The Exploitation of Nematode-Responsive Plant Genes in Novel Nematode Control Methods

The molecular interactions between plants and sedentary nematodes are undergoing intense study, not only for reasons of fundamental research but also for the potential benefits to agriculture. The present technology allows the transformation of an increasing number of crop plants, providing new ways to introduce resistance against plant-parasitic nematodes. The ability of sedentary nematodes to induce specialized feeding sites in plant roots is one of the most fascinating aspects of this host–parasite interaction. Molecular approaches have been initiated to identify and characterize plant genes altered in expression after infection by sedentary nematodes. The results obtained indicate that many genes indeed become up-regulated upon nematode infection. Surprisingly, several so-called constitutive promoters that are normally used to achieve high expression in plant cells are completely ‘silenced’ in the feeding sites within days after nematode infection. Generally, there are two options available for the genetic engineering of nematode resistance: the synthesis of anti-nematode proteins or the localized production of a cytotoxic protein that interferes with the development of feeding cells. Nematode-induced promoters are very useful for the production by plants of sufficiently high levels of anti-nematode proteins at feeding sites. Alternatively, interfering with feeding-cell development is somewhat similar to the hypersensitive response evoked by nematodes in a naturally resistant plant. Here, destruction of specific plant cells can be achieved by the localized expression of a cytotoxin such as barnase, a potent ribonuclease. This approach, however, calls for a highly specific ‘non-leaky’ promoter, which is active only in the feeding cells. Another possibility is to use a two-component system, where the leakiness of the promoter in other tissues is counterbalanced by the constitutive expression of a neutralizing gene.     

East Coast fever immunisation field trial in crossbred dairy cattle in Hanang and Handeni districts in northern Tanzania

East Coast fever (ECF) causes considerable mortality and production losses in the Tanzania smallholder dairy sector and limits the introduction of improved dairy breeds in areas where the disease is present. The infection and treatment method (ITM) was adopted by smallholder dairy farms for ECF immunisation in Hanang and Handeni districts of Tanzania. This study recorded incidence rates for ECF and other tick-borne diseases (TBDs) for ECF-immunised and non-immunised cattle between 1997 and 2000. Approximately 80% of smallholder households from both sites (n?=?167) participated in this longitudinal study, with immunisations carried out at the request of the livestock owners. Efficacy of ITM for preventing ECF cases in these crossbred dairy cattle was estimated at 97.6%, while that for preventing ECF deaths was 97.9%. One percent of the cattle developed clinical ECF as a result of immunisation. Since ECF immunisation permits a reduction in acaricide use, an increase in other TBDs is a potential concern. Sixty-three percent of farmers continued to use the same acaricide after immunisation, with 80% of these reducing the frequency of applications. Overall, 78% of farmers increased the acaricide application interval after immunisation beyond that recommended by the manufacturer, resulting in annual savings in the region of USD 4.77 per animal. No statistical difference was observed between the immunised and non-immunised animals in the incidence of non-ECF TBDs. However, immunised animals that succumbed to these diseases showed fewer case fatalities. ITM would therefore appear to be a suitable method for ECF control in Tanzania's smallholder dairy sector.     

Effect of prenatal stress on subsequent response to mixing stress and a lipopolysaccharide challenge in pigs

Sows subjected to prenatal stress have been found to produce offspring that have altered responses to stress. Our objective was to determine if exposing a sow to stress would alter the response of the offspring to lipopolysaccharide (LPS) at 2 mo of age or their response to mixing stress at 4 mo of age. Sow treatments consisted of intravenous injections of ACTH (1 IU/kg of BW), exposure to rough handling for a 10-min duration (rough), or no treatment (control) once per week from d 42 to 77 of gestation. At 2 mo of age, pigs from each treatment, 1 per litter (n = 21, 17, and 15 for the ACTH, rough, and control treatments, respectively), were challenged with 2 μg of LPS/kg of BW or saline, or served as a noninjected control. Their behavioral response to a human approach test and salivary cortisol were measured. At 4 mo of age, 1 pig from each treatment (n = 14, 14, and 15 for the ACTH, rough, and control treatments, respectively) was taken from its home pen and placed in a pen of unfamiliar pigs. At this time, a punch biopsy wound (6 × 6 mm) was created to measure the ability of the pig to heal the wound. At this same time, each pig received a 1-mL intramuscular injection of 20% ovine red blood cells (oRBC), and then a second injection of oRBC at 21 d postmixing. Blood samples were collected 3 times per week for 2 wk and then once a week for 4 more weeks. Blood samples were analyzed for cortisol, porcine corticosteroid-binding globulin, antibody response to oRBC, and nitric oxide production by macrophages. Behavior was recorded during the first 5 d after mixing. All pigs in the LPS challenge responded with characteristic sickness behavior; however, pigs in the rough treatment showed less sickness behavior than those in the other 2 treatments (P < 0.05). Maternal stress treatment did not affect (P < 0.43) salivary cortisol. Pigs from all treatments responded similarly to mixing stress with regard to cortisol, porcine corticosteroid-binding globulin, antibody titers, nitric oxide production, and hematology measures, and all pigs experienced the same amount of aggression in response to mixing. Without altering peripheral measures of stress responsivity, prenatal stress enhanced the ability of pigs to cope with a simulated immune challenge, which could prove to be an adaptation to challenging environments.     

