Comprehensive Metabolomic Comparison of Five Cereal Vinegars Using Non-Targeted and Chemical Isotope Labeling LC-MS Analysis

Vinegar is used as an acidic condiment and preservative worldwide. In Asia, various black vinegars are made from different combinations of grains, such as Sichuan bran vinegar (SBV), Shanxi aged vinegar (SAV), Zhenjiang aromatic vinegar (ZAV), and Fujian Monascus vinegar (FMV) in China and Ehime black vinegar in Japan (JBV). Understanding the chemical compositions of different vinegars can provide information about nutritional values and the quality of the taste. This study investigated the vinegar metabolome using a combination of GC-MS, conventional LC-MS, and chemical isotope labeling LC-MS. Different types of vinegar contained different metabolites and concentrations. Amino acids and organic acids were found to be the main components. Tetrahydroharman-3-carboxylic acid and harmalan were identified first in vinegar. Various diketopiperazines and linear dipeptides contributing to different taste effects were also detected first in vinegar. Dipeptides, 3-phenyllactic acid, and tyrosine were found to be potential metabolic markers for differentiating vinegars. The differently expressed pathway between Chinese and Japanese vinegar was tryptophan metabolism, while the main difference within Chinese vinegars was aminoacyl-tRNA biosynthesis metabolism. These results not only give insights into the metabolites in famous types of cereal vinegar but also provide valuable knowledge for making vinegar with desirable health characteristics.

Whole-Genome Sequencing Highlights Conservative Genomic Strategies of a Stress-Tolerant, Long-Lived Scleractinian Coral, Porites australiensis Vaughan, 1918

Massive corals of the genus Porites, common, keystone reef builders in the Indo-Pacific Ocean, are distinguished by their relative stress tolerance and longevity. In order to identify genetic bases of these attributes, we sequenced the complete genome of a massive coral, Porites australiensis. We developed a genome assembly and gene models of comparable quality to those of other coral genomes. Proteome analysis identified 60 Porites skeletal matrix protein genes, all of which show significant similarities to genes from other corals and even to those from a sea anemone, which has no skeleton. Nonetheless, 30% of its skeletal matrix proteins were unique to Porites and were not present in the skeletons of other corals. Comparative genomic analyses showed that genes widely conserved among other organisms are selectively expanded in Porites. Specifically, comparisons of transcriptomic responses of P. australiensis and Acropora digitifera, a stress-sensitive coral, reveal significant differences in regard to genes that respond to increased water temperature, and some of the genes expanded exclusively in Porites may account for the different thermal tolerances of these corals. Taken together, widely shared genes may have given rise to unique biological characteristics of Porites, massive skeletons and stress tolerance.

Whole-Genome Transcriptome Analyses of Native Symbionts Reveal Host Coral Genomic Novelties for Establishing Coral-Algae Symbioses

Reef-building corals and photosynthetic, endosymbiotic algae of the family Symbiodiniaceae establish mutualistic relationships that are fundamental to coral biology, enabling coral reefs to support a vast diversity of marine species. Although numerous types of Symbiodiniaceae occur in coral reef environments, Acropora corals select specific types in early life stages. In order to study molecular mechanisms of coral–algal symbioses occurring in nature, we performed whole-genome transcriptomic analyses of Acropora tenuis larvae inoculated with Symbiodinium microadriaticum strains isolated from an Acropora recruit. In order to identify genes specifically involved in symbioses with native symbionts in early life stages, we also investigated transcriptomic responses of Acropora larvae exposed to closely related, nonsymbiotic, and occasionally symbiotic Symbiodinium strains. We found that the number of differentially expressed genes was largest when larvae acquired native symbionts. Repertoires of differentially expressed genes indicated that corals reduced amino acid, sugar, and lipid metabolism, such that metabolic enzymes performing these functions were derived primarily from S. microadriaticum rather than from A. tenuis. Upregulated gene expression of transporters for those metabolites occurred only when coral larvae acquired their natural symbionts, suggesting active utilization of native symbionts by host corals. We also discovered that in Acropora, genes for sugar and amino acid transporters, prosaposin-like, and Notch ligand-like, were upregulated only in response to native symbionts, and included tandemly duplicated genes. Gene duplications in coral genomes may have been essential to establish genomic novelties for coral–algae symbiosis.

