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991.
David L. Slager Kevin L. Epperly Renee R. Ha Sievert Rohwer Chris Wood Caroline Van Hemert John Klicka 《Molecular ecology》2020,29(5):956-969
Most species and therefore most hybrid zones have historically been defined using phenotypic characters. However, both speciation and hybridization can occur with negligible morphological differentiation. Recently developed genomic tools provide the means to better understand cryptic speciation and hybridization. The Northwestern Crow (Corvus caurinus) and American Crow (Corvus brachyrhynchos) are continuously distributed sister taxa that lack reliable traditional characters for identification. In this first population genomic study of Northwestern and American crows, we use genomic SNPs (nuDNA) and mtDNA to investigate the degree of genetic differentiation between these crows and the extent to which they may hybridize. Our results indicate that American and Northwestern crows have distinct evolutionary histories, supported by two nuDNA ancestry clusters and two 1.1%‐divergent mtDNA clades dating to the late Pleistocene, when glacial advances may have isolated crow populations in separate refugia. We document extensive hybridization, with geographic overlap of mtDNA clades and admixture of nuDNA across >900 km of western Washington and western British Columbia. This broad hybrid zone consists of late‐generation hybrids and backcrosses, but not recent (e.g., F1) hybrids. Nuclear DNA and mtDNA clines had concordant widths and were both centred in southwestern British Columbia, farther north than previously postulated. Overall, our results suggest a history of reticulate evolution in American and Northwestern crows, perhaps due to recurring neutral expansion(s) from Pleistocene glacial refugia followed by lineage fusion(s). However, we do not rule out a contributing role for more recent potential drivers of hybridization, such as expansion into human‐modified habitats. 相似文献
992.
Jong Min Lee Ha Young Chung Kyung Il Kim Ki Hyun Yoo Jeon Hwang-Bo In Sik Chung Jong-Hwa Park 《Biotechnology letters》2011,33(1):41-46
We established a bicistronic expression system using an encephalomyocarditis virus (EMCV)-derived internal ribosomal entry
site (IRES) element to generate stably transformed Drosophila
melanogaster Schneider 2 (S2) cells expressing human rotavirus Wa capsid proteins, VP2 and VP6, for the synthesis of VP2/6 double-layered
virus-like particle (DVLP). The EMCV-derived IRES permitted bicistronic translation of recombinant VP6. Recombinant VP2 and
VP6 were detected in extracellular fractions of stably transformed S2 cells. A wheel-like DVLP (diam ~ 50–55 nm) with short
spikes was produced from the extracellular fraction of stably transformed S2 cells. A bicistronic expression system using
an EMCV-derived IRES element can thus be used to express two proteins of interest in stably transformed S2 cells. The bi-or
tri-cistronic expression of recombinant VP2/6/7 using stably transformed S2 cells can also be used to produce rotavirus VLPs. 相似文献
993.
Efficient fermentation of xylose, which is abundant in hydrolysates of lignocellulosic biomass, is essential for producing
cellulosic biofuels economically. While heterologous expression of xylose isomerase in Saccharomyces cerevisiae has been proposed as a strategy to engineer this yeast for xylose fermentation, only a few xylose isomerase genes from fungi
and bacteria have been functionally expressed in S. cerevisiae. We cloned two bacterial xylose isomerase genes from anaerobic bacteria (Bacteroides stercoris HJ-15 and Bifidobacterium longum MG1) and introduced them into S. cerevisiae. While the transformant with xylA from B. longum could not assimilate xylose, the transformant with xylA from B. stercoris was able to grow on xylose. This result suggests that the xylose isomerase (BsXI) from B. stercoris is functionally expressed in S. cerevisiae. The engineered S. cerevisiae strain with BsXI consumed xylose and produced ethanol with a good yield (0.31 g/g) under anaerobic conditions. Interestingly, significant
amounts of xylitol (0.23 g xylitol/g xylose) were still accumulated during xylose fermentation even though the introduced
BsXI might not cause redox imbalance. We investigated the potential inhibitory effects of the accumulated xylitol on xylose fermentation.
Although xylitol inhibited in vitro BsXI activity significantly (K
I = 5.1 ± 1.15 mM), only small decreases (less than 10%) in xylose consumption and ethanol production rates were observed when
xylitol was added into the fermentation medium. These results suggest that xylitol accumulation does not inhibit xylose fermentation
by engineered S. cerevisiae expressing xylA as severely as it inhibits the xylose isomerase reaction in vitro. 相似文献
994.
