Effects of low‐oxygen conditions on embryo growth in the painted turtle,Chrysemys picta          下载免费PDF全文

Gerardo A. CORDERO  Matthew L. KARNATZ  Jon C. SVENDSEN  Eric J. GANGLOFF 《Integrative zoology》2017,12(2):148-156

Low‐oxygen conditions (hypoxia; <21% O₂) are considered unfavorable for growth; yet, embryos of many vertebrate taxa develop successfully in hypoxic subterranean environments. Although enhanced tolerance to hypoxia has been demonstrated in adult reptiles, such as in the painted turtle (Chrysemys picta), its effects on sensitive embryo life stages warrant attention. We tested the hypothesis that short‐term hypoxia negatively affects growth during day 40 of development in C. picta, when O₂ demands are highest in embryos. A brief, but severe, hypoxic event (5% O₂ for 0.5 h) moderately affected embryo growth, causing a 13% reduction in mass (relative to a normoxic control). The same condition had no effect during day 27; instead, a nearly anoxic event (1% O₂ for 72 h) caused a 5% mass reduction. All embryos survived the egg incubation period. Our study supports the assumption that reptilian embryos are resilient to intermittently low O₂ in subterranean nests. Further work is needed to ascertain responses to suboptimal O₂ levels while undergoing dynamic changes in developmental physiology.  相似文献   

Reconstructing 290 years of a data‐poor fishery through ethnographic and archival research: The East Pacific green turtle (Chelonia mydas) in Baja California,Mexico          下载免费PDF全文

Michelle‐María Early‐Capistrán  Andrea Sáenz‐Arroyo  José‐Gilberto Cardoso‐Mohedano  Gerardo Garibay‐Melo  Volker Koch 《Fish and Fisheries》2018,19(1):57-77

Evaluating historical changes in the exploitation of marine organisms is a key challenge in fisheries ecology and marine conservation. In the Eastern Pacific, marine turtles were exploited for millennia before systematic monitoring began <50 years ago. Using ethnographic and historical data, we generated a detailed reconstruction of the East Pacific green sea turtle (Chelonia mydas) fishery in Mexico's Baja California peninsula from 1700 to 1990. Sea turtles from the region's important feeding areas were a staple food source from the earliest phases of human occupation, dating back at least 12,000 years. In contrast with regions such as the Caribbean, small human populations and limited market access resulted in apparently sustainable turtle harvests until the second half of the 20th century. We found that the estimated annual catches between 1960 and 1980 exceeded the estimated annual catches of the previous 250 years by an order of magnitude, leading to the collapse of the fishery and the depletion of the green turtle population. A total ban on sea turtle captures in 1990, comprehensive nesting beach protection, and significant conservation efforts resulted in increases in breeding females on nesting beaches and catch rates in scientific monitoring on main feeding grounds since the early 2000s. This provides a positive outlook for this once‐depleted population segment. Although further research is needed to evaluate current conservation status, we have identified a date, between 1950 and 1960, which can serve as a reliable temporal reference for future evaluations of historical baseline abundance in this region.  相似文献   

n-3 Fatty acids, hypertension and risk of cognitive decline among older adults in the Atherosclerosis Risk in Communities (ARIC) study   总被引：1，自引：0，他引：1  

Beydoun MA  Kaufman JS  Sloane PD  Heiss G  Ibrahim J 《Public health nutrition》2008,11(1):17-29

OBJECTIVE: Recent research indicates that n-3 fatty acids can inhibit cognitive decline, perhaps differentially by hypertensive status. DESIGN: We tested these hypotheses in a prospective cohort study (the Atherosclerosis Risk in Communities). Dietary assessment using a food-frequency questionnaire and plasma fatty acid exposure by gas chromatography were completed in 1987-1989 (visit 1), while cognitive assessment with three screening tools--the Delayed Word Recall Test, the Digit Symbol Substitution Test of the Wechsler Adult Intelligence Scale-Revised and the Word Fluency Test (WFT)--was completed in 1990-1992 (visit 2) and 1996-1998 (visit 4). Regression calibration and simulation extrapolation were used to control for measurement error in dietary exposures. SETTING: Four US communities--Forsyth County (North Carolina), Jackson (Mississippi), suburbs of Minneapolis (Minnesota) and Washington County (Maryland). SUBJECTS: Men and women aged 50-65 years at visit 1 with complete dietary data (n = 7814); white men and women in same age group in the Minnesota field centre with complete plasma fatty acid data (n = 2251). RESULTS: Findings indicated that an increase of one standard deviation in dietary long-chain n-3 fatty acids (% of energy intake) and balancing long-chain n-3/n-6 decreased the risk of 6-year cognitive decline in verbal fluency with an odds ratio (95% confidence interval) of 0.79 (0.66-0.95) and 0.81 (0.68-0.96), respectively, among hypertensives. An interaction with hypertensive status was found for dietary long-chain n-3 fatty acids (g day-1) and WFT decline (likelihood ratio test, P = 0.06). This exposure in plasma cholesteryl esters was also protective against WFT decline, particularly among hypertensives (OR = 0.51, P < 0.05). CONCLUSION: One implication from our study is that diets rich in fatty acids of marine origin should be considered for middle-aged hypertensive subjects. To this end, randomised clinical trials are needed.  相似文献   

