Showing papers by "Shigeyuki Kawano published in 2022"

A CLAVATA3-like Gene Acts as a Gynoecium Suppression Function in White Campion

Abstract: Abstract How do separate sexes originate and evolve? Plants provide many opportunities to address this question as they have diverse mating systems and separate sexes (dioecy) that evolved many times independently. The classic “two-factor” model for evolution of separate sexes proposes that males and females can evolve from hermaphrodites via the spread of male and female sterility mutations that turn hermaphrodites into females and males, respectively. This widely accepted model was inspired by early genetic work in dioecious white campion (Silene latifolia) that revealed the presence of two sex-determining factors on the Y-chromosome, though the actual genes remained unknown. Here, we report identification and functional analysis of the putative sex-determining gene in S. latifolia, corresponding to the gynoecium suppression factor (GSF). We demonstrate that GSF likely corresponds to a Y-linked CLV3-like gene that is specifically expressed in early male flower buds and encodes the protein that suppresses gynoecium development in S. latifolia. Interestingly, GSFY has a dysfunctional X-linked homolog (GSFX) and their synonymous divergence (dS = 17.9%) is consistent with the age of sex chromosomes in this species. We propose that female development in S. latifolia is controlled via the WUSCHEL-CLAVATA feedback loop, with the X-linked WUSCHEL-like and Y-linked CLV3-like genes, respectively. Evolution of dioecy in the S. latifolia ancestor likely involved inclusion of ancestral GSFY into the nonrecombining region on the nascent Y-chromosome and GSFX loss of function, which resulted in disbalance of the WUSCHEL-CLAVATA feedback loop between the sexes and ensured gynoecium suppression in males.

Gamete dimorphism of the isogamous green alga (Chlamydomonas reinhardtii), is regulated by the mating type-determining gene, MID

Abstract: The gametes of chlorophytes differ morphologically even in isogamy and are divided into two types (α and β) based on the mating type- or sex-specific asymmetric positioning of the mating structure (cell fusion apparatus) with respect to the flagellar beat plane and eyespot, irrespective of the difference in gamete size. However, the relationship between this morphological trait and the mating type or sex determination system is unclear. Using mating type-reversed strains of the isogamous alga Chlamydomonas reinhardtii, produced by deletion or introduction of the mating type-determining gene MID, we revealed that the positioning of the mating structure is associated with conversion of mating types (mt- and mt+), implying that this trait is regulated by MID. Moreover, the dominant mating type is associated with the type β phenotype, as in the chlorophyte species Ulva prolifera. Our findings may provide a genetic basis for mating type- or sex-specific asymmetric positioning of the chlorophyte mating structure.

Mimicking platelet indices in patients with malaria and dengue hemorrhagic fever: characteristics and clinical applications

Abstract: Abstract Background Although platelet indices are routinely available using automated blood cell counters, the clinical applications of these parameters for malaria and dengue hemorrhagic fever (DHF) have not been substantially implemented. We conducted this study to investigate the potential role of platelet indices as a prognostic marker in adult patients with Plasmodium vivax malaria, Plasmodium falciparum malaria, and DHF admitted to the Hospital for Tropical Diseases, Bangkok, Thailand. Methods We enrolled 219 eligible patients, comprising 96 with P. falciparum malaria, 71 with P. vivax malaria, and 52 with DHF. We evaluated the study groups’ baseline clinical features and alterations of platelet indices during the first 4 days of admission. Results Upon admission, the initial laboratory findings showed no statistically significant difference in platelet count (PC), plateletcrit (PCT), or platelet distribution width (PDW) between patients with P. vivax and P. falciparum ; however, mean platelet volume (MPV) was significantly higher in patients with P. falciparum . Comparisons of the initial platelet indices in malaria and DHF showed that only PC and PCT were significantly lower in DHF. Although MPV in DHF tended to be lower than in malaria, a statistically significant difference was observed only with P. falciparum . Moreover, the results also showed no significant alterations in the platelet indices among the study groups during the first 4 days of admission. Conclusions and recommendations Clinical presentations of DHF and malaria are nonspecific and may overlap with other common tropical diseases. Alterations of initial platelet indices may be investigated in P. vivax and P. falciparum malaria mimicking DHF. Although a significant reduction in PC and PCT in DHF might be a clue for differential diagnosis of malaria, the use of MPV and PDW might be impractical. We suggest that appropriate laboratory diagnoses for malaria and dengue infections are still needed for the differential diagnosis of acute febrile patients who have a risk of malaria or dengue infections. To clarify the clinical utility of platelet indices in patients with dengue and malaria, further studies are required that particularly include patients with different severities, geographical areas, and levels of health care settings.

