Biologically active substances from higher plants: Status and future potential

Plant breeding and selection, husbandry techniques and crop protection technology, including agrochemicals, have all made substantial contributions to the present-day level of crop productivity. However, yield losses due to disease, pests and weeds must continue to be minimized in order to meet the food supply demands from an ever growing population. Appropriate synthetic chemicals are becoming increasingly difficult to discover and develop due to stricter requirements on efficacy, selectivity, toxicology and general environmental impact. Consequently, there is a growing interest in understanding and utilising natural mechanisms as the basis for crop protection products. Plants themselves are a rich source of biologically active substances which could potentially be harnessed to modify crop growth or to protect crops against disease and pests. This review describes briefly the current status of understanding relative to plant–plant (herbicide and plant growth substances), plant–fungal (fungicide) and plant–insect (insecticide) interactions. Future prospects are considered in relation to directed synthesis, cell culture, microbial pesticides and plant genetic engineering. The opinion expressed is optimistic and suggests that science today can be utilised to secure the food supply of tomorrow. However, utilising either natural products or molecular biology may require an improved understanding of crop physiology and new developments in agronomy. Therefore, the time-frame for major impact of the ‘new’ technologies on crop productivity may be longer than is commonly predicted.     

Electroacupuncture at the Zusanli and Baihui acupoints ameliorates type-2 diabetes-induced reductions in proliferating cells and differentiated neuroblasts in the hippocampal dentate gyrus with increasing brain-derived neurotrophic factor levels

In the current study, we investigated whether electroacupuncture (EA) can inhibit pathological reductions in neurogenesis. Zucker diabetic fatty (ZDF) rats at 7 weeks of age were anesthetized with zoletil, and sham-acupuncture or EA at the Zusanli (ST36) and Baihui (GV20) acupoints was administered once a day for 5 weeks. In the ZDF group that received sham-EA (ZDF-Sham group), the blood glucose level was significantly increased together with age as compared to the control littermates [Zucker lean control (ZLC) rat]. In contrast, proliferating cells and differentiated neuroblasts were significantly decreased in the ZDF-Sham group compared to the ZLC group. Although EA treatment decreased blood glucose levels, this was not statistically significant when compared to blood glucose levels changes in the ZDF-Sham group. However, proliferating cells and differentiated neuroblasts were significantly increased with EA in ZDF rats as compared to those in the ZDF-Sham group. Brain-derived neurotrophic factor (BDNF) levels were significantly decreased in hippocampal homogenates of ZDF-Sham group compared to those in the ZLC group. The EA treatment significantly increased the BDNF levels compared to those in the ZDF-Sham group, and BDNF levels in this group were similar to those in the ZLC group. These results suggest that EA at ST36 and GV20 can ameliorate the reductions in proliferating cells and differentiated neuroblasts in the dentate gyrus induced by type-2 diabetes without significantly reducing blood glucose levels with increasing BDNF levels.     

Biochemical indices of vascular function, glucose metabolism and oxidative stress in horses with equine Cushing's disease

REASONS FOR PERFORMING STUDY: The mechanisms underlying the increased risk of laminitis in horses with equine Cushing's disease (ECD) are poorly understood. HYPOTHESIS: That abnormalities in glucose homeostasis, similar to those which cause microvascular dysfunction in human diabetics, contribute to development of laminitis in horses with ECD. METHODS: Thirty-one aged horses were divided into 3 groups based on clinical signs and dexamethasone suppression testing (DST). Group 1 (n = 12) had clinical ECD as evidenced by hirsutism. Group 2 (n = 10) had a positive DST but no hirsutism. Group 3 (n = 9) were controls without ECD, with a negative DST and no clinical evidence of ECD. Biochemical indices of glucose metabolism, vascular function and oxidative stress were determined in single morning blood samples. RESULTS: Group 1 had abnormalities in glucose homeostasis, including increased levels of glucose and insulin, compared to Groups 2 and 3. Groups 1 and 2 had significantly lower plasma thiol (PSH) levels and nonsignificantly lower albumin-corrected PSH levels than Group 3, consistent with oxidative stress. CONCLUSIONS AND POTENTIAL RELEVANCE: The observed abnormalities in glucose metabolism and oxidative stress could potentially contribute to development of laminitis in horses with ECD, by similar mechanisms to those that cause microvascular dysfunction in human diabetics. The absence of inter-group differences in the biochemical indices of vascular function precludes their use as preclinical diagnostic indicators of vascular dysfunction. The study also highlighted limitations in the premortem diagnosis of ECD.     