A New Dinoflagellate Genome Illuminates a Conserved Gene Cluster Involved in Sunscreen Biosynthesis

Photosynthetic dinoflagellates of the Family Symbiodiniaceae live symbiotically with many organisms that inhabit coral reefs and are currently classified into fifteen groups, including seven genera. Draft genomes from four genera, Symbiodinium, Breviolum, Fugacium, and Cladocopium, which have been isolated from corals, have been reported. However, no genome is available from the genus Durusdinium, which occupies an intermediate phylogenetic position in the Family Symbiodiniaceae and is well known for thermal tolerance (resistance to bleaching). We sequenced, assembled, and annotated the genome of Durusdinium trenchii, isolated from the coral, Favia speciosa, in Okinawa, Japan. Assembled short reads amounted to 670 Mb with ∼47% GC content. This GC content was intermediate among taxa belonging to the Symbiodiniaceae. Approximately 30,000 protein-coding genes were predicted in the D. trenchii genome, fewer than in other genomes from the Symbiodiniaceae. However, annotations revealed that the D. trenchii genome encodes a cluster of genes for synthesis of mycosporine-like amino acids, which absorb UV radiation. Interestingly, a neighboring gene in the cluster encodes a glucose-methanol-choline oxidoreductase with a flavin adenine dinucleotide domain that is also found in Symbiodinium tridacnidorum. This conservation seems to partially clarify an ancestral genomic structure in the Symbiodiniaceae and its loss in late-branching lineages, including Breviolum and Cladocopium, after splitting from the Durusdinium lineage. Our analysis suggests that approximately half of the taxa in the Symbiodiniaceae may maintain the ability to synthesize mycosporine-like amino acids. Thus, this work provides a significant genomic resource for understanding the genomic diversity of Symbiodiniaceae in corals.

Gut microbial composition of elderly women born in the Japanese longevity village Ogimi

Ogimi is one of Japan’s longevity villages and is located in Okinawa Prefecture. In this study, we focused on the elderly women living in the village, classified them into two groups based on whether or not they lived in Ogimi during the first 3 years of their lives, and compared the gut microbiota between the two groups. There were no differences in alpha and beta diversity; however, we found that the elderly women who lived in Ogimi during the first 3 years of their lives had a higher rate of Akkermansia muciniphila colonization in their guts.

Correlation-Based Deconvolution (CorrDec) To Generate High-Quality MS2 Spectra from Data-Independent Acquisition in Multisample Studies

Data-independent acquisition mass spectrometry (DIA-MS) is essential for information-rich spectral annotations in untargeted metabolomics. However, the acquired MS2 spectra are highly complex, posing significant annotation challenges. We have developed a correlation-based deconvolution (CorrDec) method that uses ion abundance correlations in multisample studies using DIA-MS as an update of our MS-DIAL software. CorrDec is based on the assumption that peak intensities of precursor and fragment ions correlate across samples and exploits this quantitative information to deconvolute complex DIA spectra. CorrDec clearly improved deconvolution of the original MS-DIAL deconvolution method (MS2Dec) in a dilution series of chemical standards and a 224-sample urinary metabolomics study. The primary advantage of CorrDec over MS2Dec is the ability to discriminate coeluting low-abundance compounds. CorrDec requires the measurement of multiple samples to successfully deconvolute DIA spectra; however, our randomized assessment demonstrated that CorrDec can contribute to studies with as few as 10 unique samples. The presented methodology improves compound annotation and identification in multisample studies and will be useful for applications in large cohort studies.

Rearrangement analysis of multiple bacterial genomes

Background

Genomes are subjected to rearrangements that change the orientation and ordering of genes during evolution. The most common rearrangements that occur in uni-chromosomal genomes are inversions (or reversals) to adapt to the changing environment. Since genome rearrangements are rarer than point mutations, gene order with sequence data can facilitate more robust phylogenetic reconstruction. Helicobacter pylori is a good model because of its unique evolution in niche environment.

Results

We have developed a method to identify genome rearrangements by comparing almost-conserved genes among closely related strains. Orthologous gene clusters, rather than the gene sequences, are used to align the gene order so that comparison of large number of genomes becomes easier. Comparison of 72 Helicobacter pylori strains revealed shared as well as strain-specific reversals, some of which were found in different geographical locations.

Conclusion

Degree of genome rearrangements increases with time. Therefore, gene orders can be used to study the evolutionary relationship among species and strains. Multiple genome comparison helps to identify the strain-specific as well as shared reversals. Identification of the time course of rearrangements can provide insights into evolutionary events.

Genetic diversity and DNA barcoding of the black fly (Diptera: Simuliidae) vectors of parasites causing human onchocerciasis in Guatemala

Genetic variation based on mitochondrial cytochrome c oxidase I (COI) and II (COII) sequences was investigated for three black fly nominal species, Simulium metallicum Bellardi complex, S. callidum Dyar and Shannon, and S. ochraceum Walker complex, which are vectors of human onchocerciasis from Guatemala. High levels of genetic diversity were found in S. metallicum complex and S. ochraceum complex with maximum intraspecific genetic divergences of 11.39% and 4.25%, respectively. Levels of genetic diversity of these nominal species are consistent with species status for both of them as they are cytologically complexes of species. Phylogenetic analyses revealed that the S. metallicum complex from Guatemala divided into three distinct clades, two with members of this species from several Central and South American countries and another exclusively from Mexico. The Simulium ochraceum complex from Guatemala formed a clade with members of this species from Mexico and Costa Rica while those from Ecuador and Colombia formed another distinct clade. Very low diversity in S. callidum was found for both genes with maximum intraspecific genetic divergence of 0.68% for COI and 0.88% for COII. Low genetic diversity in S. callidum might be a consequence of the result being informative of only recent population history of the species.

