Genetic interpretations of the effects of bulk breeding on four populations of beans (Phaseolus vulgaris L.)

Summary The effects of bulk breeding on yield and its components in two high-yeilding and two low-yielding bean populations when grown at crop densities are interpreted in terms of gene action and selection. There was considerable additive variation in the crosses, dominance effects were variable but tended to be negative. The results were compared with results obtained at low density by another worker with the same populations, and this showed that interpretations of gene action in hybrid vigour depend on the test environment used. The interpretations were also compared with plant breeding interpretations made on the same material (Hamblin, 1977), and it was found that a single pattern of response to natural selection, in plant breeding terms, may be explained by more than one genetic interpretation and, conversely, a single genetic interpretation may result in different patterns of response in plant breeding terms. The value of composite crosses in plant breeding are discussed and it is concluded that there is a greater chance of producing improved lines from a large number of simple crosses than from a smaller number of composite crosses.     

Trajectory shifts in the Arctic and subarctic freshwater cycle

Manifold changes in the freshwater cycle of high-latitude lands and oceans have been reported in the past few years. A synthesis of these changes in freshwater sources and in ocean freshwater storage illustrates the complementary and synoptic temporal pattern and magnitude of these changes over the past 50 years. Increasing river discharge anomalies and excess net precipitation on the ocean contributed approximately 20,000 cubic kilometers of fresh water to the Arctic and high-latitude North Atlantic oceans from lows in the 1960s to highs in the 1990s. Sea ice attrition provided another approximately 15,000 cubic kilometers, and glacial melt added approximately 2000 cubic kilometers. The sum of anomalous inputs from these freshwater sources matched the amount and rate at which fresh water accumulated in the North Atlantic during much of the period from 1965 through 1995. The changes in freshwater inputs and ocean storage occurred in conjunction with the amplifying North Atlantic Oscillation and rising air temperatures. Fresh water may now be accumulating in the Arctic Ocean and will likely be exported southward if and when the North Atlantic Oscillation enters into a new high phase.     

Possible adverse reaction to droncit in a miniature poodle

Abstract

Extract

Madam:— The N.Z.V.A. Nominee on the National Hydatids Council, Mr Peter Malone, in his annual report states that he knows of “no professional concerns that would allow certificates to be issued to exempt dogs from dosing with droncit, and on receipt of copies of such certificates will continue to forward them to the Veterinary Council to examine for disciplinary action”. (1 1985. Report of the N.Z.V.A. Nominee on the National Hydatids Council: N.Z.V.A. Annual Report 43–43.  [Google Scholar] In September 1985 I examined a nine year old miniature poodle dog that had been dosed with droncit by a hydatids control officer two hours previously. The dog had collapsed into lateral recumbancy, was pale and cyanotic with a rectal temperature of 37.3°C. Cardiac and thoracic auscultation was normal, and no other abnormal clinical signs were detected. There was no previous history of similar episodes and the dog has been dosed with droncit several times beforehand without problems. The dog was treated with betamethasone and millophylline and made a full recovery within 48 hours.     

Retrospective evaluation of sildenafil citrate as a therapy for pulmonary hypertension in dogs

Pulmonary arterial hypertension (PH) is a pathologic condition in dogs characterized by abnormally high pressures in the pulmonary circulation and has been associated with a poor outcome. Sildenafil is a type V phosphodiesterase inhibitor that produces nitric oxide mediated vasodilatation. Sildenafil treatment decreases pulmonary arterial pressure and pulmonary vascular resistance in people with PH. The purpose of this study was to describe the clinical characteristics and outcome of dogs with PH treated with sildenafil. The cardiology database was searched for dogs with PH treated with sildenafil. PH was defined as systolic pulmonary arterial pressure (PAPs) > or = 25 mmHg at rest. Medical records were reviewed for the following information: signalment, duration and type of clinical signs before treatment, underlying disease, estimated or measured PAPs, dosage and dosing interval of sildenafil, and the effect of treatment on clinical signs and pulmonary arterial pressure and survival time. Thirteen affected dogs were identified. Clinical signs included collapse, syncope, respiratory distress, and cough. Duration of clinical signs before presentation ranged from 3 days to 5 months. An underlying cause was identified in 8 dogs. The median sildenafil dosage was 1.9 mg/kg. Ten dogs received concurrent medications. Median PAPs was 90 mmHg; 8 dogs were reevaluated after therapy, and the median decrease in PAPs was 16.5 mmHg. The median survival time of all dogs was 91 days. Sildenafil appeared to be well tolerated in dogs with PH and was associated with decreased PAPs and amelioration of clinical signs in most. Sildenafil represents a reasonable treatment option for dogs with pulmonary hypertension.     

