Pengaruh Pemberian Kalsium Terhadap Pertumbuhan Plasmodium Falciparum in Vitro

Peningkatan permeabilitas sel eritrosit yang terinfeksi Plasmodium falciparum terhadap ion dan makromolekul diketahui sebagai mekanisme parasit untuk memenuhi nutrisi dalam proses pertumbuhan. Peningkatan permeabilitas terhadap kalsium masih merupakan hal yang kontradiktif dalam peranannya meningkatkan pertumbuhan Plasmodium falciparum dalam sel eritrosit. Tujuan dari penelitian ini adalah mengetahui peningkatan pertumbuhan Plasmodium falciparum dalam sel eritrosit pasca pemberian kalsium. Biakan primer Plasmodium falciparum dalam medium biakan RPMI 1640 yang menghasilkan parasitemia 15%, dilakukan inokulasi untuk pembuatan subkultur yang menghasilkan parasitemia 2% dan dilakukan pembagian untuk kelompok perlakuan pemberian kalsium dan kontrol (ML 10%) dengan replikasi 3 kali. Pengamatan dilakukan hari pertama sampai hari ke-6 setelah perlakuan. Pengamatan pertumbuhan dilakukan dengan parameter parasitemia, bentuk skizon, hemolisis dan kalsium intraseluler. Hasil penelitian menunjukkan bahwa pemberian kalsium menghasilkan peningkatan tertinggi jumlah total rerata parasitemia (11,09 ± 4,01) (Rerata ± SD), bentuk skizon (23,52 ± 10,83), hemolisis (0,278 ± 0,03) dan kalsium intraseluler (6,55 ± 1,88), dibandingkan dengan media biakan kontrol (ML 10%). Analisis T-test (α= 0,05) menghasilkan perbedaan yang signifikan pada parameter parasitemia, bentuk skizon, hemolisis tetapi tidak memberikan perberbedaan yang signifikan pada parameter kalsium intraseluler

Climatic controls on peatland black spruce growth in relation to water table variation and precipitation

Prior research has demonstrated the importance of water limitations and increasing temperatures on upland black spruce (Picea mariana [Mill.] B.S.P.) tree growth, which is a dominant component of the North American boreal forest. However, little work has been done to investigate the connectivity between growth and hydro‐climate in peatland black spruce systems. The boreal forest is the largest global terrestrial biome and is highly threatened due to current and projected increases in temperatures for the northern latitudes. Here we explore the dynamics among annual black spruce growth, climate, and water table elevations using 45 years of in situ precipitation, temperature, and water table elevation coupled with dendrochronological analysis from six research peatlands at the Marcell Experimental Forest, MN, USA. From 1963 to 2010, we found weak relationships between water table elevation and black spruce growth at the six study sites. Instead, annual black spruce growth was most favourable during three climatic periods: (a) cool, moist conditions in mid‐summer; (b) warm mid‐spring temperatures; and (c) cool temperatures in the fall prior to the current growing season. The disconnect between black spruce growth and water table dynamics was surprising and suggests that either annual black spruce growth is minimally responsive to hydrological fluctuations at the timescale we analysed or there is great elasticity of black spruce growth to peatland water table and evapotranspiration dynamics under the range of hydrological fluctuations contained in our record

Long-term impacts of forest treatments on water yield: a summary for northeastern USA

Abstract Long-term changes in annual water yield are summarized and compared for 11 catchment studies in the northeastern USA. Substantial increases in water yield of up to 350mm year -I were obtained in the first year by clearing forest vegetation and controlling regrowth with herbicides. Commercial clearcutting with natural regrowth resulted in initial increases in water yield of 110 250 mm year I. This range in response was due to differences in precipitation and configuration of cuttings. Unless regrowth was controlled with herbicides, yield increases declined quickly after cutting, seldom persisting for more than 10 years. However, yield increases were readily extended over 20 years or more with intermediate cuttings and/or repeated control of regrowth with herbicides. Nearly all increases in water yield occur during the growing season as augmentation of baseflow. Changes in species composition after forest cutting on several study catchments eventually resulted in decreased water yields compared with those from uncut, control catchments. Results are discussed in terms of implications for surface water supplies, global climate change, nutrient cycling, hydrological modeling, and long-term research