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1.
Although microorganisms largely drive many ecosystem processes, the relationship between microbial composition and their functioning remains unclear. To tease apart the effects of composition and the environment directly, microbial composition must be manipulated and maintained, ideally in a natural ecosystem. In this study, we aimed to test whether variability in microbial composition affects functional processes in a field setting, by reciprocally transplanting riverbed sediments between low- and high-salinity locations along the Nonesuch River (Maine, USA). We placed the sediments into microbial ‘cages'' to prevent the migration of microorganisms, while allowing the sediments to experience the abiotic conditions of the surroundings. We performed two experiments, short- (1 week) and long-term (7 weeks) reciprocal transplants, after which we assayed a variety of functional processes in the cages. In both experiments, we examined the composition of bacteria generally (targeting the 16S rDNA gene) and sulfate-reducing bacteria (SRB) specifically (targeting the dsrAB gene) using terminal restriction fragment length polymorphism (T-RFLP). In the short-term experiment, sediment processes (CO2 production, CH4 flux, nitrification and enzyme activities) depended on both the sediment''s origin (reflecting differences in microbial composition between salt and freshwater sediments) and the surrounding environment. In the long-term experiment, general bacterial composition (but not SRB composition) shifted in response to their new environment, and this composition was significantly correlated with sediment functioning. Further, sediment origin had a diminished effect, relative to the short-term experiment, on sediment processes. Overall, this study provides direct evidence that microbial composition directly affects functional processes in these sediments. 相似文献
2.
Chromobacterium violaceum is a Gram-negative opportunistic human pathogen and an inhabitant of tropical soils and waterways. Although known primarily for the synthesis of the pigment violacein, and more recently as a reporter strain for quorum sensing, clinical reports of chromobacteriosis comprise the largest block of published literature on this organism. Genome sequencing has revealed many potential virulence factors in this microorganism, and this paper establishes the presence in C. violaceum of a Serratia type-hemolysin (ChlA) and transporter (ChlB). We also show that the hemolysin operon includes a third gene (chlC) that is predicted to encode a phosphorylation domain similar to the receiver domain of response regulators in bacterial signal transduction systems. 相似文献
3.
Bruce J. Ellis Aurelio José Figueredo Barbara H. Brumbach Gabriel L. Schlomer 《Human nature (Hawthorne, N.Y.)》2009,20(2):204-268
The current paper synthesizes theory and data from the field of life history (LH) evolution to advance a new developmental
theory of variation in human LH strategies. The theory posits that clusters of correlated LH traits (e.g., timing of puberty,
age at sexual debut and first birth, parental investment strategies) lie on a slow-to-fast continuum; that harshness (externally
caused levels of morbidity-mortality) and unpredictability (spatial-temporal variation in harshness) are the most fundamental
environmental influences on the evolution and development of LH strategies; and that these influences depend on population
densities and related levels of intraspecific competition and resource scarcity, on age schedules of mortality, on the sensitivity
of morbidity-mortality to the organism’s resource-allocation decisions, and on the extent to which environmental fluctuations
affect individuals versus populations over short versus long timescales. These interrelated factors operate at evolutionary
and developmental levels and should be distinguished because they exert distinctive effects on LH traits and are hierarchically
operative in terms of primacy of influence. Although converging lines of evidence support core assumptions of the theory,
many questions remain unanswered. This review demonstrates the value of applying a multilevel evolutionary-developmental approach
to the analysis of a central feature of human phenotypic variation: LH strategy. 相似文献
4.
Marieke?Pingen Ramin?Sarrami-Forooshani Annemarie?MJ?Wensing Petra?van Ham Agata?Drewniak Charles?AB?Boucher Teunis?BH?GeijtenbeekEmail author Monique?NijhuisEmail author 《Retrovirology》2014,11(1):113
Background
Different patterns of drug resistance are observed in treated and therapy naïve HIV-1 infected populations. Especially the NRTI-related M184I/V variants, which are among the most frequently encountered mutations in treated patients, are underrepresented in the antiretroviral naïve population. M184I/V mutations are known to have a profound effect on viral replication and tend to revert over time in the new host. However it is debated whether a diminished transmission efficacy of HIV variants with a reduced replication capacity can also contribute to the observed discrepancy in genotypic patterns.As dendritic cells (DCs) play a pivotal role in HIV-1 transmission, we used a model containing primary human Langerhans cells (LCs) and DCs to compare the transmission efficacy M184 variants (HIV-M184V/I/T) to HIV wild type (HIV-WT). As control, we used HIV harboring the NNRTI mutation K103N (HIV-K103N) which has a minor effect on replication and is found at a similar prevalence in treated and untreated individuals.Results
In comparison to HIV-WT, the HIV-M184 variants were less efficiently transmitted to CCR5+ Jurkat T cells by both LCs and DCs. The transmission rate of HIV-K103N was slightly reduced to HIV-WT in LCs and even higher than HIV-WT in DCs. Replication experiments in CCR5+ Jurkat T cells revealed no apparent differences in replication capacity between the mutant viruses and HIV-WT. However, viral replication in LCs and DCs was in concordance with the transmission results; replication by the HIV-M184 variants was lower than replication by HIV-WT, and the level of replication of HIV-K103N was intermediate for LCs and higher than HIV-WT for DCs.Conclusions
Our data demonstrate that drug resistant M184-variants display a reduced replication capacity in LCs and DCs which directly impairs their transmission efficacy. As such, diminished transmission efficacy may contribute to the lower prevalence of drug resistant variants in therapy naive individuals.5.