Detection of Schistosoma mekongi DNA in Human Stool and Intermediate Host Snail Neotricula aperta via Loop-Mediated Isothermal Amplification Assay in Lao PDR

Abstract: Schistosomiasis mekongi infection represents a public health concern in Laos and Cambodia. While both countries have made significant progress in disease control over the past few decades, eradication has not yet been achieved. Recently, several studies reported the application of loop-mediated isothermal amplification (LAMP) for detecting Schistosoma DNA in low-transmission settings. The objective of this study was to develop a LAMP assay for Schistosoma mekongi using a simple DNA extraction method. In particular, we evaluated the utility of the LAMP assay for detecting S. mekongi DNA in human stool and snail samples in endemic areas in Laos. We then used the LAMP assay results to develop a risk map for monitoring schistosomiasis mekongi and preventing epidemics. A total of 272 stool samples were collected from villagers on Khon Island in the southern part of Laos in 2016. DNA for LAMP assays was extracted via the hot-alkaline method. Following the Kato-Katz method, we determined that 0.4% (1/272) of the stool samples were positive for S. mekongi eggs, as opposed to 2.9% (8/272) for S. mekongi DNA based on the LAMP assays. Snail samples (n = 11,762) were annually collected along the riverside of Khon Island from 2016 to 2018. DNA was extracted from pooled snails as per the hot-alkaline method. The LAMP assay indicated that the prevalence of S. mekongi in snails was 0.26% in 2016, 0.08% in 2017, and less than 0.03% in 2018. Based on the LAMP assay results, a risk map for schistosomiasis with kernel density estimation was created, and the distribution of positive individuals and snails was consistent. In a subsequent survey of residents, schistosomiasis prevalence among villagers with latrines at home was lower than that among villagers without latrines. This is the first study to develop and evaluate a LAMP assay for S. mekongi detection in stools and snails. Our findings indicate that the LAMP assay is an effective method for monitoring pathogen prevalence and creating risk maps for schistosomiasis.

Glucose-6-phosphate Dehydrogenase (G6PD) A-Variant Frequency and Novel Polymorphism in Haiti

Abstract: ABSTRACT. There are scarce data about the glucose-6-phosphate dehydrogenase (G6PD) variants in Haiti to guide public health guidelines. In this study, we investigated the prevalence of the G6PD mutations related to the A- variant. We found an allelic frequency of 35.8% for the A376G mutation and of 12.2% for the G202A mutation. We also found a novel C370T mutation concomitant with the A376G mutation in one study participant. The G680T and T968C mutations were not found. The G6PD deficient variant A202 (A376G and G202A mutations) has appreciable prevalence in Haiti (16.6%), consideration is warranted when using drugs such as primaquine, which may trigger hemolytic anemia among G6PD-deficient people.

Clinical performance testing of the automated haematology analyzer XN-31 prototype using whole blood samples from patients with imported malaria in Japan

Abstract: Abstract Background The automated haematology analyzer XN-31 prototype (XN-31p) is a new flow cytometry-based device developed to measure the number and the ratio of malaria-infected red blood cells (MI-RBC) with a complete blood count (CBC). The XN-31p can provide results in about one minute and also can simultaneously provide information on the malaria parasite ( Plasmodium ) species. In this study, clinical testing of the XN-31p was performed using blood samples from patients with imported malaria in Japan. Methods Blood samples were collected from 80 patients who visited the hospital of the National Center for Global Health and Medicine, Tokyo, Japan, for malaria diagnosis from January 2017 to January 2019. The test results by the XN-31p were compared with those by other standard methods, such as microscopic observation, rapid diagnostic tests and the nested PCR. Results Thirty-three patients were diagnosed by the nested PCR as being malaria positive (28 Plasmodium falciparum , 2 Plasmodium vivax , 1 Plasmodium knowlesi , 1 mixed infection of P. falciparum and Plasmodium malariae , and 1 mixed infection of P. falciparum and Plasmodium ovale ), and the other 47 were negative. The XN-31p detected 32 patients as “MI-RBC positive”, which almost matched the results by the nested PCR and, in fact, completely matched with the microscopic observations. The ratio of RBCs infected with malaria parasites as determined by the XN-31p showed a high correlation coefficient of more than 0.99 with the parasitaemia counted under microscopic observation. The XN-31p can analyse the size and nucleic acid contents of each cell, and the results were visualized on a two-dimensional cytogram termed the “M scattergram”. Information on species and developmental stages of the parasites could also be predicted from the patterns visualized in the M scattergrams. The XN-31p showed a positive coincidence rate of 0.848 with the nested PCR in discriminating P. falciparum from the other species. Conclusions The XN-31p could rapidly provide instructive information on the ratio of MI-RBC and the infecting Plasmodium species. It was regarded to be of great help for the clinical diagnosis of malaria.