Field Investigation of Perinatal Mortality in Friesian Cattle Associated with Myocardial Degeneration and Necrosis

Perinatal mortality and stillbirths were investigated in an extensively managed herd of Friesian cows and heifers calving over a 2‐year period: 504 cows were calved and 215 heifers. Cows were bred to Friesian and Jersey bulls using natural service. The perinatal fetal mortality rate was 7.5% for cows and 30% for heifers. An experienced stockman managed these calvings and veterinary assistance was required only on nine occasions. All stillborn fetuses were examined post‐mortem by the Veterinary Laboratories Agency, Carmarthen and no infectious agent was identified on any occasion. Thyroid hyperplasia was found in two fetuses. In blood samples taken from 10 late pregnant heifers, mean glutathione peroxidase values were 7.9 ± 1.7 IU/ml Packed Cell Volume (PCV). Tissues from eight fetuses were submitted to the University of Liverpool for histopathological examination; all presented lesions consistent with myocardial degeneration and necrosis of the left ventricle. Following treatment of 205 late pregnant heifers with sodium selenite and vitamin E, the overall perinatal mortality rate in these cattle fell to below 11%.     

Investigation of bovine haemoplasmas and their association with anaemia in New Zealand cattle

CASE HISTORY AND CLINICAL FINDINGS: A dairy cow, from a herd in the Waikato region of New Zealand, was reported with regenerative anaemia on 12 September 2014. Testing of blood from the animal using PCR assays for Theileria orientalis produced a negative result for both Chitose and Ikeda types.

LABORATORY FINDINGS: Using PCR and DNA sequencing, blood from the cow was positive for Candidatus Mycoplasma haemobos. Further testing of another 12 animals from the case herd, 27 days after the affected cow was first reported, showed 11 animals were positive for Candidatus M. haemobos or Mycoplasma wenyonii in the PCR. None of these cattle were clinically anaemic or positive for T. orientalis Ikeda type using PCR.

A convenience sample of 47 blood samples from cattle throughout New Zealand, submitted to the Investigation and Diagnostic Centre (Ministry for Primary Industries) for surveillance testing for T. orientalis Ikeda, was selected for further testing for bovine haemoplasmas. Of these samples, 6/47 (13%) and 13/47(28%) were positive for M. wenyonii and Candidatus M. haemobos, respectively. There was no difference in the proportion of samples positive for the bovine haemaplasmas between cattle with anaemia that were negative for T. orientalis (6/20, 33%), or without anaemia or T. orientalis (10/18, 56%), or from cattle herds experiencing anaemia and infection with T. orientalis Ikeda type (3/9, 33%).

DIAGNOSIS: Bovine haemoplasmosis.

CLINICAL RELEVANCE: The presence of bovine haemoplasmas in blood does not establish causality for anaemia in cattle. Diagnosis of anaemia associated with haemoplasmosis would require exclusion of other causes of regenerative anaemia and an association of the agent with anaemia in affected cattle herds. The data collected in this study did not provide evidence that bovine haemoplasmas were associated with a large number of outbreaks of anaemia in cattle in New Zealand.     

The first reported outbreak of equine herpesvirus myeloencephalopathy in New Zealand

CASE HISTORY AND CLINICAL FINDINGS: On 9 January 2014 (Day 0) a mare from a stud farm in the Waikato region presented with urinary incontinence without pyrexia. Over the following 33 days 15 mares were clinically affected with neurological signs. All but one mare had a foal at foot. The most commonly observed clinical signs were hind limb paresis and ataxia. In some cases recumbency occurred very early in the course of disease and seven mares were subject to euthanasia for humane reasons.

