RESUMO
Viruses play important roles in regulating the abundance and composition of bacterial populations in aquatic ecosystems. The bloom-forming toxic cyanobacterium Microcystis aeruginosa is predicted to interact with diverse cyanoviruses, resulting in Microcystis population diversification. However, current knowledge of the genomes from these viruses and their infection programs is limited to those of Microcystis virus Ma-LMM01. Here, we performed a time series sampling at a small pond in Japan during a Microcystis bloom and then investigated the genomic information and transcriptional dynamics of Microcystis-interacting viruses using metagenomic and metatranscriptomic approaches. We identified 15 viral genomic fragments classified into three groups, groups I (including Ma-LMM01), II (high abundance and transcriptional activity), and III (new lineages). According to the phylogenetic distribution of Microcystis strains possessing spacers against each viral group, the group II-original viruses interacted with all three phylogenetically distinct Microcystis population types (phylotypes), whereas the groups I and III-original viruses interacted with only one or two phylotypes, indicating the cooccurrence of broad- (group II) and narrow (groups I and III)-host-range viruses in the bloom. These viral fragments showed the highest transcriptional levels during daytime regardless of their genomic differences. Interestingly, M. aeruginosa expressed antiviral defense genes in the environment, unlike what was seen with an Ma-LMM01 infection in a previous culture experiment. Given that broad-host-range viruses often induce antiviral responses within alternative hosts, our findings suggest that such antiviral responses might inhibit viral multiplication, mainly that of broad-host-range viruses like those in group II.IMPORTANCE The bloom-forming toxic cyanobacterium Microcystis aeruginosa is thought to have diversified its population through the interactions between host and viruses in antiviral defense systems. However, current knowledge of viral genomes and infection programs is limited to those of Microcystis virus Ma-LMM01, which was a narrow host range in which it can escape from the highly abundant host defense systems. Our metagenomic approaches unveiled the cooccurrence of narrow- and broad-host-range Microcystis viruses, which included fifteen viral genomic fragments from Microcystis blooms that were classified into three groups. Interestingly, Microcystis antiviral defense genes were expressed against viral infection in the environment, unlike what was seen in a culture experiment with Ma-LMM01. Given that viruses with a broad host range often induce antiviral responses within alternative hosts, our findings suggest that antiviral responses inhibit viral reproduction, especially that of broad-range viruses like those in group II. This paper augments our understanding of the interactions between M. aeruginosa and its viruses and fills an important knowledge gap.
Assuntos
Bacteriófagos/isolamento & purificação , Microcystis/virologia , Lagoas/microbiologia , Bacteriófagos/genética , Bacteriófagos/fisiologia , Genoma Viral , Proliferação Nociva de Algas , Especificidade de Hospedeiro , Japão , Lagoas/virologiaRESUMO
Bacteriophages rapidly diversify their genes through co-evolution with their hosts. We hypothesize that gene diversification of phages leads to locality in phages genome. To test this hypothesis, we investigated the genetic diversity and composition of Microcystis cyanophages using 104 sequences of Ma-LMM01-type cyanophages from two geographically distant sampling sites. The intergenetic region between the ribonucleotide reductase genes nrdA and nrdB was used as the genetic marker. This region contains the host-derived auxiliary metabolic genes nblA, an unknown function gene g04, and RNA ligase gene g03. The sequences obtained were conserved in the Ma-LMM01 gene order and contents. Although the genetic diversity of the sequences was high, it varied by gene. The genetic diversity of nblA was the lowest, suggesting that nblA is a highly significant gene that does not allow mutation. In contrast, g03 sequences had many point mutations. RNA ligase is involved in the counter-host's phage defense mechanism, suggesting that phage defense also plays an important role for rapid gene diversification. The maximum parsimony network and phylogenic analysis showed the sequences from the two sampling sites were distinct. These findings suggest Ma-LMM01-type phages rapidly diversify their genomes through co-evolution with hosts in each location and eventually provided locality of their genomes.
