Blossom-end rot is associated with impairment of sugar metabolism and growth of pepper (Capsicum annuum L.) fruits

Summary

Blossom-end rot (BER) in pepper fruits is known as a “physiological” disease which is evoked by climatic and osmotic stresses (e.g., high temperatures and salinity) and by deficit irrigation management. The physiological and biochemical mechanisms involved in the stimulation of BER are still a matter of dispute. It has been proposed that BER occurs under cultivation conditions that accelerate fruit growth beyond calcium supply to the growing tissue. In the present study, we investigated this hypothesis by recording fruit growth and sugar metabolism under normal and BER-inducing conditions.The results showed that pepper fruits grown in a ventilated-cooled greenhouse, which ameliorated BER, had a higher initial growth rate than those grown in a non-cooled greenhouse, but had lower calcium concentrations in the fruit pericarp. Fruits that grew without ventilation-cooling had higher concentrations of apoplastic and symplastic sucrose and reducing sugars, and higher levels of symplastic starch than those that developed in a cooled greenhouse. Concomitantly, fruits that developed in a non-cooled greenhouse had lower acid invertase, sucrose synthase and fructokinase activities than those that developed in a cooled greenhouse. Accordingly, the non-necrotic part of BER-affected fruits had higher concentrations of symplastic starch, reducing sugars and sucrose than healthy fruits. These findings indicate that the occurrence of BER in pepper fruits was associated with impaired sucrose metabolism in fruit tissues, which led to reductions in growth rate and final size. Thus, the present findings negate the notion that BER occurs when fruit growth rate is stimulated, and favour the idea that direct impairment of fruit sugar metabolism and of normal fruit growth are involved.     

Molecular identification, genetic diversity and distribution of Theileria and Babesia species infecting small ruminants

Detection and identification of Theileria and Babesia species in 920 apparently healthy small ruminants in eastern Turkey, as well as parasite genetic diversity, was investigated using a specifically designed reverse line blot (RLB) assay. The hypervariable V4 region of the 18S ribosomal RNA (rRNA) gene was amplified and hybridized to a membrane onto which catchall and species-specific oligonucleotide probes were covalently linked. Three Theileria and one Babesia genotype were identified. Comparison of the Theileria genotypes revealed 93.6-96.2% similarity among their 18S rRNA genes. Two Theileria shared 100% and 99.7% similarity with the previously described sequences of T. ovis and Theileria sp. OT3, respectively. A third Theileria genotype was found to be clearly different from previously described Theileria species. The genotype was provisionally designated as Theileria sp. MK. The Babesia genotype shared 100% similarity with Babesia ovis. The survey indicated a high prevalence of piroplasm infections in small ruminants (38.36%). Theileria spp. prevalence was 36.08%. Prevalence of B. ovis was 5.43%. The most abundant Theileria species identified was T. ovis (34.56%) followed by Theileia sp. MK (1.30%) and Theileria sp. OT3 (0.43%).     

Effects of chloride and partial substitution of reduced forms of nitrogen for nitrate in nutrient solution on the nitrate,total nitrogen,and chloride contents of onion

An experiment was conducted to determine the effects of chloride (Cl) and reduced forms of nitrogen (N) on the nitrate (NO₃), total N, and Cl concentrations in onion (Allium cepa L.) plants using a non‐recirculating nutrient film growing system. The reference treatment was a nutrient solution containing 19 mM NO₃ and 1.25 mM ammonium (NH₄). The results from this treatment were compared with that obtained using mixed amino acid, urea, and glycine treatments with or without additional Cl (10 mM) in which 20% of the NO₃ in the reference treatment was substituted with one of these reduced forms of N. Fresh and dry weights of the onion plants were not affected by the treatments. The NO₃ content was considerably lower in the mixed amino acid treatment, being 4236 mg NO₃/kg FW as compared to either the reference, urea, or glycine treatments. The NO₃ contents of the plants in these treatments were 5393, 5339, and 5261 mg NO₃/kg FW, respectively. The presence of Cl in the nutrient solution also reduced the NO₃ content of the plants from 5816 to 4299 mg NO₃/kg FW. The reduced‐N treatments increased the total N contents of the plants. The Cl content of the plants was increased by the Cl supplied and by the reduced forms of N in the nutrient solution.     

In vivo quantification of muscle damage in dogs after general anaesthesia with halothane andpropofol

Muscle damage in dogs anaesthetised with halothane and propofol was quantified by measurement of the area under the curve of plasma creatine kinase (CK) versus time. Plasma CK remained unchanged during anaesthesia for two and a half and five hours. Following halothane anaesthesia of dogs (resting on one side directly on the surgical table or on cushions, and with or without rotation of the body every 30 minutes), plasma CK was elevated in some animals to 10 000 U/litre by the 12th hour (baseline value ≤100 u/litre), whereas it remained almost unchanged in other animals. Plasma CK then returned to reference values on day 2 or 3. The mean equivalent of muscle damaged ranged from 0–6 to 0–9 g/kg bodyweight. No muscle damage could be demonstrated in animals anaesthetised with propofol. It is therefore concluded that plasma CK should not be used as a diagnostic aid following halothane anaesthesia because of false positives due to the halothane anaesthesia itself and that propofol Is best suited for the investigation of muscle damage due to surgical procedures.