Creating a Reliable Mass Spectral-Retention Time Library for All Ion Fragmentation-Based Metabolomics

Accurate metabolite identification remains one of the primary challenges in a metabolomics study. A reliable chemical spectral library increases the confidence in annotation, and the availability of raw and annotated data in public databases facilitates the transfer of Liquid chromatography coupled to mass spectrometry (LC-MS) methods across laboratories. Here, we illustrate how the combination of MS2 spectra, accurate mass, and retention time can improve the confidence of annotation and provide techniques to create a reliable library for all ion fragmentation (AIF) data with a focus on the characterization of the retention time. The resulting spectral library incorporates information on adducts and in-source fragmentation in AIF data, while noise peaks are effectively minimized through multiple deconvolution processes. We also report the development of the Mass Spectral LIbrary MAnager (MS-LIMA) tool to accelerate library sharing and transfer across laboratories. This library construction strategy improves the confidence in annotation for AIF data in LC-MS-based metabolomics and will facilitate the sharing of retention time and mass spectral data in the metabolomics community.

Two divergent Symbiodinium genomes reveal conservation of a gene cluster for sunscreen biosynthesis and recently lost genes

Background

The marine dinoflagellate, Symbiodinium, is a well-known photosynthetic partner for coral and other diverse, non-photosynthetic hosts in subtropical and tropical shallows, where it comprises an essential component of marine ecosystems. Using molecular phylogenetics, the genus Symbiodinium has been classified into nine major clades, A-I, and one of the reported differences among phenotypes is their capacity to synthesize mycosporine-like amino acids (MAAs), which absorb UV radiation. However, the genetic basis for this difference in synthetic capacity is unknown. To understand genetics underlying Symbiodinium diversity, we report two draft genomes, one from clade A, presumed to have been the earliest branching clade, and the other from clade C, in the terminal branch.

Results

The nuclear genome of Symbiodinium clade A (SymA) has more gene families than that of clade C, with larger numbers of organelle-related genes, including mitochondrial transcription terminal factor (mTERF) and Rubisco. While clade C (SymC) has fewer gene families, it displays specific expansions of repeat domain-containing genes, such as leucine-rich repeats (LRRs) and retrovirus-related dUTPases. Interestingly, the SymA genome encodes a gene cluster for MAA biosynthesis, potentially transferred from an endosymbiotic red alga (probably of bacterial origin), while SymC has completely lost these genes.

Conclusions

Our analysis demonstrates that SymC appears to have evolved by losing gene families, such as the MAA biosynthesis gene cluster. In contrast to the conservation of genes related to photosynthetic ability, the terminal clade has suffered more gene family losses than other clades, suggesting a possible adaptation to symbiosis. Overall, this study implies that Symbiodinium ecology drives acquisition and loss of gene families.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4857-9) contains supplementary material, which is available to authorized users.

Revealing the genomic differences between two subgroups in Lactobacillus gasseri

Being an autochthonous species in humans, Lactobacillus gasseri is widely used as a probiotic for fermented products. We thoroughly compared the gene contents of 75 L. gasseri genomes and identified two intraspecific groups by the average nucleotide identity (ANI) threshold of 94%. Group I, with 48 strains, possessed 53 group-specific genes including the gassericin T cluster (9 genes) and N-acyl homoserine lactone lactonase. Group II, with 27 strains, including the type strain ATCC 33323, possessed group-specific genes with plasmid- or phage-related annotations. The genomic differences provide evidences for demarcating a new probiotic group within L. gasseri.

Visualization of consensus genome structure without using a reference genome

BACKGROUND

Standard graphical tools for whole genome comparison require a reference genome. However, any reference is also subject to annotation biases and rearrangements, and may not serve as the standard except for those of extensively studied model species. To fully exploit the rapidly accumulating sequence data from the recent sequencing technologies, genome comparison without any reference has been anticipated.

RESULTS

We introduce a circular genome visualizer to compare complete genomes of closely related species. This tool visualizes the position of orthologous gene clusters rather than actual sequences or their features, thereby achieving the comparative view without using a single reference genome. The essential information is the matrix of orthologous gene clusters whose positions (not sequences) are color-coded in circular graphics. As a demonstration, comparison of 14 Lactobacillus paracasei strains and one L. casei strain revealed not only large-scale rearrangements but also genomic islands that are strain-specific. Comparison of 73 Helicobacter pylori strains confirmed their genetic consistency and also revealed the three general patterns of large-scale genome inversions.

CONCLUSIONS

From the ample sequence information in the GenBank/ENA/DDBJ repository, we can reconstruct a genomic consensus for particular species. By visualizing multiple strains at a glance, we can identify conserved as well as strain-specific regions in multiply sequenced genomes. Positional consistency for orthologous genes provides information orthogonal to major sequence features such as the GC content or sequence similarity of marker genes. The positional comparison is therefore useful for identifying large-scale genome rearrangements or gene transfers.