Assuntos
Bacteriófagos/genética , Água Doce , Variação Genética , Genoma Viral/genética , Microcystis/virologia , Sequência de Aminoácidos , Dados de Sequência Molecular , Mutação/genética , Filogenia , Alinhamento de SequênciaRESUMO
Viruses influence the abundance of host populations through virus-mediated host cell lysis. Viruses contribute to the generation and maintenance of host diversity, which also results in viral diversity throughout their coevolution. Here, to determine the phage gene diversification throughout the coevolution of host and phage in a natural environment, we investigated the genetic diversity and temporal changes in Microcystis cyanophage populations using a total of 810 sequences of the Ma-LMM01-type cyanophage tail sheath gene (g91) from 2006 to 2011 in a natural pond. The sequences obtained were highly diverse and assigned to 419 different genotypes (GT1 to GT419) clustered at 100% nucleotide sequence similarity. A maximum-parsimony network showed that the genotypes were largely divided into three sequence groups, which were dominated by major genotypes (more than 24 sequences: GT2, GT53, and GT163 in group I; GT25 in group II; and GT1 in group III). These major genotypes coexisted and oscillated throughout the sampling periods, suggesting that the Microcystis-cyanophage coevolution was partly driven by a negative frequency-dependent selection. Meanwhile, the high viral genetic diversity observed was derived from a large number of the variants of each major and moderately frequent genotype (including 7 to 18 sequences: GT7, GT26, GT56, GT149, and GT182 in group I; GT152 in group II) (1 or 2 nucleotide substitutions). The variants almost always co-occurred with their origin genotypes. This manner of variant emergence suggests that increased contact frequency within a host-phage population promotes rapid coevolution in a form of "arms race."
Assuntos
Bacteriófagos/genética , Microcystis/virologia , Proteínas da Cauda Viral/genética , Bacteriófagos/classificação , Variação Genética , Genótipo , Dados de Sequência Molecular , Filogenia , Lagoas/virologia , Microbiologia da ÁguaRESUMO
Viruses play important roles in regulating the abundance, clonal diversity, and composition of their host populations. To assess their impact on the host populations, it is essential to understand the dynamics of virus infections in the natural environment. Cyanophages often carry host-like genes, including photosynthesis genes, which maintain host photosynthesis. This implies a diurnal pattern of cyanophage infection depending on photosynthesis. Here we investigated the infection pattern of Microcystis cyanophage by following the abundances of the Ma-LMM01-type phage tail sheath gene g91 and its transcript in a natural population. The relative g91 mRNA abundance within host cells showed a peak during the daylight hours and was lowest around midnight. The phage g91 DNA copy numbers in host cell fractions, which are predicted to indicate phage replication, increased in the afternoon, followed by an increase in the free-phage fractions. In all fractions, at least 1 of 71 g91 genotypes was observed (in tested host cell, free-phage, and RNA fractions), indicating that the replication cycle of the cyanophage (i.e., injection, transcription, replication, and release of progeny phages) was occurring. Thus, Microcystis cyanophage infection occurs in a diel cycle, which may depend on the light cycle. Additionally, our data show that the abundance of mature cyanophage produced within host cells was 1 to 2 orders of magnitude greater than that of released phages, suggesting that phage production may be higher than previously reported.