Intestinal immunomodulation by vitamin A deficiency and lactobacillus-based probiotic in Eimeria acervulina-infected broiler chickens

In a 2 X 2 factorial study, a broiler starter ration was amended for vitamin A (control, C; deficient, A) and probiotic status (-, P) to investigate their modulatory effects onthe host immune system. Birds were inoculated orally with Eimeria acervulina (EA) oocysts, and disease susceptibility was evaluated by assessment of fecal oocyst shedding. Humoral and local cellular mediated immunity were assessed by evaluation of antibody and cytokine (interferon-gamma [IFN-gamma] and interleukin-2 [IL-2]) levels in sera and intestinal secretions on a 3-day interval after inoculation. Fecal oocyst shedding was highest (P < 0.05) in A- birds, followed by AP, C-, and CP birds. Feeding the probiotic reduced shed oocysts by 20% in A fed birds and by 26% in C fed birds. Intestinal IFN-gamma was relatively constant in all treatment groups except for A-, where it declined steadily and was lower (P < 0.05) from day 6 on. Serum IFN-gamma levels fluctuated within each treatment and over time were not revealing. Intestinal IL-2 was highest in CP birds at 3 and 9 days postinfection (DPI) and lowest in A- birds at 3, 9, and 12 DPI (P < 0.05); no difference between treatments was found at 6 DPI (P > 0.05). Eimeria-specific intestinal antibody (Ab) level was constant (P > 0.05) in C- birds but increased with time (P < 0.05) in A-, AP, and CP birds. Serum Ab levels were also constant in A- and CP birds but increased (P < 0.05) in C- and AP birds after 6 DPI. The data demonstrate for the first time a probiotic-enhanced immunity in vitamin A deficient birds. This study is also the first to demonstrate the probiotic effect on local cell-mediated immunity of chickens, best manifested by apparent lower intestinal invasion and development by EA, on the basis of higher IL-2 secretion and lower EA oocyst production.     

<Emphasis Type="Italic">Streptococcus uberis</Emphasis>-specific T cells are present in mammary gland secretions of cows and can be activated to kill <Emphasis Type="Italic">S. uberis</Emphasis>

The presence, phenotype and function of Streptococcus uberis-specific T cells in the mammary gland secretion (MGS) and blood of cows exposed to S. uberis were assessed. MGS T cells in the udder were purified and incubated with autologous blood monocytes as antigen-presenting cells (APC). Most cows, irrespective of prior S. uberis infection status and lactation status, were shown to have S. uberis-specific T cells both in MGS and in the blood. When cells from a subgroup of cows were studied, it was found that the S. uberis-specific T cells produced high levels of interferon-gamma (IFN-γ), but low levels of interleukin-10 (IL-10). A high percentage of responding T cells were of the CD8 ⁺ memory (CD45RO) subset. T cells from the MGS specific for S. uberis were propagated from animals during the drying off period and expanded in vitro using interleukin-2 (IL-2) and S. uberis antigens. This led to the accumulation of T cells of the CD8 ⁺ subset bearing memory cell markers (CD45A ⁻ , CD45RO ⁺ ), which released high levels of IFN-γ. Four of the five T cell lines derived from the MGS of three animals had substantial direct killing activity towards S. uberis in vitro. It is concluded that there is an emergence of S. uberis-specific bactericidal T cells in the MGS of cows after infection or environmental exposure to S. uberis. Vaccines aimed at activating and expanding this T cell population in the mammary glands of cattle may offer an avenue for the prevention of mastitis caused by S. uberis.