Molecular phylogeny of Trypanosoma cruzi from Central America (Guatemala) and a comparison with South American strains

Molecular phylogenetic analysis was carried out for 21 strains of Trypanosoma cruzi, nine of which were obtained from Guatemala and 12 from South America. Phylogenetic trees were constructed using the nucleotide sequences of two nuclear gene regions, dihydrofolate reductase-thymidylate synthase (DHFR-TS) and trypanothione reductase (TR), and contiguous portions of two mitochondrial genes, cytochrome oxidase subunit II (COII) and reduced nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1). Possible genetic exchange between the rather divergent lineages of T. cruzi II from South America was suggested in the trees of the two nuclear genes. T. cruzi I strains obtained from Guatemala and Colombia were identical in all the genes examined, but other T. cruzi I isolates from South America were rather polymorphic in the DHFR-TS and mitochondrial genes. No genetic exchange was identified between T. cruzi I populations from Central and South America in the present study.

Strongyloides ratti: the role of interleukin-5 in protection against tissue migrating larvae and intestinal adult worms

To determine the role of interleukin-5 (IL-5) and eosinophils in protection against Strongyloides ratti, mice treated with anti-IL-5 monoclonal antibody (mAb) were infected with S. ratti larvae. Strongyloides ratti egg numbers in faeces (EPG) in mAb treated mice were higher than those in control mice on days 6 and 7 after inoculation. The numbers of migrating worms in mAb treated mice 36 h after inoculation were higher than those observed in control mice. Intestinal worm numbers in mAb treated mice 5 days after inoculation were higher than those in control mice. These results show that eosinophils effectively protected the host against S. ratti infection by mainly the larval stage in primary infections. The involvement of eosinophils in protection against secondary infection was also examined. Before secondary infection, mice were treated with anti-IL-5 mAb and infected with S. ratti. Patent infections were not observed in either mAb treated or control Ab treated mice. The numbers of migrating worms in the head and lungs of mAb treated mice increased to 60% of that in primary infected mice. Intestinal worms were not found in mAb treated mice or in control mice after oral implantation of adult worms. Eosinophils were therefore mainly involved in protection against tissue migrating worms in secondary infections.

Nematocidal activities of thiabendazole and ivermectin against the larvae of Strongyloides ratti and S. venezuelensis

With the aim of developing therapeutic agents for strongyloidosis, the disease caused by infection with Strongyloides stercoralis, we established a novel assay technique using S. ratti and S. venezuelensis as models for S. stercoralis. The newly developed assay technique was found to more accurately represent treatment-induced larval paralysis than existing assays. Our method uses paper disks impregnated with the test solution, which even allows materials that are sparingly soluble in water to be tested. An inverted microscope was used to observe the larval states, and these states were recorded using a digital camera. We observed the activities of ivermectin and thiabendazole against larvae and calculated larval motility and velocity. These two factors were then combined to determine the overall viability of larvae at selected concentrations. The activities of the anthelmintics were compared by calculating the concentrations at which 50% viability was demonstrated, or in other words, the concentration at which paralysis was caused in 50% of the individuals (50% paralysis concentration; PC(50)). Evaluations after 24h of exposure yielded the following reproducible PC(50) values for ivermectin and thiabendazole, respectively: S. ratti, 2.4 and 140 microM; and S. venezuelensis, 2.3 and 190 microM. After treatment with ivermectin, there was a tendency for larval motility to be greater than that of the controls at low concentrations, a result that might be associated with its mechanism of action.

Detection of kinetoplast DNA of Trypanosoma cruzi from dried feces of triatomine bugs by PCR

It is important to clarify the distribution of infected triatomine bugs in the endemic area of Chagas' disease for proper control. In the present study, we tried to detect T. cruzi kinetoplast DNA by PCR from dried triatomine feces collected from the house wall of an endemic area to assess the distribution of infected bugs more easily. The primers (P35/P36) were chosen to amplify the conserved region within the minirepeats of T. cruzi kinetoplast minicircle DNA. The kinetoplast DNA of T. cruzi could be actually detected in the dried feces collected from the wall of a brick-built house in Santa Cruz, Bolivia. Next, we examined the stability of T. cruzi kinetoplast DNA in the feces exposed to artificial environments. T. cruzi DNA was also detected by PCR in the feces left for 26 weeks at 25 degrees C and in those left for 4 weeks at 40 degrees C. The present study indicates that examination of dried feces on the wall can be an effective tool for surveillance of the natural infection of triatomine bugs that live in houses.

IL-4 reduces resistance of mice to Trypanosoma cruzi infection

The role of IL-4 has often been studied, especially in the Leishmania major infection model, but not in Trypanosoma cruzi infection. In the present study, the role of IL-4 in host defense against infection with the Tulahuen strain of T. cruzi was examined by depleting IL-4 with an anti-IL-4 monoclonal antibody in vivo. In both IL-4 depleted and control C57BL/6 mice, the parasitemia showed peaks on the 21st day of infection. Both parasitemia and mortality were decreased in IL-4 depleted mice compared with control mice when IFN-gamma and nitric oxide productions were increased in IL-4 depleted mice compared with control mice. The mice treated with N-nitro-L-arginine methyl ester, a competitive inhibitor of nitric oxide synthase, showed increased susceptibility to T. cruzi infection to the same level in both IL-4 depleted and control mice. Thus, it is suggested that endogenous IL-4 induces susceptibility to T. cruzi mainly by suppressing the production of IFN-gamma and nitric oxide, which has trypanocidal activity.

