Assessment of crop damage by rodent pests from experimental barley crop fields in Farta District, South Gondar, Ethiopia

Formulation and evaluation of solid lipid nanoparticles loaded with papaya seed chloroform extract for long-term antifertility effects on the male rat, Bandicota bengalensis

The study is the first to formulate and investigate potential of papaya seed chloroform extract based solid lipid nanoparticles (PSCEN) as antifertility agents on male Bandicota bengalensis. The prepared nanoparticles were spherical of size 300-600 nm. The release kinetics showed a controlled release of the drug with major release over 48 h. To assess the antifertility effects of PSCEN, adult male rats were fed a diet containing two different concentrations of PSCEN (5% and 10%) for 15 days under bi-choice conditions. The mean total active ingredient ingestion of the rats in the two treated groups ranged from 2.13-3.31 and 3.92-5.87 g/100g body weight, respectively. No adverse effects of treatment on body weight were observed. Also, no mortality of rats was observed. The treatment had a significant effect on the weight of the testis and the epididymis, but not on the other organs. Sperm motility (%), sperm viability (%), sperm count (millions/ml), sperm mitochondrial activity (%), sperm nuclear chromatin de-condensation (%) and sperm hypo-osmotic swelling (%) were significantly decreased, and sperm abnormality (%) significantly increased compared to the vehicle control group. The reproductive success rates of male rats treated with 5% and 10% PSCEN and mated with untreated female rats were 20.00-66.67% and 16.67%, respectively, while in untreated female rats mated with male rats of vehicle control group, reproductive success rate was 33.33 to 80%. The study found a maximal antifertility effect of the 10% PSCEN containing bait, which was irreversible up to 105 days after stopping treatment, suggesting long-term efficacy.

Immunogenicity and contraceptive efficacy of plant-produced putative mouse-specific contraceptive peptides

Rodent population control through contraception requires species-specific oral contraceptive vaccines. Therefore, in this study, we produced putative mouse-specific contraceptive peptides, mZP2 (from oocyte) and mIzumo1 (from sperm), in plants using Agrobacterium-mediated transient expression. Peptides were produced separately in Nicotiana benthamiana using constructs encoding antigens containing three copies of each peptide. We also determined the immunogenicity and contraceptive effects of the plant-produced antigens in female BALB/c mice. Mice immunized subcutaneously with a relatively low amount of antigen (5 µg/dose of each peptide in a mixture) showed systemic immune responses against mZP2-3 and mIzumo1-3 antigens. Moreover, the mean litter size of mice treated with the plant-produced antigens was reduced by 39% compared to that of the control mice. Notably, there was a significant negative correlation between the number of pups born and individual antibody levels against both antigens. Immunofluorescence assays demonstrated the binding of induced antibodies to the oocytes of BALB/c and wild-type mice in vivo and in vitro, respectively. Our study demonstrate the feasibility of producing small contraceptive peptides in plants that can be further used to develop oral contraceptive vaccines against mouse populations.

Natural Products-Based Botanical Bactericides Discovery: Novel Abietic Acid Derivatives as Anti-Virulence Agents for Plant Disease Management

The discovery of natural product-based pesticides is critical for agriculture. In this work, a series of novel tricyclic diterpenoid derivatives decorated with an amino alcohol moiety were elaborately prepared from natural abietic acid, and their antibacterial behavior was explored. Bioassay results indicated that compound C₂ exhibited the most promising bioactivity (EC₅₀ = 0.555 μg mL^-1) against Xanthomonas oryzae pv. oryzae (Xoo), about 73 times higher than the effect of commercial thiodiazole copper (TC). Results of in vivo bioassays showed that compound C₂ displayed significantly higher control of rice bacterial leaf blight (curative activity: 63.8%; protective activity: 58.4%) than TC (curative activity: 43.6%; protective activity: 40.8%), and their bioactivity could be improved maximally 16% by supplementing the auxiliaries. Antibacterial behavior suggested that compound C₂ could suppress various virulence factors. Overall, these findings suggested that new botanical bactericide candidates could control intractable plant bacterial diseases by suppressing virulence factors.

