The Effects of Isoflavones on Androgens and Glucocorticoids During Puberty on Male Wistar Rats

Isoflavones are the most common phytoestrogens found in human diets. However, it is still not clear whether isoflavones have effects on the reproductive and the endocrine systems under normal dietary intake and overdose. The aim of this study was to determine how the most important isoflavones, genistein and daidzein, affect androgen and glucorticoid levels on male prepuberal rats. A hundred and seventy‐five 30‐day‐old male Wistar rats were dosed orally by stomach tube every day for 35 days, with saline solution, low and high doses of genistein, daidzein and a mixture of both. Serum samples were analysed by an enzyme immunoassay for hormone determinations. In control group, there was a peak of testosterone (T) and dihydrotestosterone levels associated to the onset of puberty, at the third week. However, in low‐dose groups, the same peak was found at the fourth week (p < 0.05), indicating a delay in the onset of puberty in these groups. Moreover, high doses groups serum androgen levels were significantly lower (p < 0.05) than the control group from the first week until fifth week. This fact was supported by a epididymal histological analysis that indicate in low doses there were several content of spermatozoa at fourth week and in high doses there were few content of spermatozoa. Besides, corticosterone levels followed the same pattern of androgens in all groups. We can conclude that oral administration of isoflavones in male rats decreased the secretion of androgens and glucocorticoids causing a delay in the onset of puberty and may cause physiological and developmental problems.     

Effects of inflammation-associated acute-phase response on hepatic and renal indices in the horse

Objectives To determine the effect of an acute soft tissue inflammatory response on biochemical and haematological indices of hepatic and renal function in the Thoroughbred horse.
Procedure Soft tissue inflammation was induced in four Thoroughbred horses by intramuscular injections of Freunds complete adjuvant. The horses were clinically examined and blood and urine samples were collected before and after the adjuvant injections. Biochemical and haematological indices were measured in samples collected and used to determine the onset of the acute-phase response and to assess hepatic and renal function at this time.
Results After adjuvant injection, significant increases (P< 0.01) in total white (13.1 ± 1.4 times 10⁹/L) and neutrophil (10.2 ± 1.2 times109/L) cell counts, rectal temperature (39.7 ± 0.5A°C) and various plasma protein concentrations, including fibrinogen (6.6 ± 1.2 g/L), haptoglobin (1.3 ± 0.1 g/L) and total protein (88.1 ± 2.7 g/L), indicated the induction of an acute-phase response. This corresponded with significant reductions (P< 0.01) in the plasma elimination half-lives (t½β) sodium bromo-sulphthalein (3.13 ± 0.05 to 2.82 ± 0.07 min) and sodium sulphanilate (38.29 ± 4.04 to 19.60 ± 5.68 min) and reductions in the plasma activities of aspartate aminotransferase, gluta-mate dehydrogenase, creatine kinase, alkaline phosphatase, gamma glutamyl transferase; the urinary creatinine clearance ratios of sodium, chloride and potassium; and the urinary gamma glutamyl transferase-to-creatinine clearance ratios. (All values mean ± SD.)
Conclusions The effects of the acute-phase response on indices of hepatic and renal function in the horse suggest that the disposition of pharmacological agents administered at this time may be altered and that indices of acute inflammation should be interpreted cautiously.     

The effect of two pre-cryopreservation single layer colloidal centrifugation protocols in combination with different freezing extenders on the fragmentation dynamics of thawed equine sperm DNA

Background

Variability among stallions in terms of semen cryopreservation quality renders it difficult to arrive at a standardized cryopreservation method. Different extenders and processing techniques (such us colloidal centrifugation) are used in order to optimize post-thaw sperm quality. Sperm chromatin integrity analysis is an effective tool for assessing such quality. The aim of the present study was to compare the effect of two single layer colloidal centrifugation protocols (prior to cryopreservation) in combination with three commercial freezing extenders on the post-thaw chromatin integrity of equine sperm samples at different post-thaw incubation (37°C) times (i.e., their DNA fragmentation dynamics).

Results

Post-thaw DNA fragmentation levels in semen samples subjected to either of the colloidal centrifugation protocols were significantly lower (p<0.05) immediately after thawing and after 4 h of incubation at 37°C compared to samples that underwent standard (control) centrifugation. The use of InraFreeze® extender was associated with significantly less DNA fragmentation than the use of Botu-Crio® extender at 6 h of incubation, and than the use of either Botu-Crio® or Gent® extender at 24 h of incubation (p<0.05).

Conclusions

These results suggest that single layer colloidal centrifugation performed with extended or raw semen prior to cryopreservation reduces DNA fragmentation during the first four hours after thawing. Further studies are needed to determine the influence of freezing extenders on equine sperm DNA fragmentation dynamics.     

Do landscape and riverscape shape genetic patterns of the Neotropical otter,Lontra longicaudis,in eastern Mexico?

Context

Functional connectivity of semiaquatic species is poorly studied despite that freshwater ecosystems are amongst the most threatened worldwide due to habitat deterioration. The Neotropical otter, Lontra longicaudis, is a threatened species that represents a good model to evaluate the effect of landscape-riverscape features on genetic structure and gene flow of freshwater species.

Objectives

We aimed to assess the spatial genetic structure of L. longicaudis and to evaluate the landscape-riverscape attributes that shape its genetic structure and gene flow at local sites (habitat patches) and between sites (landscape matrix).

