First report of Enterocytozoon bieneusi from dairy cattle in Argentina     

Valeria F. Del Coco  María Alejandra Córdoba  Gladys Bilbao  Pinto de Almeida Castro  Juan Angel Basualdo  Mónica Santín 《Veterinary parasitology》2014,199(1-2):112-115

Fecal specimens were obtained from a total of 70 dairy calves less than two months old on 11 municipalities in Buenos Aires, Argentina. After removal of fecal debris by sieving and sucrose flotation, specimens were subjected to PCR to detect the presence of Enterocytozoon bieneusi. PCR revealed a 14.3% of prevalence for E. bieneusi with 10 positive calves from 7 municipalities. Gene sequence analysis conducted in all samples positives by PCR revealed the presence of six genotypes; four previously reported in cattle as well as humans (D, I, J, and BEB4), one never reported in cattle before but previously reported in humans (EbpC), and one novel genotype (BEB10). These results constitute the first molecular characterization of E. bieneusi in Argentina, and suggest a potential risk of zoonotic transmission in this area.  相似文献   

Intestinal phytase I: Detection and preliminary characterization of activity in the intestinal brush border membrane of hybrid striped bass Morone saxatilis × M. chrysops     

L.E. Ellestad  R. Angel  J.H. Soares Jr. 《Fish physiology and biochemistry》2002,26(3):249-258

While numerous studies have evaluated intestinal phytase activity in terrestrial monogastric species, little work has been conducted investigating the enzyme's activity in finfish. This experiment was conducted to determine if hybrid striped bass Morone saxatilis × M. chrysops possess intestinal phytase activity, and to perform a preliminary characterization of this activity in terms of pH, metal ion dependence and substrate kinetics. Hybrid bass do exhibit low levels of intestinal phytase activity. The activity has an acidic pH optimum between 3.5 and 4.5. Low concentrations of Mn²⁺ slightly enhance this activity. The divalent cations Mg²⁺ and Zn²⁺ were shown to either have no effect on the enzyme activity or to be inhibitory, particularly at high concentrations. The present results indicate that intestinal phytase activity in hybrid bass does follow Michaelis-Menten kinetics, with estimated K_m and V_max values of 2.5 mM phytate and 4.8 units mg⁻¹ protein, respectively. The physiologic significance of the enzyme's presence in hybrid striped bass is questionable due to the low activity as compared to terrestrial monogastrics, the acidic pH optimum and the low affinity the enzyme appears to have for phytate. These observations also raise the question of whether the intestinal phytase activity detected in hybrid bass is merely a manifestation of non-specific acid phosphatase activity. Further investigation is needed to determine the practical significance of phytase activity in hybrid bass in terms of phytate phosphorus utilization. Additional experiments should also be conducted which evaluate intestinal phytase activity in other important aquacultured finfish species. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Estudio Radiológico del Esternón del Ovino en Crecimiento     

M. T. Guillen    A. Robina  S. Regodon 《Anatomia, histologia, embryologia》1993,22(1):91-99

Radiological investigation of the sternum of the sheep A radiological investigation of the sternum of the sheep demonstrated distinct growth phases. Forty Merino sheep of mixed breeds were distributed into 4 age groups of 0, 45, 105 and 270 days. Each animal was radiographed in sternal and lateral recumbency. Measurements were made from the radiographs. The sternebra are rectangular in newborn and become concave in adult. The curvature of the sternum is 16 to 17° at day 0 and 27–28° at day 270. The nucleus of ossification was seen in all sternebrae at 45 days of age, they were present only in the most caudal sternebrae at 105 days.  相似文献   

Factors controlling suspended sediment yield during runoff events in small headwater catchments of the Basque Country   总被引：1，自引：0，他引：1  

