Naturally occurring and experimental Stachys arvensis (staggerweed) toxicity in lambs in New Zealand

Stachys arvensis (staggerweed) is a common, widely distributed weed of cultivated and waste land with the potential to intoxicate sheep. Two naturally occurring outbreaks of suspected staggerweed toxicity in the lower North Island were investigated. Affected lambs had been recently moved onto staggerweed-contaminated Brassica spp. crops. In total, 150/1,200 (13%) lambs developed hindlimb paresis, a fine generalised muscular tremor, and hunched posture. When forced to move, many became recumbent. Most lambs recovered within 48 h of removal from staggerweed, although a few developed clinical signs again when transported 2–3 weeks later. Grossly, affected lambs had large amounts of staggerweed plant material and seeds within the rumen. Histopathology showed mild, multifocal degeneration of the white matter tracts of the central nervous system (CNS), most commonly in the ventral funiculi of the spinal cord, and acute, mild to moderate, multifocal degeneration of skeletal muscles. Creatine kinase (CK) activity in serum was mildly to markedly elevated in affected lambs. In a feeding trial, ten 10-month-old Romney lambs were randomly assigned to equal treatment and control groups. Treated lambs were drenched with a liquid extract of staggerweed once daily for 7 days. Three of five treated lambs developed mild exercise intolerance, and 1/5 displayed mild paresis of the hindlimbs, slightly crouched hindlimb stance, and shortened gait, on days 6 and 7. Histologically, 4/5 treated lambs had degeneration in white matter tracts of the CNS, indistinguishable from those seen in the lambs in the outbreak, and in 1/5 lambs there was scattered regeneration of skeletal muscle. CK activity in serum in treated lambs was not significantly higher than that in control lambs. None of the control lambs developed significant clinical signs, histological changes or increases in CK activity in serum. The clinical signs and lesions observed in both the outbreaks and feeding trial were similar to those previously described in studies in Australia, with the exception that myodegeneration was more prominent in the outbreaks in New Zealand. Further characterisation of the pathogenesis of staggerweed toxicity and its potential role as a food safety hazard will be facilitated through identification of the toxic principle(s).     

Effect of NaCl on growth and ion relations in two salt-tolerant strains of Paxillus involutus

The effect of NaCl on growth, biomass and ion relations of two salt-tolerant isolates of Paxillus involutus, MAJ and NAU were investigated. The two Paxillus strains were exposed to the following concentrations of NaCl： 0, 100, 200 and 500 mmol·L^-1. Growth of MAJ and NAU was enhanced by 100 mmol·L^-1 NaCl but severely inhibited at the concentration of 500 mmol·L^-1. NAU exhibited a greater capacity to exclude Na^＋ and Cl^- under all salinity levels, whereas the salt-includer MAJ had a higher capacity in nutrient uptake under salt stress. The ratios Na^＋/K^＋, Na^＋/Ca^2＋ and Na^＋/Mg^2＋ in NaCl-treated MAJ and NAU did not increase at levels of 100 and 200 mmol·L^-1 NaCl but markedly increased at 500 mmol·L^-1. This suggests that the two strains, especially MAJ, enhanced nutrient uptake corresponding to the increased Na^＋ influx at moderate salinity. We conclude that both MAJ and NAU are able to tolerate 500 mmol·L^-1 NaCl but there are species-specific differences in retaining ionic homeostasis in the two Paxillus strains. NAU is a salt-excluder, MAJ is a salt-includer but retains a high capacity in nutrient selectivity under saline conditions. Their definite mechanisms to enhance salt tolerance of mycorrhizal hosts need further study.     

Colostrum yield and litter performance in multiparous sows subjected to farrowing induction

The consumption of colostrum at a low level can compromise the survival and growth of piglets. Therefore, this study aimed to evaluate the effect of farrowing induction on colostrum yield, IgG concentration and the survival and performance of piglets until the weaning. Sows of parity 3 to 7 were assigned into two groups: Control (n = 48), sows with spontaneous farrowing; and induction (n = 48), sows induced to farrow on day 114 of gestation with a PGF₂ analogue. Colostrum and blood samples were collected from the sows, at farrowing and 24 hr later. Blood samples from the piglets were collected at 24 hr after birth. The performance of the piglets was evaluated in a subsample of 28 litters from each group. All piglets were weighed at 7, 14 and 20 days of age. The farrowing length, the number of piglets born alive, stillborn piglets, weight at birth, litter weight at birth and colostrum yield were not significantly affected (p > .05) by farrowing induction. There was no difference between the groups (p > .05) in the percentage of sows with obstetric interventions. Serum IgG concentration, in both sows and piglets, and colostrum IgG concentration were similar between the groups (p > .05). Furthermore, survival rate, piglet weight and litter weight at 7, 14 and 20 days of age were also similar between the groups (p > .05). Therefore, it can be concluded that the farrowing induction performed on day 114 of gestation does not affect the colostrum yield, the IgG concentration in colostrum and serum of piglets, and the litter performance until the weaning.     