Methods

We conducted the study in three basins located in Veracruz, Mexico, which have a high degree of ecosystem deterioration. We used a non-invasive genetic sampling and a landscape genetics individual-based approach to test the effect stream hierarchical structure, isolation-by-distance, and isolation-by-resistance on genetic structure and gene flow.

Results

We found genetic structure that corresponded to the latitudinal and altitudinal heterogeneity of the landscape and riverscape, as well as to the hierarchical structure of the streams. Open areas and steep slopes were the variables affecting genetic structure at local sites, whereas areas with suitable habitat conditions, higher ecosystem integrity and larger streams enhanced gene flow between sites.

Conclusions

The landscape-riverscape characteristics that maintain functional connectivity of L. longicaudis differed between the upper, middle, and lower basins. Our results have important implications for the conservation of the species, including the maintenance of larger suitable areas in Actopan and the necessity to improve connectivity in Jamapa, through the establishment of biological corridors.

     

Natural progression of Bovine Leukemia Virus infection in Argentinean dairy cattle

We describe the progression of Bovine Leukemia Virus (BLV) infection from birth until the first lactation in 61 animals from a typical large dairy herd of Argentina, with more than 85% of prevalence. The purpose was to identify potential points to effectively break the BLV cycle of transmission in our dairy productive system. We detected early infection in 11.47% of newborn calves by nested PCR. From birth to 12 months, no evidence of new infections was observed. After 12 months of age, the detection of new reactors increased slowly with time, from 15.09% at 15 months to 24% at 27 months. After that, the number of reactors increased rapidly up to 40% and 60.76% at 30 and 36 months, respectively. This last 9-month period coincided with parturition and the entry into the milking herd. Real-time PCR showed that more than 75% of adult animals had low peripheral-blood proviral load. Complementary, all infected animals showed low levels of provirus in milk and colostrum. The most important finding was that even when management procedures to prevent BLV iatrogenic transmission were followed, no significant change was observed in the prevalence after three years, strongly suggesting that other way/s of transmission play a key role under natural conditions. This study showed an interesting baseline to draw an alternative approach based on selective segregation according to the peripheral-blood proviral load as a potential indicator of risk transmission, and as an alternative to classical control measures.     

Environmentally friendly treatment alternatives to Bordeaux mixture for controlling bacterial apical necrosis (BAN) of mango

Bacterial apical necrosis (BAN), caused by the bacterium Pseudomonas syringae pv. syringae (Pss), is currently the most limiting disease affecting the mango crop in the Mediterranean area. The copper‐based compound Bordeaux mixture (BM) is considered to be the conventional treatment against BAN, but it does not act as a bactericide. Alternative experimental treatments to BM that are compatible with organic farming were tested for their ability to control BAN disease. Field trials were conducted over six seasons in different mango orchards with natural infestation of Pss. The experimental treatments included applications of Silicon gel (a commercial formulation of aqueous potassium silicate), dicalcium phosphate, Kaolinite, and Ulmasud B^® (bentonite, powder); BM was applied as the conventional treatment. During the first two seasons (small‐scale trial, 2002–2004), all these experimental compounds were applied in order to select those treatments providing the greatest reduction of BAN symptoms. In the next three seasons (2005–2008), a semi‐commercial scale trial was carried out with the best‐performing treatments, resulting in the selection of Silicon gel. Finally, Silicon gel was tested in a commercial scale trial during the last season (2008–2009). Trees treated with Silicon gel showed significantly fewer necrotic buds and leaves, reaching disease levels very similar to those using the conventional treatment with BM. However, minor differences in P. syringae‐like population levels were observed, as has been described in previous studies. The possible mode of action of the Silicon gel is discussed. Currently, the Silicon gel compound is undergoing the registration process for its commercial use in mango management in Spain.     

Serum and Tissue Steroid Hormone Levels in Canine Mammary Tumours: Clinical and Prognostic Implications

Hormonal dependency of canine mammary tumours (CMT) has been studied over the last few decades. However, studies assessing the prognostic and predictive potential of serum and/or tissue steroid hormone levels are still scarce in CMT. To the best of our knowledge, this is the first report relating serum and tissue levels of steroid hormones and prognosis in dogs. Serum and tumour tissue from 45 female dogs with spontaneous CMT were included in the study. Moreover, serum and normal mammary tissue from 13 healthy female dogs were also included as controls. Steroid hormones were determined by competitive enzyme immunoassay. Overall, levels of steroid hormones in serum and tissue homogenates were significantly different between malignant and benign mammary tumours (p < 0.01), except for progesterone (P4) serum levels that revealed no statistical differences between groups. In malignant tumours, oestrone sulphate (SO4E1), dehydroepiandrosterone (DHEA), androstenedione (A4), testosterone (T) and P4 elevated tissue concentrations were significantly associated with tumour relapse and/or distant metastasis during follow‐up. A significant association was found between elevated tissue SO4E1 (p = 0.003), 17β‐oestradiol (E2) (p = 0.036), DHEA (p = 0.022), A4 (p = 0.001) and P4 (p = 0.013) concentrations and shorter disease‐free survival and overall survival in female dogs with malignant mammary tumours. The high levels of tissue steroids found in cases of poor prognosis open the possibility of additional new therapeutic approaches. Future clinical trials will be needed to clarify the usefulness of targeting steroid hormones in the treatment of this neoplastic disease.