We present here a method for the regeneration of the prickly-pear (Opuntia ficus-indica (L.) Mill.) through somatic embryogenesis (SE). Direct SE was induced by cultivating shoot apices devoid of leaf primordia on semisolid Murashige and Skoog (MS) basal medium supplemented with 4-amino 3,5,6-trichloropicolinic acid (picloram) at 4 mg l−1. Somatic embryogenesis was influenced by the type, age, physiological and developmental stage of the explants, and also by light conditions, wounding, and the sucrose concentration in the induction medium. A histological analysis confirmed SE by revealing the presence of a closed vascular system in the developing embryos and the absence of a vascular connection between the somatic embryos and the explant. 相似文献
In this study, 98 Escherichia coli isolates from 42 diarrheic neonatal piglets were screened for the presence of cytolethal distending toxin coding gene by polymerase chain reaction (PCR). PCR yielded a single product which was specifically generated for E. coli cdt(+) control strain and not for other control strains. Twenty two (22.4%) of the isolates tested were cdtB positive, and 50% of the cdtB(+) isolates were also estII positive. The most prevalent pathotype was O32 cdtB(+) estII(+), which accounted for 59% of the cdtB positive strains. These results indicate an association between the presence of the cdtB gene and diarrhea, and support the need for further studies to determine the role of this toxin in diarrhea. 相似文献
The digestive system of the capybara has been investigated because of its coprofagia habits, important for their absorptive activity. These species present differences in terms of gastrointestinal morphological characters when compared with other rodents. Macroscopiclly, the stomach of the capybara is constituted of the following parts: cardiac, pyloric, body, fundic and gastric diverticulum. It presents two curvatures, one big and another small. Externally, the presence of gastric bands (tenias) is observed. With regards to the volumetric view, the gastric capacity varies from 850 to 2010 ml, with an average of 1498.57 ml. So, the stomach of this animal can be classified as a simple stomach, in the format of a curved sack and similar to an inverted letter 'J'. The gastric mucous membrane presents a surface filled by numerous tortuous gastric folds and longitudinally distributed along all its extension. The mucous tunic also possesses recesses located among the successive gastric folds, which were denoted as gastric parts with numerous openings described as gastric pits. In the cardiac part, a glandular epithelium with cardiac glands is noticed containing a lot of parietal and mucous neck cells. The fundic part, body and gastric diverticulum contain proper gastric glands with main, parietal and mucous neck cells. Finally, the pyloric part has pyloric glands with two cellular types, mucous neck and parietal cells. 相似文献
Approximately 0.2% (n=4397) of the bovids (cattle and buffalo) in Sri Lanka were sampled, from June 1992 using a multi-stage sampling procedure. Serum antibodies for the rinderpest virus were detected using the competitive enzyme-linked immunosorbent assay. The age, the agroclimatic zone, the management system practiced in the farms, and the vaccination history of the sampled bovids were studied as potential risk factors for being seropositive.
The prevalence of rinderpest antibodies in non-vaccinated bovids was 3.5% (n=4101). The prevalence was higher in the dry zone (9%; where the outbreak emerged in 1987), compared to bovids in the other zones (1%). Seropositive bovids over three years of age were approximately at fourfold higher chances of being seropositive compared to those that were ≤3 years old. The higher prevalence in older animals is probably due to exposure to the virus during the 1987 epidemic. Bovids from the dry zone (annual rainfall 20 to 35 inches) were at higher odds of being seropositive even after controlling for the possible effects of age, agroclimatic zone, management system and vaccination. The fact that 62% of bovids from the dry zone in this study were reared under extensive management system (free grazing) which allow unrestricted contact between animals, may be the reason for the above finding. A relatively poor response to vaccination observed in vaccinated bovids (seroprevalence=12%; n=296) could be attributed to difficulties in maintaining the vaccine at recommended temperatures in the field. This is the first island-wide study on seroprevalence of rinderpest in Sri Lanka. 相似文献
Sri Lankan black pepper with symptoms of yellow mottle disease contained a mixture of viruses: Piper yellow mottle virus (PYMV) particles (30 × 130 nm), Cucumber mosaic virus (CMV, 30 nm diameter isometric particles), and unidentified, isometric virus-like particles (30 nm diameter). An effective purification procedure is described for PYMV. Immunosorbent and conventional electron microscopy successfully detected badnavirus particles only when at least partially purified extracts were used. PYMV was confirmed as the cause of the disease, with the other two viruses apparently playing no part in producing symptoms. PYMV was transmitted by grafting, by the insect vectors citrus mealy bug ( Planococcus citri ) and black pepper lace bug ( Diconocoris distanti ), but not by mechanical inoculation or through seeds. The CMV isolate was transmitted to indicator plants by mechanical inoculation and by the vector Aphis gossypii , but not by Myzus persicae ; but neither mechanical nor insect transmission of CMV to black pepper was successful. A sensitive polymerase chain reaction assay was developed to detect PYMV in black pepper. 相似文献
Recent studies have shown that factors from adipose tissue influence and regulate the reproductive system. Hormones such as leptin and resistin are now known to regulate several reproductive processes. Adiponectin is the most abundant protein secreted by adipose tissue, and its circulating concentration is inversely related to adiposity and body mass index. Little is known about the involvement of adiponectin in reproduction. In the present study, the effect of recombinant adiponectin on the meiotic maturation and early embryo development in vitro was investigated, using porcine oocytes. Adiponectin receptors, AdipoR1 and AdipoR2, were found to be expressed in porcine oocytes and cumulus cells of both small and large follicles. Both AdipoR1 and AdipoR2 were immunolocalized to cumulus-oocyte complexes (COCs), oocytes, and early developing embryos. When included in oocyte maturation medium for 46 h, adiponectin significantly decreased the frequency of meiotic immature oocytes derived from large follicles (3-6 mm) but not from small follicles (<3mm). From studies of oocytes matured in the presence of adiponectin and mitogen-activated protein kinase (MAPK) pathway inhibitors MEK1 (PD98059), MEK1/2 (U0126), and p38MAPK (SB203580) it was concluded that adiponectin enhances oocyte maturation thought the p38MAPK pathway. Finally, a superior rate of embryo development to the blastocyst stage was achieved by embryos cultured in the presence of adiponectin. These results indicate that adiponectin has a positive effect on the meiotic maturation and in vitro embryo development of porcine oocytes and suggests a physiological role for this adipokine in early development in mammals. 相似文献
1. The purpose of this study was to assess the incorporation of retinol into quail egg yolk and cholesterol concentration in response to supplementation with different quantities of retinyl palmitate (600, 1200, 2400 and 4800 microg). 2. Supplementations were performed weekly for 4 weeks and the yolk retinol was measured using high performance liquid chromatography. 3. The results showed a progressive increase in the incorporation of retinol into the egg yolk in response to supplementation, reaching values 384% higher than control values. 4. At the end of supplementation we observed a significant decrease in egg yolk retinol concentrations with supplementations of 2400 and 4800 microg, the most enduring showing high retinol contents even after 3 weeks. 5. Supplementation increased egg weight but neither egg production nor cholesterol levels were significantly altered. 相似文献