GA McFeters FP Yu BH Pyle PS Stewart 《Journal of industrial microbiology & biotechnology》1995,15(4):333-338
This report reviews the development of a rapidin situ approach to study the physiological responses of bacteria within biofilms to disinfectants. One method utilized direct viable counts (DVC) to assess the disinfection efficacy when thin biofilms were exposed to chlorine or monochloramine. Results obtained using the DVC method were one log higher than plate count (PC) estimates of the surviving population after disinfection. Other methods incorporated the use of fluorogenic stains, a cryotomy technique to yield thin (5-m) sections of biofilm communities and examination by fluorescence microscopy. The fluorogenic stains used in this approach included 5-cyano-2,3-ditolyl tetrazolium chloride (CTC), which indicates cellular electron transport activity and Rhodamine 123, which responds specifically to proton motive force. The use of these stains allowed the microscopic discrimination of physiologically active bacteria as well as heterogeneities of active cells within thicker biofilms. The results of experiments using these techniques with pure culture and binary population biofilms on stainless steel coupons indicated biocidal activity of chlorine-based disinfectants occurred initially at the bulk-fluid interface of the communities and progressed toward the substratum. This approach provided a unique opportunity to describe the spatial response of bacteria within biofilms to antimicrobial agents and address mechanisms explaining their comparative resistance to disinfection in a way that has not been possible using traditional approaches. Results obtained using this alternative approach were also consistently higher than PC data following disinfection. These observations suggest that traditional methods involving biofilm removal and bacterial enumeration by colony formation overestimate biocide efficacy. Hence the alternative approach described here more accurately indicates the ability of bacteria surviving disinfection to recover and grow as well as demonstrate spatial heterogeneities in cellular physiological activities within biofilms. 相似文献
6.
Amit Kumar Tripathi Ashish Dwivedi Manish Kumar Pal Namrata Rastogi Priyanka Gupta Shakir Ali Manjunatha Prabhu BH Hari Narayan Kushwaha Ratan Singh Ray Shio Kumar Singh Shivali Duggal Bhaskar Narayan Durga Prasad Mishra 《Journal of biomedical science》2014,21(1):39
Background
Riboflavin (RF) or vitamin B2 is known to have neuroprotective effects. In the present study, we report the attenuation of the neuroprotective effects of RF under UV-B irradiation. Preconditioning of UV-B irradiated riboflavin (UV-B-RF) showed attenuated neuroprotective effects compared to that of RF in SH-SY5Y neuroblostoma cell line and primary cortical neurons in vitro and a rat model of cerebral ischemia in vivo.Results
Results indicated that RF pretreatment significantly inhibited cell death and reduced LDH secretion compared to that of the UV-B-RF pretreatment in primary cortical neuron cultures subjected to oxygen glucose deprivation in vitro and cortical brain tissue subjected to ischemic injury in vivo. Further mechanistic studies using cortical neuron cultures revealed that RF treatment induced increased miR-203 expression which in turn inhibited c-Jun expression and increased neuronal cell survival. Functional assays clearly demonstrated that the UV-B-RF preconditioning failed to sustain the increased expression of miR-203 and the decreased levels of c-Jun, mediating the neuroprotective effects of RF. UV-B irradiation attenuated the neuroprotective effects of RF through modulation of the miR-203/c-Jun signaling pathway.Conclusion
Thus, the ability of UV-B to serve as a modulator of this neuroprotective signaling pathway warrants further studies into its role as a regulator of other cytoprotective/neuroprotective signaling pathways. 相似文献7.
Y Deng J Zhao D Sakurai KM Kaufman JC Edberg RP Kimberly DL Kamen GS Gilkeson CO Jacob RH Scofield CD Langefeld JA Kelly ME Alarcón-Riquelme BIOLUPUS GENLES Networks JB Harley TJ Vyse BI Freedman PM Gaffney KM Sivils JA James TB Niewold RM Cantor W Chen BH Hahn EE Brown PROFILE BP Tsao 《Arthritis research & therapy》2012,14(Z3):A5
8.
