We conclude that FRT acts as a radioprotector. Apoptosis signals were activated via the Bcl-2(Ca2+)/Caspase-3/PARP-1 pathway in irradiated cells and FRT inhibited this pathway of apoptosis by down-regulation of C-Caspase-3 and Ca2+ and up-regulation of prototype PARP-1 and Bcl-2. 相似文献
996.
Huipeng Liang Liguo Yin Yahao Zhang Cong Chang Wenxue Zhang 《Annals of microbiology》2018,68(2):111-122
Paocai is a traditional Chinese fermented food and typically produced via spontaneous fermentation. We have investigated the microbial community utilized for the fermentation of industrialized Qingcai paocai using the combination of Illumina MiSeq sequencing, PCR-mediated denaturing gradient gel electrophoresis (PCR-DGGE) and quantitative PCR (qPCR) assay. Three main phyla, namely Firmicutes, Proteobacteria and Bacteroidetes, were identified by both MiSeq sequencing and PCR-DGGE. The dominant genera observed in the fermentation were Lactobacillus, Pseudomonas, Vibrio and Halomonas. Most genera affiliated with Proteobacteria or Bacteroidetes were detected more often during the earlier part of the fermentation, while Lactobacillus (affiliated with Firmicutes) was dominant during the later fermentation stages. Fungal community analysis revealed that Debaryomyces, Pichia and Kazachstania were the main fungal genera present in industrialized Qingcai paocai, with Debaryomyces being the most dominant during the fermentation process. The quantities of dominant genera Lactobacillus and Debaryomyces were monitored using qPCR and shown to be 109–1012 and 106–1010 copies/mL, respectively. During the later fermentation process of industrialized Qingcai paocai, Lactobacillus and Debaryomyces were present at 1011 and 108 copies/mL, respectively. These results facilitate further understanding of the unique microbial ecosystem during the fermentation of industrialized Qingcai paocai and guide future improvement of the fermentation process. 相似文献
997.
Zhi-Yong Zhang Feng-Ling Fu Lin Gou Han-Guang Wang Wan-Chen Li 《Journal of Plant Biology》2010,53(4):297-305
Maize dwarf mosaic virus (MDMV) is a widespread pathogenic virus that causes serious loss of yield in maize (Zea mays). RNA interference (RNAi) triggered by hairpin RNA (hpRNA) transcribed from a transgenic inverted-repeat sequence is an effective
way to defend against viruses in plants. In this study, an hpRNA expression vector containing a sense arm and an antisense
arm of 150 bp separated by an intron of the maize actin gene was constructed to target the P1 protein (protease) gene of MDMV
and used to transform Agrobacterium tumefaciens strain EHA105. The transformed Agrobacterium strain was used to transform maize embryonic calli isolated from immature embryos by an improved culture technique. In all,
46 plants were regenerated after stringent hygromycin B selection, and 18 of them were certified to be positive by PCR amplification.
Of these positive plants, 13 were grown to produce offspring, and nine were identified by Southern blotting to have the transgene
integrated with one or two copies. The resistance of three T2 lines was evaluated in a field trial of dual MDMV inoculation in two environments and was found to be improved compared with
the non-transformed control. The disease indexes of the transgenic plant lines h2, 13, and h1 were not significantly different
from the highly resistant control line H9-21. The viral titers of the inoculated plants were detected by double antibody sandwich
enzyme-linked immunosorbent assay (DAS-ELISA), and the result was in accord with the resistance evaluated in the field trial.
The addition of uniconazole S3307 (0.25 mg l−1) and ABT root-promoting powder (0.5 mg l−1) showed a significant improvement of hardening in regenerated plantlets, which were stronger and generated a better fibrous
root system than the control. This improvement could facilitate the transgenic operation of maize. 相似文献
998.
999.
Bevan KS Chung Suresh Selvarasu Andrea Camattari Jimyoung Ryu Hyeokweon Lee Jungoh Ahn Hongweon Lee Dong-Yup Lee 《Microbial cell factories》2010,9(1):50
Background
Pichia pastoris has been recognized as an effective host for recombinant protein production. A number of studies have been reported for improving this expression system. However, its physiology and cellular metabolism still remained largely uncharacterized. Thus, it is highly desirable to establish a systems biotechnological framework, in which a comprehensive in silico model of P. pastoris can be employed together with high throughput experimental data analysis, for better understanding of the methylotrophic yeast's metabolism. 相似文献1000.
Bocher BT Agler MT Garcia ML Beers AR Angenent LT 《Journal of industrial microbiology & biotechnology》2008,35(5):321-329
Many beer breweries use high-rate anaerobic digestion (AD) systems to treat their soluble high-strength wastewater. Biogas
from these AD systems is used to offset nonrenewable energy utilization in the brewery. With increasing nonrenewable energy
costs, interest has mounted to also digest secondary residuals from the high-rate digester effluent, which consists of yeast
cells, bacteria, methanogens, and small (hemi)cellulosic particles. Mesophilic (37 °C) and thermophilic (55 °C) lab-scale,
low-rate continuously-stirred anaerobic digestion (CSAD) bioreactors were operated for 258 days by feeding secondary residuals
at a volatile solids (VS) concentration of ∼40 g l−1. At a hydraulic retention time (HRT) of 15 days and a VS loading rate of 2.7 g VS l−1 day−1, the mesophilic bioreactor showed an average specific volumetric biogas production rate of 0.88 l CH4 l−1 day−1 and an effluent VS concentration of 22.2 g VS l−1 (43.0% VS removal efficiency) while the thermophilic bioreactor displayed similar performances. The overall methane yield
for both systems was 0.21 l CH4 g−1 VS fed and 0.47–0.48 l CH4 g−1 VS removed. A primary limitation of thermophilic digestion of this protein-rich waste is the inhibition of methanogens due
to higher nondissociated (free) ammonia (NH3) concentrations under similar total ammonium (NH4
+) concentrations at equilibrium. Since thermophilic AD did not result in advantageous methane production rates or yields,
mesophilic AD was, therefore, superior in treating secondary residuals from high-rate AD effluent. An additional digester
to convert secondary residuals to methane may increase the total biogas generation at the brewery by 8% compared to just conventional
high-rate digestion of brewery wastewater alone.
JIMB-2008: BioEnergy—Special issue. 相似文献