The effect of interleukin-4 on the induction of intestinal mast cells and chronological cytokine profiles during intestinal nematode Strongyloides ratti infection

The effect of interleukin-4 (IL-4) on the induction of intestinal mast cells and cytokine profiles during Strongyloides ratti infection was studied using IL-4 knockout (IL-4 KO) mice. The antigen-specific proliferative response of mesenteric lymph node cells was not impaired in IL-4 KO mice. The number of intestinal mast cells induced in IL-4 KO mice during S. ratti infection was 2- to 3-fold lower than that observed in WT mice. Intestinal mastocytosis had disappeared in IL-4 KO mice by day 21 postinfection, when significant mastocytosis continued to be observed in WT mice. In mesenteric lymphnode of IL-4 KO, IL-3 production decreased and mice IFN-gamma production significantly increased as compared with those of WT mice. The numbers of eggs excreted per gram of feces (EPG) by IL-4 KO mice were greater than those excreted by WT mice on day 6 postinfection, but no difference was observed in the subsequent period. In conclusion, intestinal mast cells are induced during S. ratti infection in the absence of IL-4, and IL-4 is not essential for protection against intestinal adult worms of S. ratti.

Effects of various treatments on the chemokinetic behavior of third-stage larvae of Strongyloides ratti on a sodium chloride gradient

In observations of the movements of the infective third-stage larvae of a rodent parasitic nematode, Strongyloides ratti, on a sodium chloride gradient set up on agarose plates, two types of chemokinetic behavior were seen: a unidirectional avoidance movement on initial placement of the larvae in unfavorable environmental conditions and a random dispersal movement on their placement within an area of favorable conditions. Track patterns were straight in the avoidance movement but included multiple changes of direction and loops in the dispersal movement. In the present study we examined the interventional activity of treatment with various enzymes, lectins, and chemicals by analyzing the unidirectional avoidance movements of the larvae. We observed that beta-glucosidase, hyaluronidase, beta-galactosidase, trypsin, protease, lipase, phospholipase C, soybean agglutinin, wheat germ agglutinin, and spermidine exerted inhibitory actions on those movements, which may be guided by the chemosensory function of this nematode.

Genetic structure of Trypanosoma cruzi in american continents: special emphasis on sexual reproduction in Central America

Isozyme analysis (12 enzymes: 14 loci) was conducted on 99 isolates of Trypanosoma cruzi: 77 from Guatemala, 5 from Mexico and 17 from South American countries. Analyses of 4 population-genetic indices were undertaken to assess the possibility of genetic exchange occurring among Guatemalan isolates. The results provide evidence for a degree of genetic exchange occurring among isolates from this relatively small geographical area. Previous studies of population genetics on T. cruzi might have failed to detect this phenomenon because they tended to use isolates originating far from one another, rendering gene exchange unlikely for geographical reasons. Phylogenetic data, presented here, show considerable differences in genetic structure between Central and South American isolates, suggesting that different biological and clinical properties might be expected. For example, there are differences in clinical syndromes between Central and South America, a situation discussed further here.

Strongyloides ratti: chemotactic responses of third-stage larvae to selected serum proteins and albumins

Experiments were carried out in vitro to investigate whether the sera of several animals as well as albumins and peptides might act as attractants for larvae of Strongyloides ratti. Samples of sera from several mammal species were dialysed and the aliquots were further centrifuged using ultrafiltration cartridges to remove any remaining small molecules. Additional test substances included commercially obtained ovalbumin, rat and bovine serum albumins, polypeptides such as peptone, tryptone and tryptose, amino nitrogens, monosaccharides, and reduced glutathione (triaminopeptide). Larvae were strongly attracted to the dialysed mammalian sera, which mainly consisted of serum albumin and globulins. Ov- and serum albumins, and polypeptides also acted as attractants. On the other hand, reduced glutathione, 16 kinds of amino acids and four kinds of monosaccharides did not attract this nematode.