Assuntos
Bacteriófagos/crescimento & desenvolvimento , Microcystis/virologia , Microbiologia da Água , DNA Viral/química , DNA Viral/genética , Japão , Dados de Sequência Molecular , Lagoas , Análise de Sequência de DNA , Transcrição Gênica , Proteínas Virais/genéticaRESUMO
BACKGROUND: Making lifestyle changes is an essential element of abdominal obesity (AO) reduction. To support lifestyle modification and self-management, we developed an information and communication technology-based self-management system-DialBeticsLite-with a fully automated dietary evaluation function for the treatment of AO. OBJECTIVE: The objective of this study was to evaluate the preliminary efficacy and feasibility of DialBeticsLite among Japanese office workers with AO. METHODS: A 2- to 3-month prospective single-arm pilot intervention study was designed to assess the effects of the intervention using DialBeticsLite. The information and communication technology system was composed of 4 modules: data transmission (body weight, blood pressure, blood glucose, and pedometer count); data evaluation; exercise input; and food recording and dietary evaluation. Eligible participants were workers who were aged ≥20 years and with AO (waist circumference ≥85 cm for men and ≥90 cm for women). Physical parameters, blood tests, nutritional intake, and self-care behavior were compared at baseline and after the intervention. RESULTS: A total of 48 participants provided completed data for analysis, which yielded a study retention rate of 100%. The average age was 46.8 (SD 6.8) years, and 92% (44/48) of participants were male. The overall average measurement rate of DialBeticsLite, calculated by dividing the number of days with at least one measurement by the number of days of the intervention, was 98.6% (SD 3.4%). In total, 85% (41/48) of the participants reported that their participation in the study helped them to improve their lifestyle. BMI, waist circumference, and visceral fat area decreased significantly after the intervention (P<.001). In addition, the daily calorie intake reduced significantly (P=.02). There was a significant improvement in self-care behavior in terms of exercise and diet (P=.001). CONCLUSIONS: Using DialBeticsLite was shown to be a feasible and potentially effective method for reducing AO by providing users with a motivational framework to evaluate their lifestyle behaviors.
RESUMO
An increase in nutrient levels due to eutrophication has considerable effects on lake ecosystems. Cladocerans are intermediate consumers in lake ecosystems; thus, they are influenced by both the bottom-up and top-down effects that occur as eutrophication progresses. The long-term community succession of cladocerans and the effects cladocerans experience through the various eutrophication stages have rarely been investigated from the perspective of the early-stage cladoceran community assemblage during lake formation. In our research, long-term cladoceran community succession was examined via paleolimnological analysis in the currently eutrophic Lake Fukami-ike, Japan. We measured the concentration of total phosphorus and phytoplankton pigments and counted cladoceran and other invertebrate subfossils in all layers of collected sediment cores, and then assessed changes in the factors controlling the cladoceran community over a 354-year period from lake formation to the present. The cladoceran community consisted only of benthic taxa at the time of lake formation. When rapid eutrophication occurred and phytoplankton increased, the benthic community was replaced by a pelagic community. After further eutrophication, large Daphnia and high-order consumers became established. The statistical analysis suggested that bottom-up effects mainly controlled the cladoceran community in the lake's early stages, and the importance of top-down effects increased after eutrophication occurred. Total phosphorus and phytoplankton pigments had positive effects on pelagic Bosmina, leading to the replacement of the benthic cladoceran community by the pelagic one. In contrast, the taxa established posteutrophication were affected more by predators than by nutrient levels. A decrease in planktivorous fish possibly allowed large Daphnia to establish, and the subsequent increase in planktivorous fish reduced the body size of the cladoceran community.