Ane Zabaleta  Miren MartínezJesus Angel Uriarte  Iñaki Antigüedad 《CATENA》2007

For the first time in the Basque Country, turbidity (NTU), discharge (l/s) and precipitation (mm) have been continuously monitored in the gauging stations located at the outlet of three catchments (Aixola, Barrendiola and Añarbe) since October 2003. In this study, several data sets derived from flood events were used to develop turbidity and suspended sediment relationships for the three catchments separately, and so to estimate continuous suspended sediment concentration (SSC). Linear relationships are found in Barrendiola and Añarbe, and two curvilinear relationships for Aixola owing to changing sediment sources in the catchment. Several event (discharge, precipitation and suspended sediment concentration) and pre-event (discharge and precipitation) factors are calculated for all the events registered. With them correlation matrixes were developed for each catchment. Although some differences are found between catchments good correlation between precipitation (P), discharge (Q) and suspended sediment (SS) variables is found in general. Pre-event conditions are also well correlated with Q and SS variables in Barrendiola (higher regulation capacity) and Añarbe (larger area) but not in Aixola (“flash floods”). SSC-discharge evolutions through the events were also analysed. For Aixola four different types of hysteretic loops were observed: single lined, clockwise, counter-clockwise and eight-shaped; while for Barrendiola and Añarbe just clockwise loops were observed.  相似文献   

Nutrient Loading by Precipitation in the Maracaibo Lake Basin, Venezuela     

Jose A Morales  Ligbel Sanchez  Harvi Velasquez  Beatriz De Borrego  Marlene De Nava  Denis Portillo  Yulixis Cano  Angel Morillo  Ana Albornoz  Elsa Socorro 《Water, air, and soil pollution》2001,130(1-4):511-516

Nutrient content and pH of rain samples collected at nine sites during 1988-1996 were studied to determine the amounts of N, P and S added by precipitation over Maracaibo Lake basin. The basin is a wide depression occupied by Lake Maracaibo and extensive alluvial plains and delimited by a mountainous zone of variable physiolgraphic characteristics with different cattle ranching and industrial activities. Rain pHs averaged ≈ 4 to 6, individual samples occasionally reached as low as pH 3 in the south basin. NH₄ ⁺ levels were significantly higher (up to 2.6 mg/l NH₄-N) than NO₃ ^? plus NO₂ ^?. Phosphorus levels were low, ranging from undetectable to 1.5 mg/l. The amounts of inorganic N/ha/yr added ranged from ≈ 5.4 Kg in the north to ≈ 8 Kg in the south basin; around the lakeshore, it was estimated that ≈ 9.8–16.8 Kg TN/ha (≈ 55 % as organic-N) are annually deposited. The annual amounts of SO₄-S/ha added range from ≈ 10 to 13 Kg. The contribution of precipitation to P in the ecosystem is very small; ≈ 0.02 – 0.8 Kg of PO₄-P/ha/yr was added in basin. The results of this study show that precipitation represents a significant factor for the total nitrogen and sulfur loading to Maracaibo Lake Basin.  相似文献   

Wind as a long-distance dispersal vehicle in the Southern Hemisphere     

Muñoz J  Felicísimo AM  Cabezas F  Burgaz AR  Martínez I 《Science (New York, N.Y.)》2004,304(5674):1144-1147

Anisotropic (direction-dependent) long-distance dispersal (LDD) by wind has been invoked to explain the strong floristic affinities shared among landmasses in the Southern Hemisphere. Its contribution has not yet been systematically tested because of the previous lack of global data on winds. We used global winds coverage from the National Aeronautics and Space Administration SeaWinds scatterometer to test whether floristic similarities of Southern Hemisphere moss, liverwort, lichen, and pteridophyte floras conform better with (i) the anisotropic LDD hypothesis, which predicts that connection by "wind highways" increases floristic similarities, or (ii) a direction-independent LDD hypothesis, which predicts that floristic similarities among sites increase with geographic proximity. We found a stronger correlation of floristic similarities with wind connectivity than with geographic proximities, which supports the idea that wind is a dispersal vehicle for many organisms in the Southern Hemisphere.  相似文献   

Developmentally regulated activation of a SINE B2 repeat as a domain boundary in organogenesis   总被引：1，自引：0，他引：1  

Lunyak VV  Prefontaine GG  Núñez E  Cramer T  Ju BG  Ohgi KA  Hutt K  Roy R  García-Díaz A  Zhu X  Yung Y  Montoliu L  Glass CK  Rosenfeld MG 《Science (New York, N.Y.)》2007,317(5835):248-251