Chemokinetic behavior of the infective third-stage larvae of Strongyloides ratti on a sodium chloride gradient

The movements of the infective third-stage larvae (L3) of a rodent parasitic nematode Strongyloides ratti were examined on a sodium chloride (NaCl) gradient set up on agarose plates. The movements of larvae were followed by observing their tracks on the surface of the agarose. The direction of movement depended on the NaCl concentration at the point of their initial placement on the gradient. Larvae placed at between 230 and 370 mM NaCl tended to migrate towards areas of lower concentration. On the other hand, when placed at concentrations less than 20 mM NaCl, larvae tended to migrate initially towards higher concentrations but did not linger in areas where the concentration was over approximately 80 mM NaCl. It seems that S. ratti L3, tested in vitro, prefer regions with a concentration of NaCl below 80 mM NaCl. Two typical chemokinetic behaviors are seen; a unidirectional avoidance movement when initially placed in unfavorable environmental conditions and a random dispersal movement when placed within an area of favorable conditions. Track patterns were straight in the avoidance movement but included multiple changes of direction and loops in the dispersal movement. This study introduces an assay system suitable for studying chemokinetic behavior of larvae of Strongyloides ratti.

Strongyloides ratti: thermokinetic behavior of third-stage larvae on a temperature gradient

We examined the thermokinetic behaviors of infective third-stage larvae (L3) of the rodent parasitic nematode Strongyloides ratti on temperature gradients using an in vitro agarose tracking assay method. Observed behaviors included both negative and positive thermokineses, the direction of movement depending both on the gradient temperature at which larvae were initially placed and on prior experience of culture temperature. Larvae isolated from rat feces cultured at 25 degrees C and placed on a gradient at temperatures between 22 degrees and 29 degrees C tended to move toward higher temperatures. At higher placement temperatures, most larvae moved little and showed no directional response, whereas at lower placement temperatures, many migrated toward cooler temperatures. At placement temperatures of 20 degrees C or below, few or no larvae moved toward the zone of higher temperature. Larvae isolated from rat feces cultured at 20 degrees C tended to migrate to a high temperature area regardless of placed temperature. Those cultured at 30 degrees C did not respond to the temperature gradient. L3 cultured at 30 degrees C were significantly less infective to rats than those cultured at 25 degrees or 20 degrees C. Additional experiments were designed to demonstrate thermokinetic behaviors during the period after reaching the L3 stage. Larvae incubated in double distilled water (DDW) for 24 h at 37 degrees C lost their ability to respond to lower temperatures, while in those incubated in DDW at 15 degrees and 25 degrees C, responses were still apparent. The thermokinetic behavior of S. ratti L3 is affected by surrounding environmental temperatures and this may have an important role in host finding.

The crucial role of granulocytes in the early host defense against Strongyloides ratti infection in mice

The involvement of granulocytes in the host early defense against the nematode, Strongyloides ratti, was studied. It was confirmed that granulocytes were effectively depleted for 4 days by anti-granulocyte monoclonal antibody (anti-Gr-1). To examine the involvement of granulocytes in the host defense against migrating larvae, 2,000 S. ratti infective larvae (L3) were inoculated subcutaneously 1 day after antibody treatment. The number of S. ratti eggs secreted in feces (EPG) was higher in the granulocyte-depleted group than in the control group. The number of migrating larvae also increased in the granulocyte-depleted group in accordance with the increase in EPG. Therefore granulocytes are crucial for the host early defense against migrating larvae of S. ratti. Next, the involvement of granulocytes in the intestinal early defense was examined. Mice were treated with the antibody on day 3 post-infection. On that day, almost all inoculated larvae reached the intestine and molted to become adults. EPG on day 5 post-infection was increased by the antibody treatment, but no effect was observed on intestinal worm numbers. The fecundity (EPG/worm number) of S. ratti adult worms in the granulocyte-depleted group was higher than that in the control group. Thus granulocytes are also involved in the intestinal early defense through suppressing fecundity of the adult worms. On the other hand, the depletion of granulocytes had no effect on the late adaptive response against S. ratti adult worms (e.g. number of intestinal mucosal mast cells, time of worm expulsion). These results suggest that granulocytes are mainly involved in the host early defense against parasites.

Strongyloides ratti: additive effect of testosterone implantation and carbon injection on the susceptibility of female mice

A sex-related difference in host susceptibility to Strongyloides ratti was previously known. Male mice were more susceptible to S. ratti infection and the difference was seen against migrating larvae under the regulation of testosterone. Against migrating larvae, macrophages were assumed to play important roles in host natural immunity. On the basis of these findings, to examine the effect of testosterone on macrophages we treated female mice with testosterone and/or carbon to block the function of macrophages. Mice were then infected with third-stage larvae of S. ratti. By counting of the migrating larvae in the cranial cavity at 36 h after infection the effect of each treatment was assayed. Testosterone treatment alone (Te) or carbon injection alone (Ca) effectively increased the worm recovery. Given together, Te and Ca (Te + Ca) significantly increased the worm recovery to levels almost equal to the sum of those achieved with Te and Ca. The serum testosterone concentration was elevated in mice that had undergone Te and Te + Ca at the time of worm recovery. Surprisingly, the serum testosterone concentration reached after Te + Ca was elevated more than that attained by Te. The same experiment with a half-dose of Te and Ca (Te half + Ca) resulted in the same testosterone concentration achieved with Te and resulted in a worm recovery almost equal to the sum of that achieved with Te and Ca. These results clearly showed that Te and Ca had an additive effect on the recovery of migrating S. ratti larvae. Testosterone had an effect after macrophages had been blocked. The relationship between testosterone and macrophage function during S. ratti infection is discussed.