RESUMO
BACKGROUND: Recent research has led to the development of many information technology-supported systems for health care control, including systems estimating nutrition from images of meals. Systems that capture data about eating and exercise are useful for people with diabetes as well as for people who are simply on a diet. Continuous monitoring is key to effective dietary control, requiring systems that are simple to use and motivate users to pay attention to their meals. Unfortunately, most current systems are complex or fail to motivate. Such systems require some manual inputs such as selection of an icon or image, or by inputting the category of the user's food. The nutrition information fed back to users is not especially helpful, as only the estimated detailed nutritional values contained in the meal are typically provided. OBJECTIVE: In this paper, we introduce healthiness of meals as a more useful and meaningful general standard, and present a novel algorithm that can estimate healthiness from meal images without requiring manual inputs. METHODS: We propose a system that estimates meal healthiness using a deep neural network that extracts features and a ranking network that learns the relationship between the degrees of healthiness of a meal using a dataset prepared by a human dietary expert. First, we examined whether a registered dietitian can judge the healthiness of meals solely by viewing meal images using a small dataset (100 meals). We then generated ranking data based on comparisons of sets of meal images (850 meals) by a registered dietitian's viewing meal images and trained a ranking network. Finally, we estimated each meal's healthiness score to detect unhealthy meals. RESULTS: The ranking estimated by the proposed network and the ranking of healthiness based on the dietitian's judgment were correlated (correlation coefficient 0.72). In addition, extracting network features through pretraining with a publicly available large meal dataset enabled overcoming the limited availability of specific healthiness data. CONCLUSIONS: We have presented an image-based system that can rank meals in terms of the overall healthiness of the dishes constituting the meal. The ranking obtained by the proposed method showed a good correlation to nutritional value-based ranking by a dietitian. We then proposed a network that allows conditions that are important for judging the meal image, extracting features that eliminate background information and are independent of location. Under these conditions, the experimental results showed that our network achieves higher accuracy of healthiness ranking estimation than the conventional image ranking method. The results of this experiment in detecting unhealthy meals suggest that our system can be used to assist health care workers in establishing meal plans for patients with diabetes who need advice in choosing healthy meals.
RESUMO
Microcystis aeruginosa forms massive blooms in eutrophic freshwaters, where it is constantly exposed to lytic cyanophages. Unlike other marine cyanobacteria, M. aeruginosa possess remarkably abundant and diverse potential antiviral defense genes. Interestingly, T4-like cyanophage Ma-LMM01, which is the sole cultured lytic cyanophage infecting M. aeruginosa, lacks the host-derived genes involved in maintaining host photosynthesis and directing host metabolism that are abundant in other marine cyanophages. Based on genomic comparisons with closely related cyanobacteria and their phages, Ma-LMM01 is predicted to employ a novel infection program that differs from that of other marine cyanophages. Here, we used RNA-seq technology and in silico analysis to examine transcriptional dynamics during Ma-LMM01 infection to reveal host transcriptional responses to phage infection, and to elucidate the infection program used by Ma-LMM01 to avoid the highly abundant host defense systems. Phage-derived reads increased only slightly at 1 h post-infection, but significantly increased from 16% of total cellular reads at 3 h post-infection to 33% of all reads by 6 h post-infection. Strikingly, almost none of the host genes (0.17%) showed a significant change in expression during infection. However, like other lytic dsDNA phages, including marine cyanophages, phage gene dynamics revealed three expression classes: early (host-takeover), middle (replication), and late (virion morphogenesis). The early genes were concentrated in a single â¼5.8-kb window spanning 10 open reading frames (gp054-gp063) on the phage genome. None of the early genes showed homology to the early genes of other T4-like phages, including known marine cyanophages. Bacterial RNA polymerase (σ70) recognition sequences were also found in the upstream region of middle and late genes, whereas phage-specific motifs were not found. Our findings suggest that unlike other known T4-like phages, Ma-LMM01 achieves three sequential gene expression patterns with no change in host promoter activity. This type of infection that does not cause significant change in host transcriptional levels may be advantageous in allowing Ma-LMM01 to escape host defense systems while maintaining host photosynthesis.