Oral and Subcutaneous Immunization with a Plant-Produced Mouse-Specific Zona Pellucida 3 Peptide Presented on Hepatitis B Core Antigen Virus-like Particles

A short mouse-specific peptide from zona pellucida 3 (mZP3, amino acids 328-342) has been shown to be associated with antibody-mediated contraception. In this study, we investigated the production of mZP3 in the plant, as an orally applicable host, and examined the immunogenicity of this small peptide in the BALB/c mouse model. The mZP3 peptide was inserted into the major immunodominant region of the hepatitis B core antigen and was produced in Nicotiana benthamiana plants via Agrobacterium-mediated transient expression. Soluble HBcAg-mZP3 accumulated at levels up to 2.63 mg/g leaf dry weight (LDW) containing ~172 µg/mg LDW mZP3 peptide. Sucrose gradient analysis and electron microscopy indicated the assembly of the HBcAg-mZP3 virus-like particles (VLPs) in the soluble protein fraction. Subcutaneously administered mZP3 peptide displayed on HBcAg VLPs was immunogenic in BALB/c mice at a relatively low dosage (5.5 µg mZP3 per dose) and led to the generation of mZP3-specific antibodies that bound to the native zona pellucida of wild mice. Oral delivery of dried leaves expressing HBcAg-mZP3 also elicited mZP3-specific serum IgG and mucosal IgA that cross-reacted with the zona pellucida of wild mice. According to these results, it is worthwhile to investigate the efficiency of plants producing HBcAg-mZP3 VLPs as immunogenic edible baits in reducing the fertility of wild mice through inducing antibodies that cross-react to the zona pellucida.

Indigenous agricultural knowledge: A neglected human based resource for sustainable crop protection and production

Indigenous knowledge, developed over generations and owned by communities or individuals within a community, offers alternative strategies and perspectives on resource management and use. However, as emphasized in the contemporary agricultural history of Ethiopia, the most effective indigenous agricultural knowledge has not been well documented and some of them are replaced by modern techniques. This study was therefore conducted to assess and document community-based techniques to control pests and diseases and the practical implications of indigenous farming techniques. A focus group discussion, key informant interviews and semi-structured questionnaires were conducted with 150 farmers. The result showed that a substantial number (92%) of the farming community uses indigenous based plant protection measures. Indigenous farmers (92%) splash liquids made of cow urine to control the adverse effect of fungi. Farmers are also using different seed selection methods for next season planting. About 29% of the farmers do single head-based seed selection prior to mass harvesting, 34% are collected as "Qerm" and 45% select their seeds during threshing. Indigenous farming knowledge varies with the natural feature of the growing location and cropping system, including the rainfall pattern, soil fertility status, crop, and weed type. The observed positive effect of indigenous agricultural practices on crop production substantiates the need to include these essential approaches in the cultivation system along with the modern agronomic techniques. This might reduce the dependency on expensive and pollutant agricultural inputs. However, sociodemographic factors such as educational level, marital status and farming experience have been found as a determinant factor that influences utilization of indigenous farming knowledge. It can be therefore inferred that documenting indigenous knowledge and proving its applicability scientifically could contribute to organically oriented agricultural production and consequently reduce agriculture's contribution to environmental pollution.

Plant-Produced Mouse-Specific Zona Pellucida 3 Peptide Induces Immune Responses in Mice

Contraceptive vaccines are designed to stimulate autoimmune responses to molecules involved in the reproductive process. A mouse-specific peptide from zona pellucida 3 (mZP3) has been proposed as a target epitope. Here, we employed a plant expression system for the production of glycosylated mZP3 and evaluated the immunogenicity of plant-produced mZP3-based antigens in a female BALB/c mouse model. In the mZP3-1 antigen, mZP3 fused with a T-cell epitope of tetanus toxoid, a histidine tag, and a SEKDEL sequence. A fusion antigen (GFP-mZP3-1) and a polypeptide antigen containing three repeats of mZP3 (mZP3-3) were also examined. Glycosylation of mZP3 should be achieved by targeting proteins to the endoplasmic reticulum. Agrobacterium-mediated transient expression of antigens resulted in successful production of mZP3 in Nicotiana benthamiana. Compared with mZP3-1, GFP-mZP3-1 and mZP3-3 increased the production of the mZP3 peptide by more than 20 and 25 times, respectively. The glycosylation of the proteins was indicated by their size and their binding to a carbohydrate-binding protein. Both plant-produced GFP-mZP3-1 and mZP3-3 antigens were immunogenic in mice; however, mZP3-3 generated significantly higher levels of serum antibodies against mZP3. Induced antibodies recognized native zona pellucida of wild mouse, and specific binding of antibodies to the oocytes was observed in immunohistochemical studies. Therefore, these preliminary results indicated that the plants can be an efficient system for the production of immunogenic mZP3 peptide, which may affect the fertility of wild mice.