Semi-in vitro detection of Mg2+-dependent DNase that specifically digest mitochondrial nucleoids in the zygote of Physarum polycephalum

Abstract: The maternal/uniparental inheritance of mitochondria is controlled by the selective elimination of paternal/uniparental mitochondria and digestion of their mitochondrial DNA (mtDNA). In isogamy, the selective digestion of mtDNA in uniparental mitochondria is initiated after mating and is completed prior to the elimination of mitochondria, but the molecular mechanism of the digestion of uniparental mtDNA remains unknown. In this study, we developed a semi-in vitro assay for DNase, wherein the digestion of mitochondrial nucleoids (mt-nucleoids) was microscopically observed using isolated mitochondria from Physarum polycephalum and the DNase involved in uniparental inheritance was characterized. When myxamoebae of AI35 and DP246 are crossed, mtDNA and mt-nucleoid from only the DP246 parent are digested. The digestion of mt-nucleoids was observed in zygotes 3 h after plating for mating. During the digestion of mt-nucleoids, mitochondrial membrane integrity was maintained. In the semi-in vitro assay, the digestion of mt-nucleoids was only observed in the presence of Mg2+ at pH 7.5-9.0. Moreover, such Mg2+-dependent DNase activity was specifically detected in mitochondria isolated from zygotes 3 h after plating for mating. Therefore, Mg2+-dependent DNase is potentially involved in uniparental inheritance. Our findings provide insights into the DNase involved in uniparental inheritance and its regulatory mechanism.

Clinical performance testing of the automated haematology analyzer XN-31 prototype using whole blood samples from patients with imported malaria in Japan

Abstract: Abstract Background The automated haematology analyzer XN-31 prototype (XN-31p) is a new flow cytometry-based device developed to measure the number and the ratio of malaria-infected red blood cells (MI-RBC) with a complete blood count (CBC). The XN-31p can provide results in about one minute and also can simultaneously provide information on the malaria parasite ( Plasmodium ) species. In this study, clinical testing of the XN-31p was performed using blood samples from patients with imported malaria in Japan. Methods Blood samples were collected from 80 patients who visited the hospital of the National Center for Global Health and Medicine, Tokyo, Japan, for malaria diagnosis from January 2017 to January 2019. The test results by the XN-31p were compared with those by other standard methods, such as microscopic observation, rapid diagnostic tests and the nested PCR. Results Thirty-three patients were diagnosed by the nested PCR as being malaria positive (28 Plasmodium falciparum , 2 Plasmodium vivax , 1 Plasmodium knowlesi , 1 mixed infection of P. falciparum and Plasmodium malariae , and 1 mixed infection of P. falciparum and Plasmodium ovale ), and the other 47 were negative. The XN-31p detected 32 patients as “MI-RBC positive”, which almost matched the results by the nested PCR and, in fact, completely matched with the microscopic observations. The ratio of RBCs infected with malaria parasites as determined by the XN-31p showed a high correlation coefficient of more than 0.99 with the parasitaemia counted under microscopic observation. The XN-31p can analyse the size and nucleic acid contents of each cell, and the results were visualized on a two-dimensional cytogram termed the “M scattergram”. Information on species and developmental stages of the parasites could also be predicted from the patterns visualized in the M scattergrams. The XN-31p showed a positive coincidence rate of 0.848 with the nested PCR in discriminating P. falciparum from the other species. Conclusions The XN-31p could rapidly provide instructive information on the ratio of MI-RBC and the infecting Plasmodium species. It was regarded to be of great help for the clinical diagnosis of malaria.

False-positive fourth-generation HIV test result in a woman with Plasmodium malariae malaria.

Abstract: BACKGROUND False positive results on fourth-generation human immunodeficiency virus (HIV) diagnostic tests have previously been reported in infections with Plasmodium falciparum and Plasmodium ovale but not with Plasmodium malariae. METHODS We report a false positive fourth-generation HIV test result in a patient with P. malariae infection. The patient's symptoms improved rapidly with antimalarial treatment and the confirmatory and repeated HIV tests were eventually negative. RESULTS False positive results may add a variety of unnecessary burden. CONCLUSIONS One must be aware of false positive results even with fourth-generation tests in patients with malaria, including P. malariae malaria.