An egg‐laying device to estimate the induction of sterility in Ceratitis capitata (Diptera: Tephritidae) sterile insect technique programmes

Area‐wide environmentally friendly pest control methods such as the sterile insect technique (SIT) are being developed and improved to contribute in managing agricultural, environmental and public health problems. A key aspect to evaluate performance of sterile males is to directly measure sterility induction in the field. Sterility induction has been estimated for tephritid fruit flies by recovering egg from host fruit in the field, the method is, however, impractical, and past efforts to develop artificial egg‐laying devices have not prospered. Here, we evaluated response of wild gravid Ceratitis capitata (Medfly) females to long‐distance fruit‐based chemical attractants, visual and tactile stimuli to develop an artificial egg‐laying device. The device combining the most attractive features was further tested under two deployment schemes. Finally, devices and deployment tactics were used to compare fertility levels between feral Medfly females under conventional management and under SIT. Agar spheres wrapped in plastic film, baited with pressed peach juice and visually enhanced with yellow discs received more egg than other combinations of attractive features. Such devices also received more eggs when deployed on fruitless trees and when placed on the orchard perimeter. The egg hatch in an orchard under conventional management was estimated at 86%, whilst egg hatch in an area under SIT was reduced to 31%. The egg‐laying devices are therefore useful to measure sterility induction and can be further improved by refining long‐distance attraction and deployment schemes.     

Evaluation of total reactive antioxidant potential (TRAP) of tissue homogenates and their cytosols

This study evaluates the possibility of obtaining total reactive antioxidant potential (TRAP) indexes in homogenates and their cytosolic fractions by a procedure based on the quenching of luminol luminescence induced by the thermolysis of 2,2'-azo-bis(2-amidinopropane). Measurements were performed in rat brain, liver, kidney, and heart homogenates. TRAP indexes can be easily determined both in homogenates and their cytosolic fractions. The results obtained indicate that heart homogenates are the least and liver homogenates the most protected of the systems considered. Glutathione is the measured antioxidant that contributes the most to TRAP values, while uric acid makes a significant contribution only in liver. A calculation of theoretical TRAP values from the measured concentrations of the main antioxidants (glutathione, uric acid, ascorbic acid, and alpha-tocopherol) for the different homogenates shows that, in most tissues (liver, brain, and kidney), nearly 50% of the experimentally determined TRAP values are not accounted for. This difference is mainly due to the contribution of proteins to the measured TRAP.     

Myocardial remodeling after discrete radiofrequency injury: effects of tissue inhibitor of matrix metalloproteinase-1 gene deletion

Discrete myocardial lesions created through the delivery of radiofrequency (RF) energy can expand; however, the mechanisms have not been established. Matrix metalloproteinases (MMPs) play an important role in myocardial remodeling, and MMP activity can be regulated by the tissue inhibitors of the metalloproteinases (TIMPs). This study examined the role of TIMP-1 in postinjury myocardial remodeling. Lesions were created on the left ventricular (LV) epicardium of wild-type (WT, 8-12 wk, 129SVE) and age-matched TIMP-1 gene-deficient (timp-1(-/-)) mice through the delivery of RF current (80 degrees C, 30 s). Heart mass, LV scar volumes, and collagen content were measured at 1 h and 3, 7, and 28 days postinjury (n = 10 each). Age-matched, nonablated mice were used as reference controls (n = 5). Heart mass indexed to tibial length increased in WT and timp-1(-/-) mice but was greater in the timp-1(-/-) mice by 7 days. Scar volumes increased in a time-dependent manner in both groups but were higher in the timp-1(-/-) mice than the WT mice at 7 days (1.48 +/- 0.09 vs. 1.20 +/- 0.11 mm(3).mg(-1).mm, P < 0.05) and remained higher at 28 days. In the remote myocardium, wall thickness was greater and relative collagen content was lower in the timp-1(-/-) mice at 28 days postinjury. Discrete myocardial RF lesions expand in a time-dependent manner associated with myocyte hypertrophy remote to the scar. Moreover, postinjury myocardial remodeling was more extensive with TIMP-1 gene deletion. Thus TIMP-1 either directly or through modulation of MMP activity may regulate myocardial remodeling following infliction of a discrete injury.     

Mutagenesis of human DNA polymerase lambda: essential roles of Tyr505 and Phe506 for both DNA polymerase and terminal transferase activities

DNA polymerase (pol) λ is homologous to pol β and has intrinsic polymerase and terminal transferase activities. However, nothing is known about the amino acid residues involved in these activites. In order to precisely define the nucleotide-binding site of human pol λ, we have mutagenised two amino acids, Tyr505 and the neighbouring Phe506, which were predicted by structural homology modelling to correspond to the Tyr271 and Phe272 residues of pol β, which are involved in nucleotide binding. Our analysis demonstrated that pol λ Phe506Arg/Gly mutants possess very low polymerase and terminal transferase activities as well as greatly reduced abilities for processive DNA synthesis and for carrying on translesion synthesis past an abasic site. The Tyr505Ala mutant, on the other hand, showed an altered nucleotide binding selectivity to perform the terminal transferase activity. Our results suggest the existence of a common nucleotide-binding site for the polymerase and terminal transferase activities of pol λ, as well as distinct roles of the amino acids Tyr505 and Phe506 in these two catalytic functions.     

Differential ability of genotypes of 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens strains to colonize the roots of pea plants

Indigenous populations of 2,4-diacetylphloroglucinol (2,4-DAPG)-producing fluorescent Pseudomonas spp. that occur naturally in suppressive soils are an enormous resource for improving biological control of plant diseases. Over 300 isolates of 2,4-DAPG-producing fluorescent Pseudomonas spp. were isolated from the rhizosphere of pea plants grown in soils that had undergone pea or wheat monoculture and were suppressive to Fusarium wilt or take-all, respectively. Representatives of seven genotypes, A, D, E, L, O, P, and Q, were isolated from both soils and identified by whole-cell repetitive sequence-based PCR (rep-PCR) with the BOXA1R primer, increasing by three (O, P, and Q) the number of genotypes identified previously among a worldwide collection of 2,4-DAPG producers. Fourteen isolates representing eight different genotypes were tested for their ability to colonize the rhizosphere of pea plants. Population densities of strains belonging to genotypes D and P were significantly greater than the densities of other genotypes and remained above log 6.0 CFU (g of root)(-1) over the entire 15-week experiment. Genetic profiles generated by rep-PCR or restriction fragment length polymorphism analysis of the 2,4-DAPG biosynthetic gene phlD were predictive of the rhizosphere competence of the introduced 2,4-DAPG-producing strains.