F Özdal-Kurt I Tuğlu HS Vatansever S Tong BH Şen SI Deliloğlu-Gürhan 《Biotechnic & histochemistry》2016,91(6):412-422
We investigated the effects of different implant biomaterials on cultured canine bone marrow stromal cells (BMSC) undergoing differentiation into osteoblasts (dBMSC). BMSC were isolated from canine humerus by marrow aspiration, cultured and differentiated on calcium phosphate scaffold (CPS), hydroxyapatite, hydroxyapatite in gel form and titanium mesh. We used the MTT method to determine the effects of osteogenic media on proliferation. The characteristics of dBMSC were assessed using alizarin red (AR), immunocytochemistry and osteoblastic markers including alkaline phosphatase/von Kossa (ALP/VK), osteocalcin (OC) and osteonectin (ON), and ELISA. The morphology of dBMSC on the biomaterials was investigated using inverted phase contrast microscopy and scanning electron microscopy. We detected expression of ALP/VK, AR, OC and ON by day 7 of culture; expression increased from day 14 until day 21. CPS supported the best adhesion, cell spreading, proliferation and differentiation of BMSCs. The effects of the biomaterials depended on their surface properties. Expression of osteoblastic markers showed that canine dBMSCs became functional osteoblasts. Tissue engineered stem cells can be useful clinically for autologous implants for treating bone wounds. 相似文献
9.
This article is broadly concerned with the spatial or locational principles governing hunter-gatherer society. Toward this end, the settlement-community hierarchy of the southern Chipewyan Indians is interpreted as a framework for resolving the conflicting advantages and disadvantages of nucleation and dispersion, for regulating information flow, and for maintaining organizational flexibility and options in decision making. Recent ethnoarcheological research reveals a socio-spatial organization based on three recurring stages or phases: (1) concentrated summer band, (2) winter staging community, and (3) dispersed winter hunting encampment. Parallels with other Northeastern Athapaskan groups are noted, and the issue of cultural syncretism in socio-spatial forms is raised. 相似文献
10.
Barbara Hagenah Brumbach Aurelio José Figueredo Bruce J. Ellis 《Human nature (Hawthorne, N.Y.)》2009,20(1):25-51
The National Longitudinal Study of Adolescent Health data were used to test predictions from life history theory. We hypothesized
that (1) in young adulthood an emerging life history strategy would exist as a common factor underlying many life history
traits (e.g., health, relationship stability, economic success), (2) both environmental harshness and unpredictability would
account for unique variance in expression of adolescent and young adult life history strategies, and (3) adolescent life history
traits would predict young adult life history strategy. These predictions were supported. The current findings suggest that
the environmental parameters of harshness and unpredictability have concurrent effects on life history development in adolescence,
as well as longitudinal effects into young adulthood. In addition, life history traits appear to be stable across developmental
time from adolescence into young adulthood.
Barbara Hagenah Brumbach is an assistant professor in the Department of Psychology at Northern Arizona University. Her research examines individual differences in life history strategy and ecological predictors of the development of life history strategy over the life course. Aurelio José Figueredo is a professor of psychology at the University of Arizona and serves as director of the Graduate Program in Ethology and Evolutionary Psychology. His major area of research interest is the evolutionary psychology and behavioral development of life history strategy, sex, and violence in human and nonhuman animals, and the quantitative ethology and social development of insects, birds, and primates. Bruce J. Ellis is a professor in the Division of Family Studies and Human Development and the John & Doris Norton Endowed Chair in Fathers, Parenting, and Families at the University of Arizona. He seeks to integrate evolutionary and developmental perspectives in his research on family environments, child stress reactivity, and sexual development. 相似文献
Barbara Hagenah BrumbachEmail: |
Barbara Hagenah Brumbach is an assistant professor in the Department of Psychology at Northern Arizona University. Her research examines individual differences in life history strategy and ecological predictors of the development of life history strategy over the life course. Aurelio José Figueredo is a professor of psychology at the University of Arizona and serves as director of the Graduate Program in Ethology and Evolutionary Psychology. His major area of research interest is the evolutionary psychology and behavioral development of life history strategy, sex, and violence in human and nonhuman animals, and the quantitative ethology and social development of insects, birds, and primates. Bruce J. Ellis is a professor in the Division of Family Studies and Human Development and the John & Doris Norton Endowed Chair in Fathers, Parenting, and Families at the University of Arizona. He seeks to integrate evolutionary and developmental perspectives in his research on family environments, child stress reactivity, and sexual development. 相似文献