Kim JH Kim K Youn BU Jin HM Kim JY Moon JB Ko A Seo SB Lee KY Kim N 《The Biochemical journal》2011,433(2):253-262
The MTM (myotubularin)/MTMR (myotubularin-related) protein family is comprised of 15 lipid phosphatases, of which nine members are catalytically active. MTMs are known to play a fundamental role in human physiology as gene mutations can give rise to X-linked myotubular myopathy or Charcot-Marie-Tooth disease, which manifest in skeletal muscle or in peripheral neurons respectively. Interestingly, studies have shown MTMR2 and MTMR5, two MTM family members, to be highly expressed in the testis, particularly in Sertoli and germ cells, and knockout of either gene resulted in spermatogenic defects. Other studies have shown that MTMR2 functions in endocytosis and membrane trafficking. In the testis, MTMR2 interacts and co-localizes with c-Src/phospho-Src-(Tyr?1?), a non-receptor protein tyrosine kinase that regulates the phosphorylation state of proteins at the apical ES (ectoplasmic specialization), a unique type of cell junction found between Sertoli cells and elongating/elongated spermatids. In the present review, we highlight recent findings that have made a significant impact on our understanding of this protein family in normal cell function and in disease, with the emphasis on the role of MTMs and MTMRs in spermatogenesis. We also describe a working model to explain how MTMR2 interacts with other proteins such as c-Src, dynamin 2, EPS8 (growth factor receptor pathway substrate 8) and ARP2/3 (actin-related protein 2/3) at the apical ES and the apical TBC (tubulobulbar complex; tubular-like invaginations that function in the disassembly of the apical ES and in the recycling of its components) to regulate spermiation at late stage VIII of the seminiferous epithelial cycle. 相似文献
995.
Past research has shown that aggressive behaviors can affect female reproductive outcome in nonhuman primate captive breeding programs. In this study, aggressive behaviors were recorded in a colony of pigtailed macaque monkeys (Macaca nemestrina) and related to pregnancy outcome. For 22 weeks, behavioral data were collected from nine breeding groups, consisting of zero to one male (some males were removed after a cycle of conceptions for husbandry reasons) and four to eight females. Observations included all occurrences of 11 aggressive behaviors during 15 min observation sessions, 1-3 times a week. Mean weekly aggression levels during the study period were determined for each group as well as for each pregnancy. Aggression data were summarized with Principal Components Analyses. Results indicate that pigtailed macaque aggression falls into five distinctive categories: warn, engage, threaten, pursue, and attack. Breeding groups differed in their levels of aggression, even after controlling for group size, presence of a sire, and group stability. Levels of the five aggression categories were found to affect the probability that a pregnancy ended in either a natural birth of a live infant, a clinical intervention producing a live infant, or a nonviable outcome. The predictive value of aggression was significant when clinical interventions were included as possible reproductive outcomes. Behavioral observation of captive groups could identify "risk" conditions affecting pregnancy outcome and the requirement for clinical intervention. 相似文献
996.
Lee CH Yoo KY Choi JH Park JH Kim DH Park JH Hwang IK Cho JH Kim YM Won MH 《Cellular and molecular neurobiology》2011,31(3):449-457
In this study, the authors examined the difference of phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) in
the hippocampal CA1 region (CA1) between adult and aged gerbils after 5 min of transient cerebral ischemia. Delayed neuronal
death in the CA1 of the aged group was much slower than that in the adult group after ischemia/reperfusion (I/R). pERK1/2
immunoreaction was observed in the CA1 region of the sham-operated adult gerbil. pERK1/2 immunoreactivity and protein levels
in the ischemic CA1 region of the adult group were markedly increased 4 days after I/R, and then reduced up to 10 days after
I/R. In contrast, pERK1/2 immunoreaction was hardly detected in the CA1 region of sham-operated aged gerbils, and the immunoreactivity
increased from 1 day after the ischemic insult, and still observed until 10 days post-ischemia. In addition, pERK1/2-immunoreaction
was expressed in astrocytes in the ischemic CA1 region: The expression in the ischemia-operated aged gerbils was later than
that in the ischemia-operated adult gerbils. These results indicate that different patterns of ERK1/2 immunoreactivity may
be associated with different processes of delayed neuronal death in adult and aged animals. 相似文献
997.
998.