  相似文献   

Biological consequences of the 1975 el nino     

Cowles TJ  Barber RT  Guillen O 《Science (New York, N.Y.)》1977,195(4275):285-287

The weak El Ni?o event of 1975 had a clearly defined effect on the biological productivity of the southeastern tropical Pacific. During February and March 1975, warm (27 degrees C) water of low salinity (33.5 parts per thousand) and low nutrient content extended south across the equator east of the Galápagos Islands, replacing the nutrient-rich water normally supplied by equatorial upwelling. Equatorial primary production was less than 0.2 gram of carbon per square meter per day, one-fifth of the normal value. At the maximum development of the 1975 event, the coastal region of Peru continued to have strong nearshore upwelling with primary production values greater than 2.5 grams of carbon per square meter per day, although the zone of high production was confined to a 250-kilometer-wide band, one-half its normal width. The biological effects of the 1975 event were short-lived; in April and May 1975 the equatorial region had begun to reestablish its normal levels of primary production.  相似文献   

Activity of octylthiotrifluoropropan-2-one,a potent esterase inhibitor,on growth,development, and intraspecific communication in Spodoptera littoralis and Sesamia nonagrioides     

Reddy GV  Quero C  Guerrero A 《Journal of agricultural and food chemistry》2002,50(24):7062-7068

A series of experiments were conducted to examine the effect of 3-octylthio-1,1,1-trifluoro-2-propanone (OTFP) on growth, development, and behavior of the cotton leafworm, Spodoptera littoralis (Lepidoptera: Noctuidae), and the corn stalk borer, Sesamia nonagrioides (Lepidoptera: Noctuidae). The chemical behaved as an oviposition deterrent and, when added to the diet of the second-instar larvae of both insects, reduced diet consumption and growth, pupation, and adult emergence. Treatment of 100-5000 ng of the compound on fourth-instar larvae for 3-24 h, however, did not produce significant differences in the amount of diet ingested. Our results suggest that the effect of OTFP is long-lasting and that the inhibitor is not fully detoxified by the detoxification enzymes of the digestive tract of the insects. In behavioral assays, adult males which had been treated with the chemical at the larval stage were less attracted to the pheromone source than regular untreated males. When Sp. littoralis untreated females were used as the attractant source, treated males also displayed significantly fewer contacts with the cage-containing females than untreated or solvent-treated males. In the presence of treated females, only 27% of treated males successfully completed the flight in comparison to animals responding to solvent-treated females (54.5%). By contrast, when Se. nonagrioides females, whether they had been subjected or not to the treatment, were used as the attractant source, males were similarly attracted to them regardless of whether they had been treated or not at the larval stage. Analyses of gland extracts of Sp. littoralis treated females showed no difference from control insects in the qualitative or quantitative composition of the pheromone blend. The results obtained, in combination with other results previously reported by us (Riba, M.; Sans, A.; Bau, P.; Grolleau, G.; Renou, M.; Guerrero, A. J. Chem. Ecol. 2001, 27, 1879-1897), provide new and relevant information about the possible utility of these chemicals in future studies directed to the development of new approaches for pest control.  相似文献   

Lead dietary intake in a Spanish population (Canary Islands)   总被引：2，自引：0，他引：2  

Rubio C  González-Iglesias T  Revert C  Reguera JI  Gutiérrez AJ  Hardisson A 《Journal of agricultural and food chemistry》2005,53(16):6543-6549

For most people diet is the main route of exposure to trace metals, so information about dietary intake is also important to assess risks to human health for these elements. The purpose of this study was to determine the levels of Pb in the foods and drinks of highest consumption in the authors' our community to estimate daily intakes of Pb for each of the seven Canary Islands. Four hundred and twenty samples were analyzed using GFAAS. The total Pb intake of the Canarian population is 72.8 microg/day, 29.12% (for a person of 70 kg body weight) of the provisional tolerable weekly intake limit of 25 microg/kg fixed by the FAO/WHO. The island that presents the highest lead intake is La Gomera, followed by Lanzarote, Tenerife, and Gran Canaria islands. These four islands present a lead dietary intake over the mean Pb intake for the whole archipelago. The islands with lower Pb intakes are La Palma and Fuerteventura, with intakes under 70 microg/day. These results have also been compared with the values found for other national and international communities.  相似文献