Effects of resin harvesting on the status of the Agathis philippinensis population in the Cleopatra's Needle Critical Habitat, the Philippines

In Palawan, the Philippines, a biological hotspot was turned into a protected area, called Cleopatra’s Needle Critical Habitat (CNCH). The most important goals of the CNCH are to conserve the rich endemic biodiversity and to maintain the culture of the Batak, a group of indigenous people who depend on forest resources for their livelihood. As resin extraction from Agathis philippinensis is a key component of the income of the Batak people, it is important to study the scope for sustainable exploitation of this species. This study focused on the effects of resin harvesting on the physical status and mortality of A. philippinensis trees in 15 subpopulations within the CNCH. These population characteristics were related to the intensity of resin harvest and the distance to communities. We found that the physical tree status deteriorated and the proportion of dead trees increased with harvest intensity and proximity to communities. These results indicate that overharvesting of the resource is taking place, which may lead to prolonged recruitment failure and population decline of A. philippinensisin the study area

DNA repair mechanisms involved in gemcitabine cytotoxicity and in the interaction between gemcitabine and cisplatin

The influence of DNA repair mechanisms on the interaction between gemcitabine and cisplatin was studied using a panel of Chinese hamster ovary (CHO) cell lines each deficient in one of the following repair pathways: base excision repair (BER), nucleotide excision repair (NER), homologous recombination (HR) and non-homologous end joining (NHEJ). NER and HR are known to be involved in platinum-DNA adduct repair. Single agent experiments demonstrated that each of the repair deficient cell lines had a similar sensitivity towards gemcitabine as the parental cell lines, whereas the NER- and HR-deficient lines showed increased sensitivity towards cisplatin. Furthermore, in the parental cell lines, the administration sequence cisplatin followed by gemcitabine was synergistic, whereas the reversed schedule showed additivity and simultaneous administration revealed antagonistic cytotoxicity. In the repair deficient cell lines, using this synergistic schedule of cisplatin followed by gemcitabine, loss of synergy was observed in the NER- and HR-deficient cell lines. However, the magnitude of the effect in the NER-deficient cells was small. The sensitivity to the combination of cisplatin and gemcitabine shown by the BER- and NHEJ-deficient cell lines did not differ significantly from that of the parental cell line. Cellular accumulation of platinum as well as the formation of GG- and AG-intrastrand adducts in the parental line and in the HR-deficient line were not affected by gemcitabine. In conclusion, our results indicate that BER, NER, HR, and NHEJ are most likely incapable of modulating the cytotoxicity of gemcitabine, and that HR is involved in the synergistic interaction between cisplatin and gemcitabine in our cell system