Strongyloides ratti: migration study of third-stage larvae in rats by whole-body autoradiography after 35S-methionine labeling

In order to clarify the migration pathway of Strongyloides ratti, Wistar rats were given 5,000 35S-labeled infective larvae subcutaneously and killed at 10, 15, 20, 25, 30, 40, and 50 hr postinfection. Prior to inoculation, the specific radioactivity level was assessed in the labeled larvae using a scintillation counter. The frozen rat specimens were sectioned at 50 microm, and the sections were freeze-dried and mounted on X-ray film in darkness. The labeled larvae appeared as dark spots on the film after 14 days of exposure. The infected larvae remained at the inoculated site (lower abdomen) until 10 hr after infection. Some larvae were found in the head portion, whereas others existed sporadically in the skin, liver, and lungs at 15 hr. After 20 and 25 hr, the majority of larvae had accumulated in the head portion. Many larvae appeared in the cranial and nasal cavities; however, no larvae were found in any other organs or tissues. At 30 hr, most larvae had begun to accumulate in the ethmoid region again. At 40 and 50 hr, some larvae were recognized in the ethmoid region, and most had already reached the small intestine. This suggests that the larvae directly move to the nasofrontal portion through the subcutis, rather than migrating to the head through either the viscera, ascending vessels, or the foramen occipital magnum.

Characterisation of Trypanosoma cruzi populations by DNA polymorphism of the cruzipain gene detected by single-stranded DNA conformation polymorphism (SSCP) and direct sequencing

Fifty fresh isolates of Trypanosoma cruzi from Triatoma dimidiata vectors and 31 from patients with Chagas' disease were analysed for DNA polymorphisms within the 432-bp core region of the cruzipain gene which encodes the active site of cathepsin L-like cystein proteinase. The cruzipain gene showed signs of polymorphism consisting of four different DNA sequences in Central and South American isolates of T. cruzi. The PCR fragments of Guatemalan isolates could be divided into three groups, Groups 1, 2 and 3, based on different patterns of single-stranded DNA conformation polymorphism. All of the strains isolated from Brazil, Chile, and Paraguay, except for the CL strain, showed a Group 4 pattern. Two to four isolates from each group were analysed by cloning and sequencing. A silent mutation occurred between Groups 1 and 2, and five nucleotides and two aa substitutions were detected between Groups 1 and 3. The DNA sequence of Group 4 contained five nucleotides and one aa substitution from Group 1. All of the DNA sequences corresponded well with the single-stranded DNA conformation polymorphism. The Group 1 isolates, the majority in the Guatemalan population (70/81, 86.4%), were isolated from both triatomines and humans, but Group 3 were isolated only from humans. Moreover, the Group 2 isolates were detected only in triatomine vectors (9/50; 18%), but never in humans (0/32, P<0.05) suggesting that this group has an independent life-cycle in sylvatic animals and is maintained by reservoir hosts other than humans.

Plants used in Guatemala for the treatment of protozoal infections. I. Screening of activity to bacteria, fungi and American trypanosomes of 13 native plants

Extracts were prepared from 13 native plants used for the treatment of protozoal infections. Activity against bacteria and fungi was demonstrated by dilution procedures; Trypanosoma cruzi was evaluated in vitro against epimastigote and trypomastigotes and in vivo against trypomastigotes. In active extracts, toxicity was evaluated by Artemia salina nauplii, oral acute toxicity (1-5 g/kg) and oral and intraperitoneal subacute toxicity in mice (500 mg/kg). From the plants screened, six showed activity (< or = 2 mg/ml) against bacteria, three against yeasts, five against Microsporum gypseum and five against T. cruzi in vitro and/or in vivo. In vitro and in vivo activity was demonstrated by Neurolaena lobata and Solanum americanum; in vitro or in vivo activity was shown by Acalypha guatemalensis, Petiveria alliacea and Tridax procumbens. Toxicity studies showed that extracts from S. americanum are toxic to A. salina (aqueous, 160 ppm). None showed acute or oral toxicity to mice; S. americanum showed intraperitoneal subacute toxicity.

Genetic structure of Trypanosoma cruzi in Central America and its comparison with South American strains

Genetic characterization by isozyme analysis was performed on 68 isolates of Trypanosoma cruzi; 57 from Guatemala in Central America and 11 from South American countries. Ten zymodemes (isozyme patterns) were identified by examining zymograms of 12 enzymes (13 loci). These zymodemes were classified to 3 major distinctive groups: (1) major Guatemalan, (2) minor Guatemalan and (3) unique South American, by the genetic distances and the phylogenetic dendrogram drawn by UPGMA. Based on the results obtained, genetic structures and phylogenetic relations of T. cruzi in Guatemala and South America are discussed. Clonal reproduction seemed to be consistent with the observation of deviation from Hardy-Weinberg equilibrium in several loci.

