Getting cosy in freshwater: Assumed to be brackish pike are not so brackish after all

Pike (Esox lucius) occupy coastal streams and rivers of the Baltic Sea, where they attain large sizes (>5 kg). These large sizes are perhaps due to the fact that they can tolerate relatively high salinities and can thus forage in the nearby more productive brackish environments. In an attempt to quantify the extent to which pike utilise brackish environments, and to provide some insight into the underlying causes for brackish water migrations, we tagged 30 pike from a western Baltic river with acoustic transmitters and were able to track 21 individuals for 1 year. Based on experienced from local anglers, this population was assumed to be brackish in nature, where individuals underwent freshwater migrations to spawn. Our findings however suggest that the smallest and most active individuals make short exits into brackish waters and do so on rare occasions. Our results further indicate that neither sex nor size is related to activity level. We suggest that these patterns reflect two distinct behaviours—active and passive—and that large pike can be supported by the food availability in the river, without the need to venture into coastal zones, thus defying the conventional view that Baltic pike are all brackish in nature.     

γ-Amino Butyric Acid Control of Arginine Vasopressin Release from the Ewe Hypothalamus In Vitro: Sensitivity to Oestradiol

The present study aims to ascertain the influence of gamma-amino butyric acid (GABA)(A or B) receptors on arginine vasopressin (AVP) release in vitro and determine whether E(2) modulates GABA-AVP interaction. Within 10 min of ewe killing, saggital midline hypothalamic slices (from the anterior preoptic area to the mediobasal hypothalamus along with the median eminence, 2-mm thick, two per ewe) were dissected, placed in oxygenated minimum essential media (MEM)-alpha at 4 degrees C and within 2 h were singly perifused at 37 degrees C with oxygenated MEM-alpha (pH 7.4; flow rate 0.15 ml/min), either with or without E(2) (24 pg/ml). After 4-h equilibration, 10-min fractions were collected for 4 h interposed with a 10-min exposure at 60 min to a specific GABA(A or B) receptor agonist or antagonist at various doses (0.1-10 mm). GABA(A) (muscimol; no E(2), n = 7 perifusion chambers, with E(2), n = 11) or GABA(B) (baclofen; no E(2), n = 8, with E(2), n = 15) agonists (10 mm) did not influence AVP concentrations. However, AVP release increased (p < 0.05) 20-30 min after exposure to 10 mm GABA(A or B) antagonists (bicuculline, no E(2), n = 7: from 4.6 +/- 0.7 to 33.0 +/- 0.4, with E(2), n = 17: from 11.9 +/- 1.4 to 32.8 +/- 6.0; CGP52432, with E(2), n = 14: from 14.0 +/- 2.6 to 28.8 +/- 3.9 pg/ml). At the end of the collection period, hypothalamic slices responded to KCl (100 mm) with AVP efflux (p < 0.05). GABA(B) but not GABA(A) antagonist-stimulated AVP release was enhanced in the presence of E(2). In summary, AVP release is under the inhibitory influence of GABA input with further potentiation by E(2) through GABA(B) receptors in vitro.     

Immunolocalization of Aquaporins 1 and 9 in the Ram Efferent Ducts and Epididymis

Aquaporins (AQPs) are essential membrane protein channels for the transport of water across membranes. Fluid movement in the epididymis is important for modulation of the luminal environment, in which sperm mature and reside. This study was designed to understand the morphology and localization of AQPs in ram efferent ducts (ED) and epididymis. For this purpose, the epididymis of seven animals were removed for histologic and immunohistochemical analyses. AQP1 immunoreactivity was observed in the apex of the ED, and AQP9 was found adjacent to the nuclei of the epithelial cells of the ED. The epithelial lining of ram epididymis is pseudostratified columnar and presents principal, basal, apical and narrow cells. In the initial segment (IS), a moderate reaction for AQP1 was observed in the apical cytoplasm of epithelial cells. An intense reactivity for AQP1 was noted over the microvilli of principal cells and in spermatozoa in the caput. In the corpus and cauda, AQP1 was noted only over the endothelial cells of vascular channels located in intertubular spaces. A weak‐to‐moderate reaction for AQP9 was observed in the nuclei of epithelial cells in the IS, caput and corpus of the epididymis. In the cauda, an intense reaction to AQP9 was observed in the epithelial border. In the IS, caput and corpus, the reactivity for AQP9 differed from those observed in domestic animals. The cauda showed a pattern similar to that previously described. These results indicate that AQPs 1 and 9 have reversed locations and roles in rams, suggesting activity variations related with fluid and solute absorption throughout the epididymis.     

