Pemetaan akuifer dengan teknik geoelektrik di Sungai Kelambu, Banting, Selangor

Pengukuran keberintangan secara menegak dan secara 2D telah dilakukan di Sungai Kelambu, Banting untuk memetakan lapisan dan jenis air yang terdapat dalam akuifer pasir serta endapan yang berada di sekitarnya. Pengukuran keberintangan menegak dilakukan di sebanyak 29 stesen manakala pengukuran keberintangan 2D dilakukan di sebanyak 8 profil. Keberintangan sebenar yang diperolehi menerusi permodelan songsang telah dikorelasikan dengan data lubang gerudi yang berhampiran untuk memudahkan pentafsiran. Berdasarkan pentafsiran, lapisan lempung didapati berkerintangan 8-180m dan tebal purata 15m berada di atas lapisan akuifer pasir berkeberintangan 40-800m dan tebal 35-87m. Lapisan pasir ini terendap di atas metasedimen yang berjulat keberintangan 600-800 m. Selain daripada fakta keberintangan dan ketebalan, taburan stesen kajian telah memungkinkan pembinaan peta kontur untuk melihat taburan ketebalan dan keberintangan lapisan akuifer. Peta kontur ketebalan menunjukkan bahagian akuifer yang paling tebal terletak di bahagian tengah dan tenggara kawasan kajian. Oleh sebab julat keberintangan akuifer ini berkisar di antara 40-800m, ini bermakna akuifer tersebut mengandungi air segar hingga payau

Identification of Genomewide Alternative Splicing Events in Sequential, Isogenic Clinical Isolates of Candida albicans Reveals a Novel Mechanism of Drug Resistance and Tolerance to Cellular Stresses

ABSTRACT Alternative splicing (AS)—a process by which a single gene gives rise to different protein isoforms in eukaryotes—has been implicated in many basic cellular processes, but little is known about its role in drug resistance and fungal pathogenesis. The most common human fungal pathogen, Candida albicans, has introns in 4 to 6% of its genes, the functions of which remain largely unknown. Here, we report AS regulating drug resistance in C. albicans. Comparative RNA-sequencing of two different sets of sequential, isogenic azole-sensitive and -resistant isolates of C. albicans revealed differential expression of splice isoforms of 14 genes. One of these was the superoxide dismutase gene SOD3, which contains a single intron. The sod3Δ/Δ mutant was susceptible to the antifungals amphotericin B (AMB) and menadione (MND). While AMB susceptibility was rescued by overexpression of both the spliced and unspliced SOD3 isoforms, only the spliced isoform could overcome MND susceptibility, demonstrating the functional relevance of this splicing in developing drug resistance. Furthermore, unlike AMB, MND inhibits SOD3 splicing and acts as a splicing inhibitor. Consistent with these observations, MND exposure resulted in increased levels of unspliced SOD3 isoform that are unable to scavenge reactive oxygen species (ROS), resulting in increased drug susceptibility. Collectively, these observations suggest that AS is a novel mechanism for stress adaptation and overcoming drug susceptibility in C. albicans. IMPORTANCE The emergence of resistance in Candida albicans, an opportunistic pathogen, against the commonly used antifungals is becoming a major obstacle in its treatment. The necessity to identify new drug targets demands fundamental insights into the mechanisms used by this organism to develop drug resistance. C. albicans has introns in 4 to 6% of its genes, the functions of which remain largely unknown. Using the RNA-sequencing data from isogenic pairs of azole-sensitive and -resistant isolates of C. albicans, here, we show how C. albicans uses modulations in mRNA splicing to overcome antifungal drug stress