DNA polymerase beta is the major dRP lyase involved in repair of oxidative base lesions in DNA by mammalian cell extracts.

The repair of oxidative base lesions in DNA is a coordinated chain of reactions that includes removal of the damaged base, incision of the phosphodiester backbone at the abasic sugar residue, incorporation of an undamaged nucleotide and sealing of the DNA strand break. Although removal of a damaged base in mammalian cells is initiated primarily by a damage-specific DNA glycosylase, several lyases and DNA polymerases may contribute to the later stages of repair. DNA polymerase beta (Pol beta) was implicated recently as the major polymerase involved in repair of oxidative base lesions; however, the identity of the lyase participating in the repair of oxidative lesions is unclear. We studied the mechanism by which mammalian cell extracts process DNA substrates containing a single 8-oxoguanine or 5,6-dihydrouracil at a defined position. We find that, when repair synthesis proceeds through a Pol beta-dependent single nucleotide replacement mechanism, the 5'-deoxyribosephosphate lyase activity of Pol beta is essential for repair of both lesions.     

Effects of the timing of applications on the incompatibility of three fungicides and one isolate of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Deuteromycotina)

Abstract: The effect of timing of application on the incompatibility of three fungicides (metalaxyl, mancozeb, copper oxide) and isolate MK2001 of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin was assessed in vitro . Isolate MK 2001 at 1 × 10⁷ conidia/ml concentration was highly pathogenous to adults of Lygus lineolaris (Hemiptera) (84% mortality at day 4 post-treatment). The fungicides at the manufacturer recommended rate (1X) were strongly fungistatic and inhibited the fungal isolate radial growth on Sabouraud dextrose agar (SDA). Mancozeb, metalaxyl and copper oxide exhibited insecticidal activity of 24, 40 and 48% respectively, on L. lineolaris adults. It is clear that application of the fungal isolate MK2001 2–4 days before applying fungicides metalaxyl, mancozeb or copper oxide synergized the insecticidal effect of the isolate. On the contrary, application of metalaxyl, mancozeb, copper oxide 2–4 days before applying isolate MK2001 antagonized the insecticidal effect. The simultaneous use of each fungicide (metalaxyl, mancozeb or copper oxide) and the isolate gave lesser insect mortality. This study revealed that although some fungicides are incompatible for use alongside fungal isolates, the proper evaluation of their time of use could be beneficial in biological control or IPM programmes. Furthermore, the application of B. bassiana isolate MK2001 followed by fungicide application could synergize insecticidal activity.     

The taxonomic status, distribution and conservation of the lowland anoa Bubalus depressicornis and mountain anoa Bubalus quarlesi

1. The anoas are two species of dwarf buffalo, the lowland anoa Bubalus depressicornis and mountain anoa Bubalus quarlesi that are endemic to the island of Sulawesi, Indonesia. The classification of the subgenus Anoa within Bubalus is upheld by assessment of recent genetic and morphological research. The classification of anoas into two species is still debated, but with the absence of significant opposing evidence, this position is adopted here. 2. Information about the distribution of the two species is presented that adds to but largely supports existing reports. However, it is still uncertain whether the two putative species are sympatric or parapatric in their distribution. A review of anoa distribution from historical reports and recent field data (1990s to 2002) highlights their decline throughout Sulawesi, especially in the southern and north-eastern peninsulas. The decline has been attributed to local hunting for meat and habitat loss. Most populations are rapidly becoming fragmented, suggesting that the conservation of viable populations may eventually require management of metapopulations. 3. There is an urgent requirement for conservation efforts to: (i) protect anoas from hunting; (ii) prevent habitat loss in key sites; (iii) complete genetic studies to better determine the number of anoa taxa and Management Units and assess their distribution; and (iv) determine the status of the remaining anoa populations.     

Gastroduodenal ulceration following active immunization with prostaglandin E2 in dogs. Role of gastric acid secretion

In this study we present evidence to suggest that gastroduodenal mucosal defects may occur in gastric fistula dogs actively immunized with PGE2-thyroglobulin conjugate. One of four PGE2-immunized dogs developed a chronic pyloroduodenal ulcer with penetration into the pancreas and the other three had endoscopic evidence of gastric and/or duodenal erosions. In contrast, no gastroduodenal mucosal defects were seen in control dogs immunized with thyroglobulin alone. Occurrence of gastroduodenal ulcers or erosions was temporally related to formation of specific antibody to PGE2 suggesting that PGE2 antibody may be responsible for lesion formation. An increase in gastric acid secretion was not observed in PGE2-immunized dogs. Thus, it is likely that mucosal defects occur as a result of an impairment of PGE2-mediated mucosal defense mechanisms. Since gastroduodenal lesions can be visualized by endoscopy, the dog may prove to be useful in studying the role of endogenous PG in ulcer diseases.