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51.
The changes in collagen content and its solubility in sea bream muscle were studied for variable storage times following the death of the fish, and these variables were related to the evolution of physical parameters important for consumer acceptance: firmness and water-holding capacity (WHC). The results show that the collagen content in muscle diminished slightly over storage time and that this variable was directly related to firmness but inversely related to the water-holding capacity. With regard to collagen solubility, a decline was detected in acid-soluble collagen (ASC) in the first few post mortem hours, perhaps related to the end of rigor mortis that occurs at these stages. Pepsin-soluble collagen (PSC) increased, while insoluble collagen (ISC) decreased from 96 h, coinciding with a loss of firmness. This softening can be explained as a result of specific collagenases acting on the insoluble fraction of the collagen.  相似文献   
52.
Silver carp (Hypophthalmichthys molitrix) is not endemic to Cuba, and egg fertilization is totally artificial; males produce spermatozoa only between March and October. Cryopreservation of silver carp spermatozoa would reduce the number of males needed, minimize handling stress through less frequent stripping, and facilitate artificial propagation when eggs are available. The effects on motility and fry production from eggs fertilized with thawed sperm under farm-conditions were examined in this study. Five, seven and ten percent of dimethyl sulfoxide (DMSO), glycerol and methanol were tested as cryoprotectants. DMSO was a more suitable cryoprotectant than methanol or glycerol. The effect of equilibration time on the motility rate at 10% DMSO was evaluated. Hatching rates equal to the control (P>0.01) were obtained under farm conditions with frozen spermatozoa, stored even for a year in liquid nitrogen, with a final DMSO concentration of 10%. Cryopreservation offers a useful routine method for sperm storage and silver carp handling. To our knowledge, this is the first report on the production of fry from post-thaw silver carp spermatozoa under farming conditions.  相似文献   
53.
Fruit quality traits were studied in 12 exotic accessions and their hybrids with a “Piel de Sapo” inodorus melon cultivar. The genetic relationships among these genotypes were assessed with 16 microsatellite markers, which agreed with the classification of Cucumis callosus, C. pubescens and C. trigonus as accessions within C. melo. There were very large differences between all the exotic accessions and “Piel de Sapo” genotype for fruit traits. When the hybrids were analysed, three different situations regarding mid parent heterosis were found, depending on the trait: no heterosis (soluble solid concentration), highly variable, from negative to positive (fruit weight and fruit diameter) and general positive heterosis (ovary shape, fruit length and fruit shape). Best parent heterosis for fruit shape was also common among hybrids. A highly significant correlation (r = 0.81) was detected between fruit shape and fruit length heterosis, suggesting that fruit shape heterosis is caused mainly by the enlargement of the fruit longitudinally. A highly significant correlation (r = 0.84) between heterosis for fruit shape and genetic distance, as estimated with microsatellites, was also found. These results, together with the previously reported observation that melon fruit shape is polygenic and highly heritable, makes the genetics of melon fruit shape a suitable system for dissecting the genetic and molecular basis of heterosis.  相似文献   
54.
While the modernization of irrigation techniques in recent years has improved water use efficiency, the substitution of open channels by pressurized pipes led to a substantial increase in the energy used in irrigated agriculture. Given the concern for energy savings and sustainability, official administrations have promoted several initiatives to improve energy efficiency in irrigated agriculture, and researchers have developed different tools for the same. Although energy audits have been conducted in irrigation networks managed by Water Users’ Associations, the implementation of energy conservation measures proposed in these audits has not been always successful. This paper, which reviews the energy aspects of irrigation systems modernized in recent decades in Spain and in other countries, considers the characteristics and special features of Water Users’ Associations and proposes an energy management system (EMS) for the same. The stages of the EMS are described, beginning with the definition of energy policy and the establishment, implementation and verification of energy plans, the essential conditions to guarantee the success of the EMS are described, in which energy audits are just a part of a process of continual improvement of energy efficiency. A Strategy for Efficient Energy Management has been implemented in a Water Users’ Association in southeast Spain. The improvement measures proposed in the first energy plan were implemented, and an increase from 60 to 65 % in average energy efficiency was achieved.  相似文献   
55.
The evergreen holm oaks (Quercus ilex subsp. ilex and Q. ilex subsp. ballota) are the most representative tree species in the Iberian peninsula and the main tree species in oak‐rangeland ecosystems (dehesas). Oak decline in western, central and southern parts of Spain has been associated with root rot caused by Phytophthora cinnamomi for decades. However, Phytophthora species such as P.  quercina and P. psychrophila have recently been found associated with Quercus decline in eastern Spain where calcareous soils are predominant. Soil and root samples from two Quercus forests presenting decline symptoms in two different geographical areas in eastern Spain (Carrascar de la Font Roja and Vallivana) were analysed by amplicon pyrosequencing. Metabarcoding analysis showed Phytophthora species diversity, and revealed that an uncultured Phytophthora taxon, named provisionally Phytophthora taxon ballota, was the predominant species in both areas. In addition, a real‐time PCR assay, based on the pyrosequencing results, was developed for the detection of this uncultured Phytophthora taxon, and also for the detection of P. quercina. TaqMan assays were tested on soil and root samples, and on Phytophthora pure cultures. The new assays showed high specificity and were consistent with metabarcoding results. A new real‐time PCR protocol is proposed to evaluate the implication of different Phytophthora spp. in oak decline in eastern Spain.  相似文献   
56.
