As with any other intensively farmed animal species, the Atlantic salmon has been selectively bred and cross-bred to maximize
desirable traits. Selection tends to diminish genetic diversity in target populations, which among other negative effects
is hypothesized to decrease their capacity to confront a broad variety of pathogens. We have analyzed mitochondrial (mtDNA)
as well as major histocompatibility complex (MHC) DNA sequences from individuals collected from a single aquaculture cage
in southern Chile. Interestingly, only two mtDNA haplotypes were obtained; however, several different MH alleles were detected,
with divergence values that were compared with those of natural populations of salmonids. Thus, it seems evolutionary processes
responsible of keeping MH diversity in the wild managed to retain MH variability in farmed Atlantic salmon, maintaining high
immune diversity despite the generally lower levels of observed neutral genetic diversity. 相似文献
In this work, disks containing different amount of the TiO2 precursor impregnated on the raw red clay were produced. The disks were obtained by pressing in metal template and subsequently calcined at 500 °C. The raw clay was used as rigid support to fix the TiO2. The materials were characterized by X-ray diffraction, diffuse reflectance spectroscopy, N2 adsorption-desorption (BET and BJH), scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy. The ability of disks to produce superoxide and hydroxyl radicals after photoexcitation with UV irradiation was monitored by EPR. The catalytic efficiency was evaluated by the Reactive Red 141 dye discoloration under artificial UV light and sunlight. The reaction parameters such as concentration of RR-141 and irradiation source were evaluated. The results showed that the disks were able to decolorize 97.5% under sunlight at 60 min. The disks were also efficient in the discoloration until the tenth cycle, resulting in discoloration values near the initial cycles. Additionally, the dye fragments produced in cleavage of molecule during the reaction were evaluated by LC/MS-MS.
This study presents, for the first time, information on the eggs and early development of Franciscodoras marmoratus, fish of São Francisco river, Brazil. To analyse the egg ultrastructure and morphological events of embryogenesis, a total of 36 F. marmoratus specimens (18 males and 18 females) were captured and subjected to spawning induction. Gametes were collected by manual extrusion, and fertilization was conducted using the dry method. After fertilization, eggs were kept in incubators with water temperature of 24°C. The embryonic development was monitored using a stereomicroscope until hatching. There was a 67% positive response to hypophysation by the females and the fertilization rate was 73.8 ± 6.2%. The oocytes are discoid, yellow, adhesive and covered by a thick jelly coat. Under the electron scanning microscope, the oocytes presented a surface with pore canals and funnel‐shaped micropyle with a smooth vestibule. Recently extruded oocytes had a mean diameter of 1.27 ± 0.4 mm and after hydration was 1.91 ± 0.05 mm. The jelly coat was 0.34 ± 0.03 mm thickness, and the perivitelline space was 0.19 ± 0.04 mm. Eight phases of the embryonic development were identified, and embryogenesis was completed at 47 h after fertilization, at 24°C water temperature. The recently hatched larvae had 2.76 ± 0.57 mm of total length. These results provide useful information for the successful breeding and reproductive strategies of fishes. 相似文献
An outbreak of necrotic enteritis caused by Clostridium perfringens type C was diagnosed in captive collared (Pecari tajacu) and white-lipped (Tayassu pecari) peccaries housed in the Laboratory of Applied Ethology of Universidade Estadual de Santa Cruz located in Ilhéus, State of Bahia, Brazil. Four collared peccaries and three white-lipped peccaries, all juveniles (25-105 days old), were affected. For all affected animals, lethargy and inappetance were followed by sudden death within 24 hours. Histopathology of intestinal wall, culture of C. perfringens type C, and the identification of beta-toxin from intestinal content confirmed the diagnosis. 相似文献
The multi-functionality of agriculture was studied from June to December 2005 in an upland community in Central Luzon, Philippines, by looking across the entire basin of two small water impounding systems or SWIP (Maasin and Buted II). Several sub-studies were undertaken, namely (a) the role of dominant vegetative cover on the rate of surface runoff and erosion; (b) rainfall–runoff analysis in a sub-watershed (i.e., through runoff experimental plot) and within the main watershed (i.e., reservoir inflow analysis); and (c) the environmental functions of agriculture across the entire watershed. The results indicated that about 85% (i.e., throughfall) of rainfall could reach the ground as vegetations intercept the rest. The runoff experimental plot covering a sub-watershed revealed a good correlation between throughfall and runoff. On the other hand, monitoring of reservoir inflows through which surface runoff was measured indicated similar behavior. Integrating the result of runoff experimental plot studies and reservoir inflow analysis resulted to a rainfall–runoff relation which can be applied in the development of rainwater harvesting scheme. The result also showed the dominance of surface runoff as the main component of reservoir inflow, confirming the soil and water conservation, and flood prevention functions of the system. Flood analysis conducted in both SWIP confirmed their flood prevention function by reducing flood peak discharge. The difference between with and without the reservoir was also highlighted in the process. In the paddy field, a 5-cm water depth was consistently maintained, contributing in retaining about 0.543 and 0.272 MCM of rainwater in Maasin and Buted II, respectively. The value of fostering groundwater recharge throughout the entire system was almost equivalent to the value of flood prevention function. Moreover, SWIP also trapped sediments, thereby preventing offsite impact downstream and in surrounding areas.This paper is part of the progress report of the project “Multi-functionality of Agriculture in Selected Sites in the Philippines” presented in the 6th Meeting of the Working Group for the ASEAN-Japan Project on Multi-functionality of Agriculture in ASEAN Countries. 相似文献
