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991.
James R. KerfootJr. Jerome J. Lorenz Ralph G. Turingan 《Environmental Biology of Fishes》2011,92(1):125-139
Environmental factors, such as temperature, dissolved oxygen, salinity, and pH may influence the population dynamics of an
introduced species by imposing limits to its distribution and abundance. In 1957, the non-indigenous pike killifish, Belonesox belizanus Kner, was released into a Miami-Dade County, Florida, canal, from which it has since spread across most of south Florida.
The main goal of this study was to characterize patterns of covariation between B. belizanus density and temporal, spatial, and physicochemical variables, and attempt to identify which physicochemical variables may
explain variation in densities of this species. Results of AICc model selection indicated that patterns of physicochemical variables such as pH, salinity, and temperature correlated with
annual change in B. belizanus density, and that these physicochemical-density patterns were mesohabitat specific. For the southern most sites, the interaction
between temperature and salinity provide the best model to explain B. belizanus density, whereas variability in pH provides the best model at northern sites. These patterns of covariance between density
and specific physicochemical variables suggests that specific mesohabitat characteristics may play a role in mediating the
physiological, behavioral, and/or ecological performance of this introduced species in Florida and elsewhere. Future studies
will test hypotheses on the direct and indirect effects of these physicochemical variables within the context of specific
mesohabitats on the behavior and physiology of B. belizanus in its novel environment in South Florida. 相似文献
992.
Sand Forest in the Maputaland region of KwaZulu-Natal in South Africa is deemed the most valuable, but also probably the most
complex vegetation type of this part of the Maputaland–Pondoland–Albany hotspot of biodiversity. However, Sand Forest is under
threat from the current human population growth in that region as well as from uncontrolled increases in wild herbivore numbers
in conservation areas. The present study compares the impacts of herbivores and humans on the state of woody resources between
two sites under differing utilisation regimes. Sand Forest was found to be a complex association of tree assemblages defined
by different canopy and subcanopy properties. Although marked differences in the abundance of selected species were noted
at the two sites, the Sand Forest remained dominated by fine-grained species under both utilisation regimes. The fine-grained
nature of Sand Forest implies that regeneration depends on the creation of small canopy gaps either by natural processes,
humans or elephants, while the creation of large gaps could transform it into woodland. Management of conservation areas where
Sand Forest occurs should therefore concentrate efforts on regulating animal populations to levels that provide gap properties
that favour forest regeneration. 相似文献
993.
Carl W. Decker Jerome Garcia Kristelle Gatchalian Deronisha Arceneaux Clarice Choi Si Cave Derick Han Jeniffer B. Hernandez 《Biochemistry and Biophysics Reports》2020
Mitochondria oscillate along a morphological continuum from fragmented individual units to hyperfused tubular networks. Their position at the junction of catabolic and anabolic metabolism couples this morphological plasticity, called mitochondrial dynamics, to larger cellular metabolic programs, which in turn implicate mitochondria in a number of disease states. In many cancers, fragmented mitochondria engage the cell with the biosynthetic capacity of aerobic glycolysis in service of proliferation and progression. Chemo-resistant cancers, however, favor remodeling dynamics that yield fused mitochondrial assemblies utilizing oxidative phosphorylation (OXPHOS) through the electron transport chain (ETC). In this study, expression of Mitofusin-2 (MFN-2), a GTPase protein mediator of mitochondrial fusion, was found to closely correlate to Jurkat leukemia cell survival post doxorubicin (DxR) assault. Moreover, this was accompanied by dramatically increased expression of OXPHOS respiratory complexes and ATP Synthase, as well as a commensurate escalation of state III respiration and respiratory control ratio (RCR). Importantly, CRISPR knockout of MFN-2 resulted in a considerable decrease of doxorubicin (DxR) median lethal dose compared to a treated wildtype control, suggesting an important role of mitochondrial fusion in chemotherapy sensitivity and acute resistance. 相似文献
994.
995.
Xiangdong Bu Craig H. Warden Yu-Rong Xia Cynthia De Meester Donald L. Puppione Scott Teruya Beth Lokensgard Siamac Daneshmand Jane Brown Richard J. Gray Jerome I. Rotter Aldons J. Lusis 《Human genetics》1994,93(6):639-648
We have tested for evidence of linkage between the genetic loci determining concentrations and composition of plasma high density lipoproteins (HDL) with the genes for the major apolipoproteins and enzymes participating in lipoprotein metabolism. These genes include those encoding various apolipoproteins (apo), including apoA-I, apoA-II, apoA-IV, apoB, apoC-I, apoC-II, apoC-III, apoE, and apo(a), cholesteryl ester transfer protein (CETP), HDL-binding protein, lipoprotein lipase, and the low density lipoprotein (LDL) receptor. Polymorphisms of these genes, and nearby highly polymorphic simple sequence repeat markers, were examined by quantitative sib-pair linkage analysis in 30 coronary artery disease families consisting of a total of 366 individuals. Evidence for linkage was observed between a marker locus D16S313 linked to the CETP locus and a locus determining plasma HDL-cholesterol concentration (P = 0.002), and the genetic locus for apoA-II and a locus determining the levels of the major apolipoproteins of HDL, apoA-I and apoA-II (P = 0.009 and 0.02, respectively). HDL level was also influenced by the variation at the apo(a) locus on chromosome 6 (P = 0.02). Thus, these data indicate the simultaneous involvement of at least two different genetic loci in the determination of the levels of HDL and its associated lipoproteins. 相似文献
996.