Kisspeptin,c‐Fos and CRFR Type 2 Co‐expression in the Hypothalamus after Insulin‐Induced Hypoglycaemia

Normal reproductive function is dependent upon availability of glucose and insulin‐induced hypoglycaemia is a metabolic stressor known to disrupt the ovine oestrous cycle. We have recently shown that IIH has the ability to delay the LH surge of intact ewes. In the present study, we examined brain tissue to determine: (i) which hypothalamic regions are activated with respect to IIH and (ii) the effect of IIH on kisspeptin cell activation and CRFR type 2 immunoreactivity, all of which may be involved in disruptive mechanisms. Follicular phases were synchronized with progesterone vaginal pessaries and at 28 h after progesterone withdrawal (PW), animals received saline (n = 6) or insulin (4 IU/kg; n = 5) and were subsequently killed at 31 h after PW (i.e., 3 h after insulin administration). Peripheral hormone concentrations were evaluated, and hypothalamic sections were immunostained for either kisspeptin and c‐Fos (a marker of neuronal activation) or CRFR type 2. Within 3 h of treatment, cortisol concentrations had increased whereas plasma oestradiol concentrations decreased in peripheral plasma (p < 0.05 for both). In the arcuate nucleus (ARC), insulin‐treated ewes had an increased expression of c‐Fos. Furthermore, the percentage of kisspeptin cells co‐expressing c‐Fos increased in the ARC (from 11 to 51%; p < 0.05), but there was no change in the medial pre‐optic area (mPOA; 14 vs 19%). CRFR type 2 expression in the lower part of the ARC and the median eminence was not altered by insulin treatment. Thus, disruption of the LH surge after IIH in the follicular phase is not associated with decreased kisspeptin cell activation or an increase in CRFR type 2 in the ARC but may involve other cell types located in the ARC nucleus which are activated in response to IIH.     

Evaluation of trypanosomiasis control alternatives using an epidemiologic simulation model

The effect of various disease-vector control alternatives on the prevalence of trypanosomiasis in southwest Ethiopia was examined with the aid of an epidemiologic model. The alternatives considered included vegetation clearing by manual labor, game elimination, insecticidal spraying from airplanes coupled with settlement, use of sterile male Glossina, avoidance of tsetse infested areas, increasing the resistance of the cattle population, therapy, and combinations of the above methods. First, the currently estimated endemic prevalence of trypanosomiasis (27.3%) in the simulated area of Ethiopia was established and maintained over a 10 year period. Then, various control alternatives were introduced and the simulation was run for an additional 10 years to observe the effect of these control alternatives on the prevalence. The combined use of vegetation clearing, insecticides, therapy, and settlement (or resettlement) was the most effective and feasible method of trypanosomiasis control for the simulated situation.     

Biological, seasonal and environmental factors associated with Pulex irritans infestation of dairy goats in Greece

The objectives of the present study were to study the fauna of fleas infesting dairy goats in Greece, the spectrum of hosts each flea species infests, identify risk factors in the environment, and goat management practices that favour flea infestation of goats, and describe the seasonal variation of infestation in goats. For this purpose, a total of 64 herds, with a history of flea infestation in goats, were visited during June and July of 2002 for data collection on flea burdens, species of fleas on goats, and other farm or pet animal species in the farm. Also data were collected on herd characteristics and management along with the flea infestation status of the village where it was located through a questionnaire survey. Data on elevation and climatic characteristics of the villages where the herds were located were also used in the study. All fleas collected from goats, sheep, pigs, and cattle were identified as being Pulex irritans. All fleas collected from cats were identified as being Ctenocephalides felis. Dogs were infested either with P. irritans, C. canis, or C. felis, or with both C. canis and C. felis. Kids had a significantly higher flea burden than goats and the Skopelos breed had the highest flea burden of all breeds followed in diminishing order by the breeds Capra prisca, Saanen cross mix, and Alpine cross mix (p < 0.05). The gender of the animal had no significant effect on flea burden. Factors significantly affecting the flea burden of goats were duration of flea infestation in the herd, type of flea control, and manure imported prior to the appearance of fleas in the herd (p < 0.05). The flea burden of goats was highest during summer and lowest during winter (p < 0.01), with complete an absence of infestation in January and February. Finally, a significant difference (p < 0.05) was found between the average annual temperature of villages with flea infestation (15.59 degrees C) and villages without flea infestation (17.14 degrees C). It was concluded that P. irritans was a true infestation of goats in Greece.     

