Embryo Transfer in Anovulatory Recipient Mares Treated with Estradiol Benzoate and Long-Acting Progesterone

This study aimed to prepare anovulatory mares in anestrus or in the transitional period as embryo recipients. Ninety embryo-recipient mares were divided into two groups (G). G1 (n = 45) comprised animals in anestrus or in the transitional period; these animals were treated for 3 days (D) with 5, 3, and 2 mg of estradiol benzoate (intramuscular) on D0 (day of the donor's ovulation), D1, and D2 (after ovulation), respectively, followed by weekly application of 400 mg of long-acting progesterone (intramuscular) from D3 after ovulation (donor) until the 120th day of gestation. G2 (n = 45) comprised mares with normal estrous cycles. Plasma levels of progesterone (P₄) were measured on days D1, D2, D8, and D14. Sixty percent of the animals in G1 and 71.1% in G2 (P > .05) completed the pregnancy. On D8, there was no difference in P₄ levels between G1 and G2 animals, but there was a difference in P₄ levels on D14 (P < .05). It was concluded that anovulatory mares in anestrus or in the transitional period could be used as embryo recipients. The protocol was efficient and also considered an appropriate alternative to prepare the uterine environment for embryo transfer; long-acting progesterone administration kept P₄ levels high enough to maintain pregnancy until the 120th day and provided recipients during the time of the year when fewer mares were cycling and ovulating.     

Resistance to papaya ringspot virus in summer squash Cucurbita pepo L. introgressed from an interspecific C. pepo × C. moschata cross

Early infections of the papaya ringspotvirus-watermelon strain (PRSV-W) in summersquash Cucurbita pepo may causemarketable yield losses of up to 100%. Because control of the viral disease viamanagement of vector insects is notefficient, incorporation of PRSV-W geneticresistance into C. pepo cultivarswould be highly desirable. Althoughresistant accessions have been described inC. ecuadorensis, C.foetidissima, C. maxima and C.moschata, resistant accessions of C.pepo are rare. This paper reports oninterspecific hybridization between C.pepo and a PRSV-W-resistant C.moschata squash accession, and on theearly steps in introgression of thisresistance into the former species. C. pepo cv. Asmara was crossed with twoPRSV-W resistant C. moschataaccessions. Immature F₁ (C.pepo× C.moschata) embryos were excised20 days after pollination, and culturedasseptically in two different culturemedia, each under two different lightregimes. No adult plants could berecovered from immature embryos of thecross C. pepo cv. Asmara × C.moschata cv. Piramoita. From the crossC. pepo cv. Asmara × C.moschata cv. Duda, 4 seedlings wererecovered from 6 embryos incubated in agrowth chamber [25° to 28 °C,16 hours of light with 1500–2000 lux/ 8 hdark period] immediately after excision andinoculation in a culture medium [=Murashige and Skoog (MS) + 0.01 mg/L of IAA(indolacetic acid) + 0.1 mg/L of Kinetin],without an intervening dark period. F₁ (C. pepo × C. moschata)plants were fertile, and upon selfingyielded viable F₂ seeds. PRSV-Wresistance was assessed in the F₂ (C. pepo × C. moschata) population,using C. pepo cv. Asmara and C.moschata cv. Duda, respectively, as thesusceptible and resistant (tolerant)checks. Plants were mechanically inoculatedwith a known PRSV-W isolate. The F₂population showed a PRSV-W responseintermediate between those of the parentalaccessions, and estimates of the meandegree of dominance indicates incompletedominance in the direction ofsusceptibility. The mean broad-senseheritability estimate of PRSV-W resistancewas 0.48, a medium to high value,indicating the likelihood of a significantresponse to selection for resistance. Theintrogression of the resistance to PRSV-Wof C. moschata into C. peposeems to be technically viable.     

Larvicidal Potential of the Halogenated Sesquiterpene (+)-Obtusol,Isolated from the Alga Laurencia dendroidea J. Agardh (Ceramiales: Rhodomelaceae), against the Dengue Vector Mosquito Aedes aegypti (Linnaeus) (Diptera: Culicidae)

Dengue is considered a serious public health problem in many tropical regions of the world including Brazil. At the moment, there is no viable alternative to reduce dengue infections other than controlling the insect vector, Aedes aegypti Linnaeus. In the continuing search for new sources of chemicals targeted at vector control, natural products are a promising alternative to synthetic pesticides. In our work, we investigated the toxicity of a bioactive compound extracted from the red alga Laurencia dendroidea J. Agardh. The initial results demonstrated that crude extracts, at a concentration of 5 ppm, caused pronounced mortality of second instar A. aegypti larvae. Two molecules, identified as (−)-elatol and (+)-obtusol were subsequently isolated from crude extract and further evaluated. Assays with (−)-elatol showed moderate larvicidal activity, whereas (+)-obtusol presented higher toxic activity than (−)-elatol, with a LC₅₀ value of 3.5 ppm. Histological analysis of the larvae exposed to (+)-obtusol revealed damage to the intestinal epithelium. Moreover, (+)-obtusol-treated larvae incubated with 2 µM CM-H₂DCFDA showed the presence of reactive oxygen species, leading us to suggest that epithelial damage might be related to redox imbalance. These results demonstrate the potential of (+)-obtusol as a larvicide for use against A. aegypti and the possible mode of action of this compound.     