Jerome M. Feldman James W. Plonk James C. Cornette 《Prostaglandins & other lipid mediators》1974,7(6):501-506
Using specific radioimmunoassay procedures we measured prostaglandin F2α (PGF2α) and 13, 14-dihydro-15-keto prostaglandin F2α (PGF2α metabolite) in 12 patients with carcinoid tumors. Although PGF2α and PGF2α metabolite were each modestly elevated in 17% of the patients the magnitude of the elevation did not correlate with the symptoms of the carcinoid syndrome. The 24 hour urinary 5-hydroxyindoleacetic acid excretion showed a good correlation with carcinoid symptoms while the serum serotonin concentration showed a fair correlation with carcinoid symptoms. We conclude that serum elevation of PGF2α is not a frequent occurrence in patients with the carcinoid syndrome. 相似文献
997.
Jerome F Sah Richard L Eckert Roshantha A S Chandraratna Ellen A Rorke 《The Journal of biological chemistry》2002,277(12):9728-9735
Human papillomavirus (HPV) is an important etiological agent in the genesis of cervical cancer. HPV-positive cervical tumors and human papillomavirus-positive cell lines display increased epidermal growth factor receptor (EGFR) expression, which is associated with increased cell proliferation. ECE16-1 cells are an HPV-immortalized human ectocervical epithelial cell line that is a model of HPV-associated cervical neoplasia and displays elevated EGFR levels. In the present study, we evaluated the effects of receptor-selective retinoid ligands on EGFR-associated signal transduction. We show that retinoic acid receptor (RAR)-selective ligands reduce EGFR level and the magnitude and duration of EGFR activation in EGF-stimulated cells. These effects are reversed by cotreatment with an RAR antagonist. To identify the mechanism, we examined the effects of retinoid treatments on EGF-dependent signaling. Stimulation with EGF causes a biphasic activation of the ERK1/2 MAPK. The first peak of activation is present at 20 min, and the second is present at 36 h. This activation subsequently leads to an increase in the cyclin D1 level and increased cell proliferation. Simultaneous treatment with EGF and a RAR-selective retinoid inhibits both phases of ERK1/2 activation, completely eliminates the cyclin D1 induction, and suppresses EGF-dependent cell proliferation. This effect is specific as retinoid treatment does not alter the level or activity of other EGFR-regulated kinases, including AKT and the MAPKs p38 and JNK. Retinoid X receptor-selective ligands, in contrast, did not regulate these responses. These results suggest that RAR ligand-associated down-regulation of EGFR activity reduces cell proliferation by reducing the magnitude and duration of EGF-dependent ERK1/2 activation. 相似文献
998.
The transport of L-methionine in human diploid fibroblast strain WI38 was investigated. The uptake of l-methionine was measured in sparse cell cultures in a simple balanced salt solution buffered with either Tris·HCl of N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES). Similar results were obtained with these two buffers. Cultures were allowed to equilibrate with the buffered saline before transport was measured. The presence of glucose in the buffered saline results in a slight reduction in the initial rate of transport for the first 2 h of equilibration in part buffered saline. l-Methionine is actively transported in WI38 by saturable, chemically specific mechanisms which are temperature, pH and, in part, Na+ dependent, and are reactive with both l- and d-stereoisomers. Kinetic analysis of initial rates of transport at substrate concentrations from 0.0005 to 100 mM indicated the presence of two saturable transport systems. System 1 has an apparent KM of 21.7 μM and an apparent V of 3.57 nmol/mg per min. System 2 has an apparent KM of 547 μM and an apparent V of 22.6 nmol/mg per min. Kinetic analysis of initial rates of transport in Na+- free media or after treatment with ouabain suggested that system 1 is Na+ independent and that system 2 is Na+ dependent. Preloading of cells with unlabeled l-methionine greatly increases the initial rate of uptake. Efflux of transported methionine is temperature dependent, and is greatly increased in the presence of unlabeled l- or d-methionine or l-phenylalanine, but not in the presence of l-arginine. l-Methionine transport is strongly inhibited by other neutral amino acids, and is very weakly inhibited by dibasic amino acids, dicarboxylic amino acids, proline or glycine. 相似文献
999.
1000.
Numerical methods are presented for simulating stochastic-in-time current pulses for an electrodiffusion model of the biological channel, with a fixed applied voltage across the channel. The electrodiffusion model consists of the parabolic advection-diffusion equation coupled either to Gauss' law or Poisson's equation, depending on the choice of boundary conditions. The TRBDF2 method is employed for the advection-diffusion equation. The rectangular wave shape of previously simulated traveling wave current pulses is preserved by the full set of partial differential equations for electrodiffusion. 相似文献