Signs of generalized anxiety and compulsive disorders in chimpanzees

Fear and anxiety have been studied extensively in humans and other animals. However, far less attention has been focused on the clinical and ethical implications of nonhuman animals’ susceptibility to psychological disorders. Behavioral signs of psychopathology in nonhuman animals, including our closest phylogenetic relatives, are rarely described as clinical syndromes. In this study, we drew on approaches described in child psychiatry, veterinary medicine, and primatology, to identify behavioral clusters in chimpanzees comparable with human anxiety disorders, such as generalized anxiety disorder and obsessive–compulsive disorder.In phase 1 of this study, we accessed published case reports of 20 chimpanzees subjected to maternal separation, social isolation, experimentation, or similar experiences. We tested the inter-rater reliability of the Diagnostic and Statistical Manual of Mental Disorders (fourth edition; DSM-IV) criteria for generalized anxiety disorder and obsessive–compulsive disorder when applied to chimpanzees in these case studies. Additionally, based on the DSM-IV, veterinary approaches, and ethograms, we defined behaviorally anchored alternative criteria, which proved more reliable than the DSM-IV criteria in phase 1. In phase 2, the new behaviorally anchored criteria were applied to chimpanzees living in wild sites in Africa (n = 196) and those with previous histories of experimentation, orphanage, illegal seizure, or violent human conflict (n = 168) living in sanctuaries. In phase 2, 18% of chimpanzees living in sanctuaries met the set of behaviorally anchored criteria for generalized anxiety disorder, compared with 0.5% of those in the wild (P = 0.036), and 19% of chimpanzees in sanctuaries met the set of behaviorally anchored criteria for obsessive–compulsive disorder, compared with 0% of those in the wild (P = 0.071).Chimpanzees display behavioral clusters similar to anxiety disorders described in humans, underscoring the importance of ethical considerations regarding their use in experimentation and other captive settings.     

Early Archaean microorganisms preferred elemental sulfur, not sulfate

Microscopic sulfides with low 34S/32S ratios in marine sulfate deposits from the 3490-million-year old Dresser Formation, Australia, have been interpreted as evidence for the presence of early sulfate-reducing organisms on Earth. We show that these microscopic sulfides have a mass-independently fractionated sulfur isotopic anomaly (Delta33S) that differs from that of their host sulfate (barite). These microscopic sulfides could not have been produced by sulfate-reducing microbes, nor by abiologic processes that involve reduction of sulfate. Instead, we interpret the combined negative delta34S and positive Delta33S signature of these microscopic sulfides as evidence for the early existence of organisms that disproportionate elemental sulfur.     

Social rank of pregnant sows affects their body weight gain and behavior and performance of the offspring

Previous studies on group housing of pregnant sows have mainly focused on reproduction, but we hypothesized that the social rank of pregnant sows housed in groups could also affect birth weight, growth, and behavior of their offspring. Therefore, in the present study, pregnant gilts and sows were housed in 15 different groups (n = 7 to 14 animals per group) from 4 d after AI until 1 wk before the expected farrowing date. All groups were fed by an electronically controlled sow feeding system that registered, on a 24-h basis, the time of first visit, number of feeding and non-feeding visits, and number of times succeeding another sow within 2 s. Only in the first 6 groups (n = 57 animals), agonistic interactions were observed continuously. The percentage of agonistic interactions won was highly correlated (r(s) = 0.90, P < 0.001) with the percentage of displacement success (DS) at the feeding station, which was calculated as: [the number of times succeeding another sow within 2 s/(the number of times succeeded by another sow within 2 s + the number of times succeeding another sow within 2 s)] x 100. This allowed us to classify all sows (n = 166) according to their DS: high-social ranking (HSR) sows had a DS >50% (n = 62) and low-social ranking (LSR) sows a DS <50% (n = 104). Body weights before AI did not differ between HSR and LSR sows, but HSR sows gained more BW during gestation, and lost more BW and back-fat during lactation (P < 0.001). Maternal salivary cortisol concentrations at 2, 7, and 13 wk after AI did not differ between HSR and LSR sows, nor did gestation length, litter size, or percentage of live born piglets. During a novel object (NO) test at 3 wk of age, HSR offspring moved and vocalized more than LSR offspring (P < 0.05). In addition, the latency time to touch the NO was shorter in HSR offspring (P < 0.05), and HSR males spent more time near the NO than LSR males (P < 0.01). At weaning, HSR offspring weighed more than LSR offspring (P < 0.05), and at slaughter HSR offspring had more lean meat than LSR offspring (P < 0.05). Results indicate that the social rank of the sow during gestation affects her own BW gain and loss as well as the growth and behavior of her offspring. Pig breeders that apply group housing for pregnant sows should pay attention to reducing competition around the feeding area, which may reduce aggression among the sows and minimize differences between HSR and LSR sows.     