What happens after technology adoption? Gendered aspects of small-scale irrigation technologies in Ethiopia,Ghana, and Tanzania

Diverse agricultural technologies are promoted to increase yields and incomes, save time, improve food and nutritional security, and even empower women. Yet a gender gap in technology adoption remains for many agricultural technologies, even for those that are promoted for women. This paper complements the literature on gender and technology adoption, which largely focuses on reasons for low rates of female technology adoption, by shifting attention to what happens within a household after it adopts a technology. Understanding the expected benefits and costs of adoption, from the perspective of women users in households with adult males, can help explain observed technology adoption rates and why technology adoption is often not sustained in the longer term. Drawing on qualitative data from Ethiopia, Ghana, and Tanzania, this paper develops a framework for examining the intrahousehold distribution of benefits from technology adoption, focusing on small-scale irrigation technologies. The framework contributes to the conceptual and empirical exploration of joint control over technology by men and women in the same household. Efforts to promote technology adoption for agricultural development and women’s empowerment would benefit from an understanding of intrahousehold control over technology to avoid interpreting technology adoption as an end in and of itself.     

The Effect of a Chronic Stressor, Lameness, on Detailed Sexual Behaviour and Hormonal Profiles in Milk and Plasma of Dairy Cattle

The objectives of the present study were to quantify the effects of a biological chronic stressor (lameness) on the duration and frequency of different oestrous behaviours in parallel with milk hormone profiles. Dairy cows 51.8 ± 1.4 days postpartum (n = 59), including 18 non‐lame control cows, were scored for lameness and closely observed for signs of oestrus having had their follicular phases synchronized by administration of gonadotrophin‐releasing‐hormone (GnRH) followed by prostaglandin F_2α (PG) 7 days later. Lameness shortened the period when herd‐mates attempted to mount the lame cows (1.83 ± 0.69 h vs 5.20 ± 1.53 h; p = 0.042) but did not affect the overall duration of total behaviours (lame 12.3 ± 1.3 h vs non‐lame 15.2 ± 1.3 h). Lameness also lowered the intensity of oestrus [1417 ± 206 points (n = 18) vs 2260 ± 307 points (n = 15); p = 0.029]. Throughout the synchronized oestrous period, lame cows mounted the rear of herd‐mates less frequently (p = 0.020) and tended to chin rest less (p = 0.075). Around the period of maximum oestrous intensity, lameness also diminished the proportion of cows mounting the rear of another cow and chin resting (p = 0.048, p = 0.037, respectively). Furthermore, lame cows had lower progesterone values during the 6 days before oestrous (p ≤ 0.05). Fewer lame cows were observed in oestrus following PG (non‐lame 83%, lame 53%; p = 0.030); however, if prior progesterone concentrations were elevated, lame cows were just as likely to be observed in oestrus. In conclusion, following endogenous progesterone exposure, lameness shortens the period when herd‐mates attempt to mount lame cows but does not affect the incidence of oestrous. However, lame cows are mounted less frequently and express oestrus of lower intensity. This is associated with lower progesterone prior to oestrus but not with abnormal oestradiol or cortisol profiles in daily milk samples.     

Dirofilaria immitis infection in dogs from underserved, Native American reservations in the United States

Blood samples from 1,822 dogs residing on Native American reservations in 10 states were collected between February 2004 and August 2007. Samples were examined using a commercial enzyme-linked immunosorbent assay (ELISA) antigen capture test. All ELISA-positive samples were subsequently examined for microfilaremia. All dogs were asymptomatic for Dirofilaria immitis infection, resided outside (except for winter in the Northern latitudes), not on prophylaxis for D. immitis, and had not traveled off of the reservation. Reservations were characterized by degrees of north latitude, true prevalence of D. immitis, and a reproductive index calculated by multiplying the number of months of the year in which infective stage larvae (L(3)) could develop in 30 days or less for each reservation by the 30 yr mean annual rainfall in centimeters recorded for that community. The prevalence of heartworm was directly related to the reproductive index on each reservation.