Curimatella lepidura and Steindachnerina elegans are small forage fish, constituting an important link in the food chain, serving as food for larger commercial fish. In this study, characteristics of the eggs, of the oocyte's surface ultrastructure and of the embryogenesis are first described for these species. Absolute fecundity was 40864 ± 8769 oocytes for C. lepidura and 22089 ± 8710 oocytes for S. elegans. Oocytes of both species are yellowish, weakly adhesive and with a post‐fertilization diameter of 1019.5 ± 20.6 μm and 978.75 ± 29.16 μm for C. lepidura and S. elegans, respectively. The ultrastructural analysis, using scanning electron microscopy, showed that the oocyte's surface of both species has pore canals over the entire surface and a funnel‐shaped micropyle. At 24°C, the embryonic development of C. lepidura was completed 25 h after fertilization, and blastopore closure occurred in 7 h 30 min. In S. elegans, larvae hatched 20 h after fertilization, and blastopore closure occurred in 7 h 15 min. The fertilization rate was 74.5 ± 7.96 and 71.2 ± 10.8% for C. lepidura and S. elegans, respectively. This study provides important support for clarifying phylogenetic relationships and in ecological and zoological understanding of Neotropical Curimatidae fish. 相似文献
This study investigated for the first time the reproductive biology of Prochilodus lineatus in a system of rivers in southeastern Brasil, relating it to the role of tributary rivers in the reproductive success of this important commercial fish in the Upper Paraná River basin, where a cascade of hydroelectric dams were deployed. Specimens were caught bimonthly in three river sites: (S1) Grande River, downstream from the Porto Colômbia dam; (S2) Pardo River; and (S3) Mogi Guaçu River. Sex steroid plasma levels, fecundity, follicular atresia, oocyte diameter and gonadosomatic index (GSI) were compared among sites. In S1, fish exhibited changes in the reproductive parameters: lower GSI, oocyte diameter and fecundity and higher follicular atresia index, when compared to S2 and S3. Frequency of maturing fish was higher in S3 and spawning was only registered in S3. In sites S2 and S3, plasma concentrations of testosterone and 17β-estradiol in females and testosterone in males showed wide variations following gonadal maturation. Fish from S1 showed few significant variations in sex steroid concentrations throughout the gonadal cycle. These results indicate that P. lineatus does not reproduce in Grande River (S1), but probably uses the Pardo River (S2) as a migratory route towards the Mogi Guaçu River (S3) where they complete gonadal maturation and spawning. Our findings contribute for understanding the reproductive biology of P. lineatus and to highlight the importance of tributaries in impounded rivers as a favourable environment for migration and spawning of fish. 相似文献
An epidemiological study was conducted in a highland rural community in Peru to determine risk factors for canine echinococcosis caused by Echinococcus granulosus. Dogs were diagnosed using a coproantigen enzyme-linked immunosorbent assay (ELISA). Dog owners were interviewed prior to stool collection and asked for attitudes, practices and beliefs likely to be associated with local patterns of E. granulosus transmission. Univariate and multivariate analysis were used to determine odds ratios (OR) and their 95% confidence intervals (CI). The main risk factors found to be significantly associated with canine echinococcosis by univariate analysis were dog age (3-25 months) (OR, 5.14; CI, 1.7-15.7), female sex (OR, 4.3; CI, 1.4-13.3) and having been fed hydatid infected offal (OR, 2.9; 95% CI, 1.0-8.6). There was complete lack of knowledge about echinococcosis transmission. In addition to periodic dog treatment, control programs need to emphasize education of the human population to increase knowledge of parasite transmission and to change human practices associated with high rates of infection. 相似文献
The testicular morphology, spermatogenesis and occurrence of sperm in the ovarian lumen of Trachelyopterus striatulus were studied using anatomical, histological and biometric techniques. A total of 50 catfish (T. striatulus) were captured, measuring 14.9 ± 2.5 cm of standard length, body weight was 81.2 ± 34.5 g and their testes weighed 16.9 ± 6.1 g. The testes of T. striatulus are paired organs, showing two distinct regions: cranial, which shows a compact medial part and with fringes ventrally, and caudal region, which is formed of the seminal vesicle with fringes laterally and two saculiform expansions. The testes presented a length of 35.2 ± 6.9 mm, and the fringes showed a cranial length of 12.1 ± 3.8 mm and caudal length of 6.4 ± 2.6 mm. Histologically, the cranial fringes are spermatogenic and showed cells with significantly different nuclear diameters, ranging from 8.2 ± 1.5 μm (primary spermatogonia) to 1.88 ± 0.3 μm (spermatid). The seminal vesicles and saculiform expansions showed tubules with a simple prismatic secretory epithelium containing spermatozoa and secretion into the lumen. The caudal fringes are exclusively for secretory flow, consisting of tubules with a simple cuboidal epithelium. The common spermatic duct showed a simple cuboidal epithelium and contained spermatozoa with secretion into the lumen. The secretion of the caudal region is acidophilic, with neutral glycoproteins and sialomucin. T. striatulus ovaries showed free spermatozoa or were organized in spermatozeugmata into the ovarian lumen and between the ovuligers lamellae. 相似文献