Genetic diversity evaluation of a loquat (<Emphasis Type="Italic">Eriobotrya japonica</Emphasis> (Thunb) Lindl) germplasm collection by SSRs and <Emphasis Type="Italic">S</Emphasis>-allele fragments     

Ana Delia Gisbert  Carlos Romero  José Martínez-Calvo  Carmen Leida  Gerardo Llácer  María Luisa Badenes 《Euphytica》2009,168(1):121-134

Loquat (Eriobotrya japonica (Thunb.) Lindl.) is a minor Rosaceae fruit of growing interest as an alternative to the main fruit crops. In this context, the selection of new cultivars to satisfy the market demand will request the suitable characterization of the available germplasm. In this work, genetic relationships among 83 loquat accessions from different countries belonging to the European loquat germplasm collection, held at the Instituto Valenciano de Investigaciones Agrarias (IVIA) in Moncada (Spain) were evaluated using microsatellites and S-allele fragments. A total of nine single sequence repeats (SSRs) from Malus and Eriobotrya genera revealed 53 informative alleles and the S-RNases consensus primers detected 11 self-incompatibility putative alleles. The combined data allow to distinguish unambiguously 80 out of the 83 accessions studied. Unweighted pair-group method (UPGMA) cluster and principal coordinates analysis (PCoA), based on Dice’s genetic distance, generally grouped genotypes according to their geographic origins and pedigrees. Discrepancies and similarities of the results obtained with other variability analysis, based on pomological traits or molecular markers, on the same loquat collection are discussed.  相似文献   

Mutant prevention concentration of ciprofloxacin and enrofloxacin against Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa     

Pasquali F  Manfreda G 《Veterinary microbiology》2007,119(2-4):304-310

The mutant prevention concentration (MPC) is a new concept meant to face the increased prevalence of antibiotic resistance by using antibiotic concentrations able to prevent the selection of single-step resistant mutants. In the present study, the MPCs of ciprofloxacin and enrofloxacin were evaluated against fully susceptible strains of Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa. Additionally, representative single-step mutants arising after exposure to sub-MPC antibiotic concentrations were investigated for molecular basis of their fluoroquinolone resistance phenotypes. MPC value was recorded when more than 10¹⁰ CFU/mL were spread on Muëller Hinton Agar supplemented with different antibiotic concentrations (from 1X to 16X MIC value). MICs of original strains as well as single-step mutants were determined in presence or absence of the Efflux Pump Inhibitor Phe-Arg-β-naphthylamide (PAβN). Moreover point mutations in the QRDR of the gyrA and parC genes were investigated by sequencing. The enrofloxacin MPC values were 4–16-fold higher than ciprofloxacin values. E. coli and S. Typhimurium representative single-step mutants showed reduced susceptibilities associated with point mutations in the QRDR of the gyrA gene or efflux pump system. P. aeruginosa mutants showed resistance phenotypes associated predominantly with efflux pump system activity. According to in vitro MPC data, ciprofloxacin showed a better efficacy than enrofloxacin, in preventing the selection of E. coli, S. Typhimurium and P. aeruginosa single-step mutants. However, in relation to AUC/MPC ratio, the MPC concept can be applied in vivo to ciprofloxacin and enrofloxacin for E. coli and S. Typhimurium but not for P. aeruginosa.  相似文献   

Buying environmental problems: The invasive potential of imported freshwater turtles in Argentina          下载免费PDF全文

Javier Nori  Geiziane Tessarolo  Gentile F. Ficetola  Rafael Loyola  Valeria Di Cola  Gerardo Leynaud 《水产资源保护:海洋与淡水生态系统》2017,27(3):685-691

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Impact of stand density on water status and leaf gas exchange in Quercus ilex     