RESUMO
The freshwater cyanobacterium Microcystis aeruginosa frequently forms toxic massive blooms and exists in an arms race with its infectious phages in aquatic natural environments, and as a result, has evolved extremely diverse and elaborate antiviral defense systems, including the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated genes (Cas) system. Here, to assess Microcystis population dynamics associated with exogenous mobile genetic elements such as phages and plasmids, we examined the temporal variation in CRISPR genotypes (CTs) by analyzing spacer sequences detected in a natural pond between June and October 2013 when a cyanobacterial bloom occurred. A total of 463,954 high-quality leader-end CRISPR sequences were obtained and the sequences containing spacers were classified into 31 previously reported CTs and 68 new CTs based on the shared order of the leader-end spacers. CT19 was the most dominant genotype (32%) among the 16 most common CTs, followed by CT52 (14%) and CT58 (9%). Spacer repertoires of CT19 showed mainly two different types; CT19origin, which was identical to the CT19 spacer repertoire of previously isolated strains, and CT19new+, which contained a new spacer at the leader-end of the CRISPR region of CT19origin, which were present in almost equal abundance, accounting for up to 99.94% of CT19 sequences. Surprisingly, we observed the spacer repertoires of the second to tenth spacers of CT19origin at the most leader-end of proto-genotype sequences of CT19origin. These were observed during the sampling in this study and our previous study at the same ecosystem in 2010 and 2011, suggesting these CTs persisted from 2011 to 2013 in spite of phage pressure. The leader-end variants were observed in other CT genotypes. These findings indicated an incomplete selective sweep of Microcystis populations. We explained the phenomenon as follow; the abundance of Microcystis varied seasonally and drastically, resulting that Microcystis populations experience a bottleneck once a year, and thereby founder effects following a bottleneck mean that older CTs have an equal chance of increasing in prevalence as the CTs generated following acquisition of newer spacers.
RESUMO
OBJECTIVES: To examine the prevalence of the willingness of patients with diabetes to use a self-management tool based on information and communication technology (ICT) such as personal computers, smartphones, and mobile phones; and to examine the patient characteristics associated with that willingness. RESEARCH DESIGN AND METHODS: We conducted a cross-sectional interview survey of 312 adults with diabetes at a university hospital in an urban area in Japan. Participants were classified into 2 groups: those who were willing to use an ICT-based self-management tool and those who were unwilling. Multiple logistic regression analysis was used to identify factors associated with the willingness, including clinical and social factors, current use of ICT, self-management practices, self-efficacy, and diabetes-related emotional distress. RESULTS: The mean age of the 312 participants was 66.3â years (SD=11.5) and 198 (63%) were male. Most of the participants (93%) had type 2 diabetes. Although only 51 (16%) currently used ICT-based self-management tools, a total of 157 (50%) expressed the willingness to use such a tool. Factors associated with the willingness included: not having nephropathy (OR=2.02, 95% CI 1.14 to 3.58); outpatient visits once a month or more (vs less than once a month, OR=2.13, 95% CI 1.13 to 3.99); current use of personal computers and/or smartphones (OR=4.91, 95% CI 2.69 to 8.98); and having greater diabetes-related emotional distress (OR=1.10, 95% CI 1.01 to 1.20). CONCLUSIONS: Approximately half of the patients showed interest in using an ICT-based self-management tool. Willing patients may expect ICT-based self-management tools to complement outpatient visits and to make self-management easier. Starting with patients who display the willingness factors might optimize programs based on such tools.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Hipoglicemiantes/uso terapêutico , Insulina/uso terapêutico , Aplicativos Móveis , Autocuidado/instrumentação , Smartphone , Idoso , Dieta para Diabéticos , Exercício Físico , Feminino , Humanos , Hipoglicemiantes/administração & dosagem , Insulina/administração & dosagem , Masculino , Pessoa de Meia-Idade , Cooperação do Paciente , Projetos Piloto , AutogestãoRESUMO
AIM: To test for the possible association between mitochondrial aldehyde dehydrogenase (ALDH2) promoter polymorphism and alcoholism. METHODS: Genotyping to identify the polymorphisms in 515 alcoholic patients and 361 normal controls was performed. RESULTS: There were no significant differences between the genotype and allele frequencies of the -357A/G polymorphism in alcoholics and normal controls. Linkage disequilibrium was observed between the promoter and exon 12 polymorphisms. CONCLUSION: These results suggest the ALDH2 promoter polymorphism does not affect the risk for alcoholism.