Young Il Kim Jin-Woo Lee Mu-Hyoung Lee Seung-Won Park Byung-Nam Cho Ha Kyu Lee 《Molecular biology reports》2011,38(5):3207-3212
15-deoxy-∆12,14-prostaglandin J2 (15d-PGJ2) is an anti-inflammatory prostaglandin that plays a role in promoting the resolution of inflammation. We investigated the
effects of 15d-PGJ2 on the production of IL-8 and on the expression of Toll-like receptors (TLRs) 2 in human primary keratinocytes stimulated
with lipopolysaccharide (LPS). Cell proliferation was analyzed using the MTT assay, TLR2 and -4 mRNA expression was detected
by RT–PCR, and IL-8 production and NF-κB p65 activities were determined by ELISA. LPS and 15d-PGJ2 did not influence the proliferation rate at low concentrations (0.5 and 2.0 μM) in keratinocytes, and showed toxicity at
high concentrations (5.0 μM). LPS, compared with control, induced the expression of TLR2 mRNA, increased IL-8 production,
and enhanced NF-κB activity. 15d-PGJ2 decreased TLR2 mRNA, increased IL-8 production, and suppressed NF-κB activity. Costimulation with LPS and 15d-PGJ2, compared with LPS stimulation alone, decreased TLR2 mRNA (1.8-fold), increased IL-8 production (1.8-fold at 0.5 μM and 3.7-fold
at 2.0 μM), and inhibited NF-κB activity (3.3-fold at 0.5 μM and 5.1-fold at 2.0 μM). TLR4 mRNA was not expressed in primary
keratinocytes. These results suggest that 15d-PGJ2 suppresses TLR2 expression and that it up-regulates the production of IL-8 by inhibiting the NF-κB signaling pathway in primary
keratinocytes. Thus, 15d-PGJ2 can have both anti- and pro-inflammatory effects, and 15d-PGJ2-mediated IL-8 up-regulation is related to the mitogen-activated protein kinase (MAPK) and NF-κB signaling pathways. 相似文献
999.
Lee CH Yoo DY Park OK Park JH Yi SS Yoon YS Won MH Hwang IK 《Neurochemical research》2011,36(10):1767-1775
Newly generated neurons in the dentate gyrus differentiate into mature granule cells. In the present study, we observed the effects of adrenalectomy (ADX) and corticosterone replacement therapy (CRT) on cell death, cell proliferation and neuroblast differentiation in the subgranular zone of the hippocampal dentate gyrus (SZDG). For this, the animals received vehicle or CRT after ADX, and were sacrificed 5 or 42 days later. Plasma corticosterone levels were very low in the adrenalectomized groups, whereas CRT after ADX significant increased serum corticosterone levels at 42 days, not 5 days, after ADX. ADX induced some neuronal damage in the dentate gyrus at 5 days post-ADX. CRT did not significantly reduce the neuronal damage at 5 days post-ADX; however, neuronal damage was not shown at 42 post-ADX with CRT. Ki67 (a marker for cell proliferation) and doublecortin (DCX, a marker for neuronal differentiation) immunoreaction was detected in the SZDG. ADX transiently increased cell proliferation and neuroblast differentiation 5 days after ADX, not 42 days, after ADX, and the CRT 42 days after ADX prominently decreased cell proliferation and neuroblast differentiation in the dentate gyrus. These results suggest that adrenal corticosteroid hormone is not essential for cell proliferation and neuroblast differentiation in long-term period after ADX. 相似文献
1000.
Park JH Yoo KY Lee CH Kim IH Shin BN Choi JH Park JH Hwang IK Won MH 《Neurochemical research》2011,36(6):1037-1045
Stress leads to changes in homeostasis and internal balance of the body and is known to be one of important factors in the
development of several diseases. In the present study, we investigated changes in glucocorticoid receptor (GR) and ionized
calcium-binding adapter molecule 1 (Iba-1) immunoreactivity in the adult and aged gerbil hippocampus after chronic restraint
stress. Serum corticosterone level was much higher in both the stress-groups than the control groups. No neuronal death was
found in all hippocampal subregions of the adult and aged gerbil after chronic restraint stress. GR immunoreactivity was decreased
in both the adult and aged groups after repeated restraint stress; however, GR immunoreactivity in the adult-stress-group
was decreased much more than that in the aged-stress-group. Iba-1 immunoreactive microglia were hypertrophied and activated
in the adult group after repeated restraint stress; in the aged-stress-group, there was no any significant change in Iba-1
immunoreactive microglia. In brief, level of GR, not Iba-1, in the hippocampus was much decreased in the adult gerbil compared
to the aged gerbil following chronic restraint stress. 相似文献