Responses of triacylglycerol synthesis inSkeletonema marinoito nitrogen and phosphate starvations(1)
JOURNAL OF PHYCOLOGY
Authors: Zhang, Mei; Xing, Yongze; Wang, Fuwen; Mi, Tiezhu; Zhen, Yu
Abstract
Skeletonema marinoiis one of the most widespread marine planktonic diatoms in temperate coastal regions and sometimes can form massive blooms. Yet, the molecular mechanisms of triacylglycerol (TAG) synthesis in nutrient-deficient conditions for this species are still unknown. This study aimed to investigate how the TAG biosynthetic pathway ofS. marinoireacts to the culture age and nitrogen (N) or phosphorus (P) deficiency at molecular levels. Meanwhile, we also described the physiological and biochemical changes ofS. marinoiin response to N or P starvation over time. To obtain reliable qRT-PCR data, six putative reference genes were identified for assessing expression stability using geNorm and BestKeeper software, andActinexhibited the most stable expression across 45 testedS.marinoisamples. We found that the expression of TAG biosynthesis-related genes andACCaseenzyme activity varied in response to the different nutrient conditions and culture age. Taken together, we speculated that the capacity of TAG biosynthesis inS. marinoiis induced by N or P stress, and increases with culture age. Furthermore, TAG biosynthesis appears to respond more strongly to P deficiency than to N deficiency. Our study provides important insights into how diatoms regulate the TAG biosynthetic pathway when stressed by nutrient limitation. Besides, the data obtained from this study also provide useful clues for further exploring genes that can be used for metabolic engineering to enhance lipid production.
Cross-reaction of POC-CCA urine test for detection ofSchistosoma mekongiin Lao PDR: a cross-sectional study
INFECTIOUS DISEASES OF POVERTY
Authors: Homsana, Anousin; Odermatt, Peter; Southisavath, Phonesavanh; Yajima, Aya; Sayasone, Somphou
Abstract
Background The point-of-care circulating cathodic antigen (POC-CCA) test is increasingly used as a rapid diagnostic method forSchistosoma mansoniinfection. The test has good sensitivity, although false positive results have been reported among pregnant women and patients with urine infections and hematuria. We validated the POC-CCA test's ability to diagnoseSchistosoma mekongiinfection in Lao People's Democratic Republic (Lao PDR), whereS. mekongiis endemic. Of particular interest was the test's specificity and possible cross-reactivity with other helminth infections. Methods We conducted a cross-sectional study of children and adults in the provinces of Champasack (Schistosoma mekongiandOpisthorchis viverriniendemic), Savannakhet (O. viverriniendemic) and Luang Prabang (soil-transmitted helminths endemic) between October 2018 and April 2019.POC-CCA and urine dipstick tests were administered to all study participants, while an additional pregnancy test was offered to women. Two stool samples were collected from participants and examined with a Kato-Katz test (two smears per stool). Logistic regression was used to associate potential confounding factors (predictors) with POC-CCA test results (outcome). Results InS. mekongi-endemic Champasack, 11.5% (n = 366) and 0.5% (n = 2) of study participants had positive POC-CCA and Kato-Katz test results, respectively. Only one of the two Kato-Katz positive patients was also POC-CCA positive. In Champasack and Luang Prabang, whereS. mekongiis not endemic, the POC-CCA test yielded (presumably) false positive results for 6.0% (n = 22) and 2.5% (n = 9) of study participants, respectively, while all of the Kato-Katz tests were negative. POC-CCA positive test results were significantly associated withO. viverriniinfection (1.69, 95% confidence interval (CI): 1.02-2.77,P = 0.042), increased leukocytes (adjusted Odds Ratio(aOR) = 1.58, 95%CI: 1.15-2.17,P = 0.005) and hematuria (aOR = 1.50, 95%CI: 1.07-2.10,P = 0.019) if the observed trace was counted as a positive test result. Two pregnant women from Champasack province had POC-CCA positive tests. Conclusions We observed a cross-reaction between the POC-CCA test andO. viverriniinfection. To some extent, we can confirm previous observations asserting that POC-CCA provides false positive results among patients with urinary tract infections and hematuria. InS. mekongi-endemic areas, POC-CCA can be applied cautiously for surveillance purposes, keeping in mind the considerable risk of false positive results and its unknown sensitivity.