Major histocompatibility complex genes (MHC), a gene cluster that controls the immune response to parasites, are regarded as an important determinant of mate choice. However, MHC‐based mate choice studies are especially rare for endangered animals. The giant panda (Ailuropoda melanoleuca), a flagship species, has suffered habitat loss and fragmentation. We investigated the genetic variation of three MHC class II loci, including DRB1, DQA1, and DQA2, for 19 mating‐pairs and 11 parent‐pairs of wild giant pandas based on long‐term field behavior observations and genetic samples. We tested four hypotheses of mate choice based on this MHC variation. We found no supporting evidence for the MHC‐based heterosis, genetic diversity, genetic compatibility and “good gene” hypotheses. These results suggest that giant pandas may not use MHC‐based signals to select mating partners, probably because limited mating opportunities or female‐biased natal dispersal restricts selection for MHC‐based mate choice, acknowledging the caveat of the small sample size often encountered in endangered animal studies. Our study provides insight into the mate choice mechanisms of wild giant pandas and highlights the need to increase the connectivity and facilitate dispersal among fragmented populations and habitats. 相似文献
Pollen morphology of 10 species of Hemerocallis was investigated with LM and SEM. In addition to pollen with reticulate sexine, a new verrucate sexine pattern is found in three Chinese endemic species, H. plicata, H. forrestii and H. nana . Between the two typical sexine patterns, there are transitional variants. Also, a new pollen shape, boat-shaped-elliptic, is observed exclusively in H. nana , besides-oblong shape in other species. Phylogenetically, the common reticulate sexine pattern would be more primitive than the verrucate one. The typical reticulate sexine pattern would be basic, from which transitional variants would have derived and finally led to the typical verrucate pattern. Similarly, the common boat-shaped-oblong pollen would be more primitive than the -elliptic one, from which the latter would have derived during phylogenetic development. 相似文献
Glutathione (GSH) and GSH‐related enzymes constitute the most important defense system that protects cells from free radical, radiotherapy, and chemotherapy attacks. In this study, we aim to explore the potential role and regulatory mechanism of the GSH redox cycle in drug resistance in glioblastoma multiforme (GBM) cells. We found that temozolomide (TMZ)‐resistant glioma cells displayed lower levels of endogenous reactive oxygen species and higher levels of total antioxidant capacity and GSH than sensitive cells. Moreover, the expression of glutathione reductase (GSR), the key enzyme of the GSH redox cycle, was higher in TMZ‐resistant cells than in sensitive cells. Furthermore, silencing GSR in drug‐resistant cells improved the sensitivity of cells to TMZ or cisplatin. Conversely, the over‐expression of GSR in sensitive cells resulted in resistance to chemotherapy. In addition, the GSR enzyme partially prevented the oxidative stress caused by pro‐oxidant L‐buthionine ‐sulfoximine. The modulation of redox state by GSH or L‐buthionine –sulfoximine regulated GSR‐mediated drug resistance, suggesting that the action of GSR in drug resistance is associated with the modulation of redox homeostasis. Intriguingly, a trend toward shorter progress‐free survival was observed among GBM patients with high GSR expression. These results indicated that GSR is involved in mediating drug resistance and is a potential target for improving GBM treatment.
Russian Journal of Bioorganic Chemistry - Porphyromonas gingivalis is the main pathogen of periodontitis. The purpose of this study was to analyze the effect of p62 protein on P. gingivalis-induced... 相似文献
China has over 1,200 species of native orchids in nearly 173 genera. About one fourth of native species are of horticultural
merit. Some species are of Chinese medicinal value. In fact, the demand on orchid species with high Chinese medicinal values
such as Gastrodia elata, Dendrobium offcinale, along with demands on species of cultural importance, such as those in the genus of Cymbidium, is a major factor causing wild populations to diminish and in some cases, drive wild populations to the brink of extinction.
These market demands have also driven studies on the role of mycorrhizal fungi in orchid seed germination, seedling and adult
growth, and reproduction. Most of these mycorrhizal studies of Chinese orchids, however, are published in Chinese, some in
medical journals, and thus overlooked by the mainstream orchid mycorrhizal publications. Yet some of these studies contained
interesting discoveries on the nature of the mycorrhizal relationships between orchids and fungi. We present a review of some
of these neglected publications. The most important discovery comes from the mycorrhizal studies on G. elata, in which the researchers concluded that those fungi species required to stimulate seed germination are different from those
that facilitate the growth of G. elata beyond seedling stages. In addition, presence of the mycorrhizal fungi associated with vegetative growth of post-seedling
G. elata hindered the germination of seeds. These phenomena were unreported prior to these studies. Furthermore, orchid mycorrhizal
studies in China differ from the mainstream orchid studies in that many epiphytic species (in the genus of Dendrobium, as medicinal herbs) were investigated as well as terrestrial orchids (mostly in the genus Cymbidium, as traditional horticultural species). The different responses between epiphytic and terrestrial orchid seeds to fungi derived
from roots suggest that epiphytic orchids may have a more general mycorrhizal relationship with fungi than do terrestrial
orchid species during the seed germination stage. To date, orchid mycorrhizal research in China has had a strongly commercial
purpose. We suggest that this continuing research on orchid mycorrhizal relationships are a solid foundation for further research
that includes more rare and endangered taxa, and more in-situ studies to assist conservation and restoration of the endangered
orchids. Knowledge on the identities and roles of mycorrhizal fungi of orchids holds one of the keys to successful restoration
and sustainable use of Chinese orchids. 相似文献
Antagonistic coevolution between host and parasite drives species evolution. However, most of the studies only focus on parasitism adaptation and do not explore the coevolution mechanisms from the perspective of both host and parasite. Here, through the de novo sequencing and assembly of the genomes of giant panda roundworm, red panda roundworm, and lion roundworm parasitic on tiger, we investigated the genomic mechanisms of coevolution between nonmodel mammals and their parasitic roundworms and those of roundworm parasitism in general. The genome-wide phylogeny revealed that these parasitic roundworms have not phylogenetically coevolved with their hosts. The CTSZ and prolyl 4-hydroxylase subunit beta (P4HB) immunoregulatory proteins played a central role in protein interaction between mammals and parasitic roundworms. The gene tree comparison identified that seven pairs of interactive proteins had consistent phylogenetic topology, suggesting their coevolution during host–parasite interaction. These coevolutionary proteins were particularly relevant to immune response. In addition, we found that the roundworms of both pandas exhibited higher proportions of metallopeptidase genes, and some positively selected genes were highly related to their larvae’s fast development. Our findings provide novel insights into the genetic mechanisms of coevolution between nonmodel mammals and parasites and offer the valuable genomic resources for scientific ascariasis prevention in both pandas. 相似文献