Variability of the nitrifying bacteria in the biofilm and water column of a recirculating aquaculture system for tilapia (Oreochromis niloticus) production

The aim of this study was to evaluate variability of nitrifying bacterial community in the biofilm and in the water of a recirculating aquaculture systems (RAS) in a tilapia farming in order to determine if nitrification process is dependent, or not, of nitrifying bacteria abundance. Biofilm and water samples were collected periodically for 30 days and analysed with the fluorescent in situ hybridization (FISH) technique, used to quantify ammonia‐oxidizing bacteria (AOB) and nitrite‐oxidizing bacteria (NOB). Ammonia presented the peak in the first week, while the nitrite's maximum was recorded in the second week. Nitrate increased steadily, indicating nitrification activity. Total bacterial abundance in biofilm increased continuously, while in water, it did not change significantly. In the biofilm, number of AOB was high at beginning, decreased after few days and increased again following augment of ammonia. Number of NOB also showed an increase in abundance in biofilm following the increment of nitrite and nitrate. In water, AOB and NOB did not show major variability. Relative abundance of nitrifying bacteria represented more than 30% of total bacteria in biofilm at beginning of the experiment. Their contribution decreased to >3% in last days. It indicates that nitrifying bacteria are biofilm colonizers, and that their activity seems to be directly related to the concentration of nitrogen compounds. However, contribution of nitrifying bacteria did not vary much along the time. We may conclude that the biofilm‐nitrifying bacteria plays major role in nitrification process in RAS and that the activity of these organisms is dependent of their abundance in response to the concentration of nitrogen compounds.     

A survey of neurological diseases in horses

SUMMARY: Case records of 450 horses with signs of neurological disease are reviewed. One hundred and nineteen horses with neurological disease due to trauma were examined, of which 60 were due to spinal cord trauma, 47 to brain or cranial nerve trauma and 12 to peripheral nerve trauma. Cervical vertebral fractures/trauma were the most common injury. Basisphenold/basloccipital bone fractures were the most common form of cranial trauma and facial nerve paralysis the most common cranial nerve injury. Eighty-nine horses with neurological disease due to malformation were examined. Cervical vertebral malformation occurred in 83 horses and congenital defects in 6 foals. Neurological disease due to inflammation or infection occurred in 30 horses. The most common disease of this type was meningitis, which occurred in 11 horses and foals. Neoplasms in the CNS caused neurological disease in 8 horses. The final category was miscellaneous neurological disease, which was diagnosed in 204 horses. Diseases in this category included neonatal (28 cases), toxic/metabolic (27 cases), idiopathic (133 cases), degenerative (3 cases) and other neurological diseases (13 cases). The most common condition was idiopathic laryngeal hemiplegia (116 cases).
Where possible, diagnosis relied on a thorough neurological examination with use of ancillary tests in selected cases including rhinolaryngoscopy, radiography, myelography, ophthalmoscopy and cerebrospinal fluid analysis when indicated. In many cases necropsy and histopathological confirmation or diagnosis was necessary.     

Strategic use of crutching and dicyclanil to protect unmulesed sheep against breech strike

Objective   To test strategies for the application of dicyclanil and mid-season crutching to maximise protection of unmulesed sheep against breech strike.
Procedure   Three hundred and eighty unmulesed Merino weaners were randomly allocated to four groups either left untreated or treated by different strategies with 50 g/L dicyclanil. Treatments included breech treatment alone and breech plus body treatment, with two application times, immediately after shearing and 6 weeks after crutching or shearing. To assess protection, larval implants with newly hatched Lucilia cuprina larvae were applied to 10 different sheep from each group at 3, 4, 5 and 6 months after crutching and shearing and assessed for the development of strike at 48 hours. The concentration of dicyclanil was measured in wool samples clipped from the breeches of the test sheep.
Results   All dicyclanil treatments gave significant reduction in strike in comparison to controls up until 4 months after crutching but protection in the sheep treated immediately after shearing had waned at 5 months. Treating at 6 weeks after crutching provided significant reduction ( P < 0.05) in strike for 6 months. Results for strike incidence immediately after shearing and concentration of dicyclanil in the breech wool also suggested improvements in protection by delaying treatment for 6 weeks.
Conclusion   In most environments it should be possible to protect unmulesed sheep against breech strike with a carefully planned integrated control program incorporating strategically timed crutching, shearing and dicyclanil application. Delaying treatment with dicyclanil to at least 6 weeks after shearing or crutching increased the protection provided in comparison to treatment immediately after shearing.     

Cadmium Effects on Sunflower Growth and Photosynthesis

The objective of this work was to evaluate the effects of cadmium (Cd) exposure on sunflower (Helianthus annuus L.) plant growth, chlorophyll content, and fluorescence. Sunflower plants were exposed to different concentrations of Cd (0, 5, 50, and 500 μ M) for 21 d. Growth parameters (organ length, fresh and dry weights) were determined and results compared with two parameters associated with photosynthesis degradation: chlorophyll content and fluorescence (an easy and non-destructive method). Exposure to Cd significantly decreased growth by decreasing shoot and root lengths and their fresh and dry weight. Cadmium also decreased significantly chlorophyll content and fluorescence efficiency in all treatments. Chlorophyll a (chl a) and chl b contents showed a significant correlation with chlorophyll fluorescence (F_v/F_m ratio). The EC₅₀ values showed that the roots' length was the most sensitive endpoint in this study, followed by the roots' and shoots' weight endpoints. Also, chl b showed higher sensitivity to Cd contamination than chl a. These data show that in complement to growth parameters, the use of photosynthetic parameters provides helpful information on plant response to Cd exposure.