Frozen-thawed (FT) boar sperm have a reduced fertile life, due in part to a capacitation-like status induced by cooling. Reversal of this cryocapacitation in vitro by exposure to boar seminal plasma (SP) has been demonstrated. The objective of these studies was to determine the effect of SP on the ability of FT sperm to create an oviductal sperm reservoir following artificial insemination (AI). In Experiment one, 35 pre-pubertal gilts were injected (IM) with 400 IU eCG plus 200 IU hCG to induce oestrus. At detection of oestrus, gilts were inseminated with 3 x 10(9) live sperm, either fresh (FS; n = 13), FT (n = 10), or FT supplemented with 10% v/v SP (n = 12). Gilts were killed 8 h later, their reproductive tracts recovered and the uterotubal junctions (UTJs) flushed to recover sperm. Fewer (p < 0.01) sperm were recovered following FT, compared to FS, inseminations, and there was no evident effect of SP. In Experiment two, 30 pre-pubertal gilts received IM injections of 1000 IU eCG followed by 5 mg pLH 80 h later to control time of ovulation. Gilts were inseminated with 3 x 10(9) live FS sperm (n = 6), FT sperm (n = 15) or FT sperm plus 10% SP (n = 9) at 12 h before ovulation and then sacrificed 8 h later. The UTJs were dissected and flushed for sperm recovery. Fewest (p < 0.001) sperm were recovered following FT insemination and there was no evident effect of SP. These data demonstrate that the size of the sperm reservoir is markedly reduced in gilts inseminated with FT sperm. However, the lack of effect of SP suggested that either it did not reverse cryocapacitation or that such a reversal does not impact the in vivo ability to create a sperm reservoir.  相似文献   
57.
ABSTRACT In the pepper Capsicum annuum CM334, which is used by breeders as a source of resistance to Phytophthora spp. and potyviruses, a resistance gene entirely suppresses reproduction of the root-knot nematode (Meloidogyne spp.). The current study compared the histological responses of this resistant line and a susceptible cultivar to infection with the three most damaging root-knot nematodes: M. arenaria, M. incognita, or M. javanica. Resistance of CM334 to root-knot nematodes was associated with unidentified factors that limited nematode penetration and with post-penetration biochemical responses, including the hypersensitive response, which apparently blocked nematode migration and thereby prevented juvenile development and reproduction. High-performance liquid chromatography analysis suggested that phenolic compounds, especially chlorogenic acid, may be involved in CM334 resistance. The response to infection in the resistant line varied with root-knot nematode species and was correlated with nematode behavior and pathogenicity in the susceptible cultivar: nematode species that quickly reached the vascular cylinder and initiated feeding sites in the susceptible cultivar were quickly recognized in CM334 and stopped in the epidermis or cortex. After comparing our data with those from other resistant pepper lines, we suggest that timing of the resistance response and the mechanism of resistance vary with plant genotype, resistance gene, and root-knot nematode species.  相似文献   
58.
The pinewood nematode Bursaphelenchus xylophilus is a severe pest of coniferous trees, and has been designated as a quarantine organism in the European Union. From the sequence of a satellite DNA family characterized in the genome of this nematode, we developed a PCR procedure that allowed the specific discrimination of this species from closely related Bursaphelenchus species found on coniferous trees. Moreover, because of the repetitive nature of satellite DNA, positive amplification was achieved from B. xylophilus single individuals, which should contribute to an easy diagnostic procedure for assisting in the management of this major pest of conifer forests.  相似文献   
59.
60.
P. Abad  C. Jord 《EPPO Bulletin》2000,30(2):281-287
A disease caused by potato Y potyvirus (PVY) affects tomato plantations with variable severity in Tenerife Island. Affected plants show diverse symptoms such as necrotic lesions or mild to severe mosaic in leaves and whitish spots in green fruits that remain after ripening. Tomato PVY isolates and few potato and capsicum PVY isolates have been characterized on the basis of biological, serological and molecular criteria. All PVY isolates reacted positively to monoclonal antibodies specific for PVYO/C or PVYN strains, and nearly 50% of tomato PVY isolates were recognized by both. Differentiation of PVY strains according to the response of inoculated experimental plants was confusing due to the variability of viral aggressiveness and symptomatology induced. RFLP analysis of the CP gene and 3’untranslated region (UTR) revealed high variability. In addition to mixed infection by different PVY strains, the biological and molecular properties of those tomato PVY isolates that react to both monoclonal antibodies could be explained as the result of RNA recombination between distinct PVY strains which infect the same host plant.  相似文献   
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