Endometrial gene expression in primiparous dairy cows at the end of the voluntary waiting period is affected by nutrition: Total mixed ration vs increasing levels of herbage allowance

The study postulated that differential nutritional management during the early lactation period would be reflected in endometrial expression of genes related to embryo growth at the end of the voluntary waiting period. Thus, the effect of the combined use of total mixed ration (TMR) and grazing under different herbage allowances during the first 75 days post‐partum (DPP) on endometrial gene expression was evaluated in primiparous dairy cows. Cows were blocked by body weight, age and body condition score and randomly assigned to three grazing treatments: high (HA, 30 kg DM per cow per day), medium (MA, 15 kg DM per cow per day) and low (LA, 7.5 kg DM per cow per day) herbage allowance (mixed pasture, 2,600 kg DM per ha) plus 8 kg DM of supplement or TMR (55% forage, 45% concentrate) fed ad libitum (TMR) from calving to 75 DPP. At 57 DPP, cows were synchronized for oestrus (day 0, 68 DPP) and at day 7, endometrial biopsies were obtained. The nutritional treatment did not affect insulin, IGF‐1 and leptin concentrations on days 0, 4 or 7. Expression of IGF1, IGFBP3, IGFBP4, ADIPOR1 and ADIPOR2 mRNA was significantly affected by the nutritional treatment. Endometrial IGF1 and IGFBP4 mRNA were twofold greater in TMR and HA than MA and LA cows. Expression of IGFBP3 and ADIPOR1 mRNAs was greater in TMR and HA than MA cows, but did not differ from LA cows. All groups had greater expression of ADIPOR2 mRNA than MA cows. This study provided solid evidence of the importance of nutritional management during early lactation on uterine environment at the end of the voluntary waiting period. The greater expression of genes related to embryo growth and uterine function (IGF system, progesterone and adiponectin receptors) in cows fed diets maximizing energy intake suggests a favourable environment for embryonic growth, which may explain the improved reproductive performance of cows in good energy balance.     

Exhaustive Screening of Long-Term Pollutants in Riverbank Sediments of the Wurm River,Germany

Fluvial sediments can act as archives for long-term pollution. However, in environmental studies, often only preselected contaminants and, therefore, only a limited part of the pollution are considered. Herein, geochemical investigations of riverbank samples of the Wurm River (catchment <?400 km²) depict the anthropogenic impact of the city Aachen (250,000 inhabitants) to its main outlet resulting in an exhaustive list of present pollutants including their concentrations. The study is based on 14 riverbank sediment samples at eight sampling sites on a 7.6-km-long segment of the Wurm River. The sediment samples were analyzed for grain size composition (laser diffraction particle size analyzer), total organic carbon (TOC), trace element inventory (X-ray fluorescence), and organic compounds (chromatography-mass spectrometry). Here, we report quantitative data for 71 persistent organic substances as well as six trace elements (Cu, Zn, As, Ba, Hg, and Pb) entering the Wurm River due to domestic and industrial emissions. In general, a slight decline of, e.g., PTEs, DDX, and PCB concentrations with decreasing sampling depth points to a steady improvement of conditions. Whereas no clear trends can be seen for organic pollutants along the investigated reach with increasing distance to the main source of pollution (Aachen city). As obtained concentrations for organic pollutants indicate a rather low level of pollution, trace element values exceed geogenic background values by far. Furthermore, we used selected compounds as time markers for a rough estimation of sedimentation rates. Obtained values point to a highly complex morphodynamic regime with changing sedimentation rates (0.6 to 3.0 cm a^?1) within barely 100 m of river course.     

Sensitivity of boreal forest carbon balance to soil thaw

We used eddy covariance; gas-exchange chambers; radiocarbon analysis; wood, moss, and soil inventories; and laboratory incubations to measure the carbon balance of a 120-year-old black spruce forest in Manitoba, Canada. The site lost 0.3 +/- 0.5 metric ton of carbon per hectare per year (ton C ha-1 year-1) from 1994 to 1997, with a gain of 0.6 +/- 0.2 ton C ha-1 year-1 in moss and wood offset by a loss of 0.8 +/- 0.5 ton C ha-1 year-1 from the soil. The soil remained frozen most of the year, and the decomposition of organic matter in the soil increased 10-fold upon thawing. The stability of the soil carbon pool ( approximately 150 tons C ha-1) appears sensitive to the depth and duration of thaw, and climatic changes that promote thaw are likely to cause a net efflux of carbon dioxide from the site.     

Gas-phase ionic reactions: dynamics and mechanism of nucleophilic displacements

Nucleophilic displacement reactions (the SN2 reaction) of ions in the gas phase are a prototypical reaction system that allows a study of dynamics, mechanisms, and structure-energy relations. This article reviews aspects of the kinetics (especially the applicability of statistical reaction rate theory), the relation of structure and reactivity, and the effects of small numbers of solvent molecules on the reaction and compares the behavior of the ionic reaction in the gas phase with that in solution.