Capacitation is a biological phenomenon occurring prior to fertilization and is a multiple event process. Many physiological and biochemical changes takes place during the process; these changes are related to lipid composition of membrane, intracellular modulation of ion concentration, protein phosphorylation, sperm movement and membrane permeability. These events occur when the sperm is exposed to the new environment of ion concentration in the female reproductive tract. Ions such as bicarbonate and calcium facilitate capacitation by activating adenylyl cyclase, thus initiating protein kinase A (PKA) signalling cascade. Extracellular‐regulated kinase pathway is activated by ligand binding to the membrane receptors and intracellular activation by reactive oxygen species (ROS). Activation of these pathways leads to the phosphorylation of different proteins, which is associated with events such as capacitation, hyperactivation and acrosome reaction that are essential for successful fertilization. Extensive studies were carried out on protein phosphorylation in relation to capacitation, but its role still remains ambiguous. 相似文献
Epidural anesthesia and analgesia are popular regional anesthetic techniques in many animal species. However, we have not found any reports of studies in animals that have investigated the extent of cephalad migration and level of sensory blockade achieved based only on the volume of drug injected into the epidural space. The purpose of this study was to determine if there is a relationship between the volume (mL/kg) of an injectate injected epidurally and the extent of its cephalad migration within the epidural space. Twelve adult goats were randomly assigned to three treatment groups based on the volume of 0.12% New Methylene Blue (NMB), 0.1, 0.2, or 0.3 mL/kg, injected into the epidural space. The site and speed of injection, animal position, and direction of needle bevel were held constant. All injections were performed at the lumbo-sacral space immediately following euthanasia. At necropsy, the vertebral columns were transected longitudinally. The extent of cephalad migration of dye within the epidural space was easily determined by staining of the dura. Measurements were rounded to the nearest intervertebral space to which the dye had migrated. The individual making assessments was blinded to all treatments. In goats treated with 0.1, 0.2, or 0.3 mL/kg NMB, the number of stained spinal segments was 3.5 ± 0.6, 6.5 ± 0.9, and 8.8 ± 0.6, (mean ± SEM), respectively. Linear regression performed on the data was significant ( P <.05) with R2= 0.86. There was a strong linear relationship between volume (mL/kg) of epidurally injected NMB and cranial migration, with the larger volumes producing more cephalad spread within the epidural space. These results provide evidence for the volume of epidural injectate needed to produce a desired level of sensory blockade in adult goats. 相似文献
An unusually high abundance of long‐finned squid (Loligo pealeii) was observed around southern Newfoundland in August–September 2000. The prevalence of maturing females and mature males, along with the collection of a single viable egg mop, provide the first evidence of spawning of this species at the northern limit of its geographic range of distribution. Northward expansion of the long‐finned squid population may be related to a general warming trend in Newfoundland near‐shore waters. However, trends in size and abundance of short‐finned squid (Illex illecebrosus) suggest that this expansion may also be related to reduced competition. We hypothesize that these two squid species share, to a large extent, a common niche on the eastern USA shelf and that opposing responses to ecosystem variation affect their relative abundance. We address this hypothesis by applying time‐series analysis of species‐specific fishery‐ and survey‐based abundance indices with biologic and environmental input variables. Our models indicate that direct competition is not important, but that variation in atmospheric forcing, as well as latitudinal position of the Shelf‐Slope Front (SSF), are closely related to direct oceanographic processes that exert opposing effects on these two species. While the direct oceanographic mechanisms that regulate year‐class strength remain unknown, we present a hypothesis to account for opposing population responses to oceanographic variation that operates early in the life history of both species. For the oceanic and highly migratory short‐finned squid, variation in the latitudinal position of the SSF is related to efficiency of downstream dispersal by the Gulf Stream and survival of young stages. For the neritic long‐finned squid, variation in local inshore temperature affects the time exposed to intense predation through its effect on rates of embryonic development and growth. The expansion of long‐finned squid population abundance in 2000 was associated with both warm local water temperatures and an unusual eastward displacement of the atmospheric features associated with the North Atlantic Oscillation (NAO). These conditions may have resulted in an unfavorable oceanic regime for short‐finned squid but a favorable regime for long‐finned squid on the continental shelf as far north as southern Newfoundland. 相似文献
We describe a fibrosarcoma in a 12-year-old Quarterhorse × Arabian gelding as a sequela to equine influenza vaccination. Shortly after the second vaccination, swelling at the site was noticed by the owner and it continued to increase in size over the following 6 months. Biopsy of the mass indicated a fibrosarcoma had developed at the vaccination site. It was approximately 20 cm in diameter and elevated well above the level of the skin. There was no clinical evidence of metastases to the lungs or local lymph nodes. Surgical resection of the mass was performed and the wound healed by first and second intention. Histopathological examination and immunohistochemical staining confirmed a myofibroblastic fibrosarcoma with multifocal osseous metaplasia. To the authors' knowledge, this is the first equine case of a vaccine-associated fibrosarcoma. 相似文献
AIMS: To evaluate a multivalent leptospiral and clostridial vaccine for prevention of renal colonisation and urinary shedding in sheep, following experimental challenge with New Zealand strains of Leptospira borgpetersenii serovar Hardjo type Hardjobovis and L. interrogans serovar Pomona.
METHODS: Two separate but similarly designed studies were conducted. In both studies, Romney-cross lambs, aged 9–11 weeks, were randomly allocated to a vaccinated group and a control group. Vaccinated lambs each received two 1.5-mL S/C doses of a multivalent leptospiral and clostridial vaccine, 4 weeks apart, and animals in the control groups received the same dose of saline. Groups of 12 vaccinated and 12 control lambs were randomly selected in each study for challenge with serovars Hardjo or Pomona. Challenge was initiated 16 weeks following the second vaccination with three daily doses of live leptospires by intranasal and conjunctival routes. Following challenge, urine samples were collected weekly for 6 weeks, for dark field microscopy and leptospiral culture; 6 weeks after challenge the lambs were slaughtered and kidneys collected for leptospiral culture.
RESULTS: In lambs challenged with serovar Hardjo, 8/12 unvaccinated lambs had ≥1 urine or kidney sample that was positive for leptospires following culture, compared with 0/12 lambs in the vaccinated group (p=0.001). In lambs challenged with serovar Pomona, 9/12 unvaccinated lambs had ≥1 urine or kidney sample that was positive following culture, compared with 0/12 lambs in the vaccinated group (p<0.001). Prevention of renal colonisation and urinary shedding, expressed as the prevented fraction, was 100 (95% CI=61.7–100)% and 100 (95% CI=68.3–100)% against challenge with serovars Hardjo and Pomona, respectively, at 4 months after vaccination.
CONCLUSIONS AND CLINICAL RELEVANCE: Use of a multivalent leptospiral and clostridial vaccine demonstrated protection against challenge from New Zealand strains of serovars of Hardjo and Pomona 4 months after vaccination in lambs first vaccinated at 9–11 weeks of age. Further studies are required to assess the duration of immunity against challenge in sheep. 相似文献