LABORATORY FINDINGS: Equid herpesvirus (EHV) type 1 was detected using PCR in various tissues collected post mortem from two mares with neurological signs. DNA sequencing data from the DNA polymerase gene of the virus showed a nucleotide transition at position 2254, a mutation encoding amino acid D₇₅₂ that is highly associated with the neuropathogenic genotype of EHV-1. In total 12/15 mares were confirmed positive for EHV-1 on PCR. Results from a virus neutralisation test and ELISA on paired serum samples, and PCR on whole blood and nasal swabs, indicated that of four paddocks in a high-risk area where a cluster of cases had occurred, 20/21 (95%) horses were likely to have been exposed or were confirmed infected with EHV-1. Subsequent to the outbreak two mares aborted, one at 9 months and one at 10 months of gestation. The cause of abortion was confirmed as EHV-1 with the same genotype as that involved in the outbreak.

DIAGNOSIS: Equine herpesvirus myeloencephalopathy.

CLINICAL RELEVANCE: The outbreak described shows the considerable impact that can occur in outbreaks of equine herpesvirus myeloencephalopathy in New Zealand. Early biosecurity controls not only reduced the effect on the farm but mitigated the potential for the virus to spread to other horse enterprises.     

Factors Impacting Ethanol Production from Grain Sorghum in the Dry-Grind Process

The goal of this research is to understand the key factors affecting ethanol production from grain sorghum. Seventy genotypes and elite hybrids with a range of chemical compositions and physical properties selected from ≈1,200 sorghum lines were evaluated for ethanol production and were used to study the relationships of composition, grain structure, and physical features that affect ethanol yield and fermentation efficiency. Variations of 22% in ethanol yield and 9% in fermentation efficiency were observed among the 70 sorghum samples. Genotypes with high and low conversion efficiencies were associated with attributes that may be manipulated to improve fermentation efficiency. Major characteristics of the elite sorghum genotypes for ethanol production by the dry-grind method include high starch content, rapid liquefaction, low viscosity during liquefaction, high fermentation speed, and high fermentation efficiency. Major factors adversely affecting the bioconversion process are tannin content, low protein digestibility, high mash viscosity, and an elevated concentration of amylose-lipid complex in the mash.     

Evaluation of Different Extraction Methods for the Assessment of Heavy Metal Bioavailability in Various Soils

The main objective of this study was to compare the effectiveness of different methods (heavy metals in pore water (PW), diffusive gradients in thin films (DGT), diethylene triamine pentaacetic acid (DTPA) extraction, and total heavy metals (THM) in soil) for the assessment of heavy metal bioavailability from soils having various properties and heavy metal contents. The effect of soil heavy metal pollution on shoot yield and sulfatase enzyme activity was also studied. Wheat (Triticum aestivum) was grown in different soils from Spain (n?=?10) and New Zealand (n?=?20) in a constant environment room for 25 days. The bioavailabilities of Cd, Cr, Cu, Ni, Pb, and Zn were assessed by comparing the metal contents extracted by the different methods with those found in the roots. The most widely applicable method was DGT, as satisfactory Cu, Ni, Pb, and Zn root concentrations were obtained, and it was able to distinguish between low and high Cr values. The analysis of the metal concentrations in PW was effective for the determination of Cr, Ni, and Zn content in root. Copper and Pb root concentrations were satisfactorily assessed by DTPA extraction, but the method was less successful with determining the Ni and Cr contents and suitable just to distinguish between high and low concentrations of Zn. The THM in soil method satisfactorily predicted Cu and Pb root concentrations but could only be used to distinguish between low and high Cr and Zn values. The Cd root concentration was not successfully predicted for any of the used methods. Neither shoot yield nor sulfatase enzyme activity was affected by the metal concentrations.