Self-assembled silica-carbonate structures and detection of ancient microfossils

We have synthesized inorganic micron-sized filaments, whose microstucture consists of silica-coated nanometer-sized carbonate crystals, arranged with strong orientational order. They exhibit noncrystallographic, curved, helical morphologies, reminiscent of biological forms. The filaments are similar to supposed cyanobacterial microfossils from the Precambrian Warrawoona chert formation in Western Australia, reputed to be the oldest terrestrial microfossils. Simple organic hydrocarbons, whose sources may also be abiotic and indeed inorganic, readily condense onto these filaments and subsequently polymerize under gentle heating to yield kerogenous products. Our results demonstrate that abiotic and morphologically complex microstructures that are identical to currently accepted biogenic materials can be synthesized inorganically.     

Evaluation of oral administration of cortisol as a model for prenatal stress in pregnant sows

OBJECTIVE: To design a treatment that increases plasma corticosteroid concentrations to mimic prenatal stress in pregnant sows. ANIMALS: 24 pregnant sows. PROCEDURE: Sows were assigned to 1 of 4 treatment groups; treatment consisted of twice-daily oral administration of a placebo or 20, 60, or 180 mg of hydrocortisone acetate (HCA)/sow from 7 to 11 weeks of gestation. Blood and saliva samples for determination of cortisol concentrations were obtained hourly on treatment days 3 and 25 and twice weekly for the remainder of the treatment period. The WBC, neutrophil, and lymphocyte counts and concentrations of interleukin (IL)-2 and IL-4 were determined on 4 days during treatment. Litter characteristics were recorded. RESULTS: Plasma and salivary cortisol concentrations were significantly increased in sows that received 60 or 180 mg of HCA (0.30 to 0.37 mg/kg and 0.95 to 1.15 mg/kg, respectively), compared with control sows. Except for the second day of treatment, the number of WBCs and the IL-2:IL-4 ratio did not differ among treatment groups. The neutrophil-to-lymphocyte ratio was significantly higher in sows that received 180 mg of HCA. Gestation duration was significantly shorter in sows that received 180 mg of HCA. CONCLUSIONS AND CLINICAL RELEVANCE: Oral administration of 60 mg of HCA is suitable to increase plasma and salivary cortisol concentrations in pregnant sows in a controlled manner to concentrations comparable to concentrations detected after psychologic stressors. This model seems to be suitable to study the effects of increased maternal corticosteroid concentrations on young pig behavior, physiologic variables, and development.     

Adhesion of Salmonella enterica serotype Enteritidis isolates to chicken isthmal glandular secretions

The ability of Salmonella enterica serotype Enteritidis isolates to adhere to immobilized secretions of the isthmus of the laying hen was determined in an ELISA-type assay. One-third of the 56 isolates tested in the logarithmic growth phase, adhered to the isthmal secretions. Using a binding assay of the isolates to thin paraffin sections of the oviduct, we demonstrated that the receptor of the adhesion was localized inside the tubular gland cells of the isthmus. The adhesion to immobilized isthmal secretions as well as to the paraffin sections was blocked by the addition of mannose. A fimD mutant of S. Enteritidis, lacking type 1 fimbriae, did not adhere, confirming that the adhesion was mediated by type 1 fimbriae. Mannosylated glycoproteins were demonstrated in the isthmus glandular cells using confocal laser scanning microscopy by FITC-labelled Lens culinaris lectins. It is hypothesized that the binding of S. Enteritidis to isthmal secretions could play a role in the contamination of eggs through incorporation of the bacteria in the shell membranes.