Gerardo Moreno  Elena Cubera 《Forest Ecology and Management》2008

Tree thinning reduces tree-to-tree competition and likely contributes to the improvement of tree water status and productivity in water-limited systems. In this study, we examined the importance of competition for water among Quercus ilex trees in open woodlands by comparing the water consumption and physiological status of trees located along stand density gradients which ranged from 10% (low density; LD) to 100% (high density; HD) of canopy cover. The study was carried out at two sites which differed in mean annual rainfall (506 and 816 L m⁻²; D_site and W_site, respectively). Predawn and midday leaf water potential (ψ_d and ψ_m, respectively) and CO₂ assimilation rate (A) were measured every two weeks from mid May to mid September, in eight trees located along a stand density gradient at each site. Sap flow and soil moisture were measured only at D_site. Sap flow was continuously recorded by sap flowmeters (constant heating method) installed in 12 trees along two stand density gradients. Soil moisture (?) was measured every 20 cm for the first meter and then every 50 cm up to 250 cm. Measurements were conducted in 18 soil profiles, 6 located in HD and 12 in LD (six beneath and six out the canopy). At W_site, differences among stand densities for ψ and A were very small and emerged only at the end of the dry season. At D_site, ψ (both predawn and midday), A, ?, and sap flow density were significantly higher in LD trees than in HD ones. At D_site, some water remained unused in the soil at the end of the dry season beyond the canopy in the LD areas, and trees did not experienced such an acute water deficit (ψ_d > −1 MPa) as the HD trees did (ψ_d < −3 MPa). Summer tree transpiration at the stand level (E_stand) tended to saturate with the increase of canopy cover. E_stand increases by 32% when canopy cover goes from 50% to 100%. Results confirmed that the increase of tree-to-tree competition with stand density was much more significant at dry sites. In these sites, tree thinning is recommended as a way to maintain tree functioning.  相似文献   

Polyostotic lymphoma with vertebral involvement and spinal extradural compression in a dog     

Lamagna B  Lamagna F  Meomartino L  Paciello O  Fatone G 《Journal of the American Animal Hospital Association》2006,42(1):71-76

A 10-year-old, male, mixed-breed dog that developed cervical pain and neurological deficits was diagnosed with primary lymphoma of the second cervical vertebra. The cervical lesion was not surgically resectable. A dorsal cervical hemilaminectomy was performed to provide temporary decompression. The dog had complete pain relief after surgery but was euthanized 6 weeks later with recurrent clinical signs and evidence of lymphoma in the right femur.  相似文献   

Identification of case clusters and counties with high infective connectivity in the 2001 epidemic of foot-and-mouth disease in Uruguay     

Chowell G  Rivas AL  Smith SD  Hyman JM 《American journal of veterinary research》2006,67(1):102-113

OBJECTIVE: To evaluate the influence of individual spatial units (ie, counties) on the epidemic spread of foot-and-mouth disease (FMD) virus. SAMPLE POPULATION: 163 counties in Uruguay where there was an outbreak of FMD between April 23 and July 11, 2001. PROCEDURE: A geographically referenced database was created, and the distance between counties (13,203 county pairs), road density of counties (163 counties), and time when cases were reported in those counties (11 weeks of the epidemic) were considered to assess global spatial and spatial-temporal autocorrelation, determine the contribution of links connecting pairs of counties with infected animals, and allow us to hypothesize the influence for spread during the epidemic for counties with greater than the mean infective link contributions. RESULTS: Case clusters were indicated by the Moran Iand Mantel tests during the first 6 weeks of the epidemic. Spatial lags between pairs of counties with infected animals revealed case clustering before and after vaccination was implemented. Temporal lags predicted autocorrelation for up to 3 weeks. Link indices identified counties expected to facilitate epidemic spread. If control measures had been implemented in counties with a high index link (identifiable as early as week 1 of the epidemic), they could have prevented (by week 11 of the epidemic) at least 2.5 times as many cases per square kilometer than the same measures implemented in counties with average link indices. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of spatial autocorrelation and infective link indices may identify network conditions that facilitate (or prevent) disease spread.  相似文献   

Add ecology to the pre-medical curriculum     

Beck C  Klemow K  Paulson J  Bernstein A  Lam M  Middendorf G  Reynolds J  Belanger K  Cardelus C  Cid C  Doshi S  Gerardo N  Jablonski L  Kimmel H  Lowman M  Macrae-Crerar A  Pohlad B  de Roode J  Thomas C 《Science (New York, N.Y.)》2012,335(6074):1301

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