Successful control of onchocerciasis vectors in San Vicente Pacaya, Guatemala, 1984-1989

Between 1984 and 1989, the onchocerciasis-vector control zone on the pilot area of San Vicente Pacaya, Guatemala, which had been subject to experimental control since 1979, was extended from 91.3 to 148.6 km2. Temephos was used as a larvicide against Simulium ochraceum s.l. the target species. As a new strategy, only breeding sites with water discharges of 0.1-10 litres/s were treated, every 2 weeks. This approach provided a substantial reduction in effort, number of treated sites, time and cost. To assess the effect of the temephos, nine sites were selected in which standardized collections of adult Simulium were made twice a month, by human bait. There was an obvious difference between the pre- and post-control mean densities of flies at each site. In the northern area, which includes the Lavaderos, Barretal, Colina and Rodeo sites, the biting density in 1979, before treatment, varied between 10 and 64 flies/man-hour (FMH). Four years later, this had been reduced to 0.1-3.2 FMH, and by the end of the present study, in 1989, the mean density was zero FMH. In the southern area, which lies south-east of Lavaderos (and includes Guachipilin, Ingerto, Pena Blanca and Sierra Morena), the density during the pre-control phase was 24 FMH at one of the two sites investigated at the time and 39.3 FMH at the other. It fell to 0.1-0.5 FMH after 5 years of control and to zero (three sites) or close to zero (< or = 0.5 FMH; one site) for the last 4 years of the present study. To assess the effect of vector control on onchocerciasis prevalence and incidence, 1280 residents from six endemic communities, out of 12,000 permanent inhabitants, were examined. In Santa Cruz, Patrocinio and Los Rios, the prevalence of skin microfilariae in the subjects from each community fell from 8.1%-37.8% during the pretreatment, base-line period to 0.0%-31.5% when the study foci were totally integrated into the vector-control operation following treatment. Incidence among children (aged < or = 9 years) varied from 0%-25% for the period 1982-1984 but, thereafter, not a single case appeared in four of the six study communities (Santa Cruz, Patrocinio, Los Rios and Berlin). Incidence in Guachipilin did not decline appreciably, probably because of human migration into the area from other onchocerciasis foci. The prevalence of nodules followed a similar trend to those of the prevalence and incidence of skin microfilariae, falling from 9.1%-45.0% pre-control to 1.8%-14.3% 10 years later.

Rapid expulsion of the intestinal trematodes Echinostoma trivolvis and E. caproni from C3H/HeN mice after infection with Nippostrongylus brasiliensis

The number of goblet cells in the small intestines of C3H/HeN mice increased rapidly following their infection with about 500 third-stage larvae (L3) of the intestinal nematode Nippostrongylus brasiliensis. The number of goblet cells reached its peak on day 9 postinfection (p.i.). Worm burdens in the hosts' small intestines were determined following a challenge infection with encysted metacercariae of the intestinal trematodes Echinostoma trivolvis or E. caproni on days 8 and 16 after primary infections with N. brasiliensis. All metacercariae of E. trivolvis or E. caproni used to challenge the hosts on day 8 p.i. were expelled. Considerable numbers of E. trivolvis (48.6%) and E. caproni (67.1%) remained in the intestines of hosts challenged with these echinostomes on day 16 p.i. All the controls used for E. trivolvis and E. caproni infections without primary infections with N. brasiliensis showed recovery rates greater than 70%. An enzyme-linked immunosorbent assay (ELISA) showed that the IgM titer rose remarkably and plateaued on day 11 p.i. No marked rise in the IgG or IgA titer occurred during the experiment. These results indicate that mucins increased by hyperplastic goblet cells associated with primary infections with N. brasiliensis are responsible for a rapid expulsion of the worms of the challenge infection with E. trivolvis or E. caproni from the mouse host.

Rapid expulsion of the intestinal trematodes Echinostoma trivolvis and E. caproni from C3H mice by trapping with increased goblet cell mucins

Echinostoma trivolvis (Cort, 1914) adults were rejected from C3H mice by 15 days post-exposure, corresponding to the increase in the number of goblet cells. Homologous and heterologous infections with the allopatric species E. caproni (Richard, 1964) were used to confirm the effect of increased secretion of goblet cell mucins in rejecting metacercariae of challenge infections of E. trivolvis or E. caproni on days 10, 16 and 20 p.i. after primary infections of E. trivolvis metacercariae. Five-day-old juveniles of E. trivolvis and E. caproni, which were recovered from C3H mice or hamsters, were also used for challenge infections on day 10 p.i. The metacercariae and juveniles, which were challenged homologously and heterologously on day 10 p.i., were almost all expelled. The metacercariae of E. trivolvis, which were challenged homologously on day 16, were completely rejected, but only a few challenged metacercariae of E. caproni in heterologous infection were recovered. Considerable numbers of E. caproni were recovered when challenge infections with the metacercariae were done on day 20 p.i., while only a small number of E. trivolvis was recovered. All controls without primary infections showed a recovery rate of over 50% of the worms. These results indicate that increased secretion of mucins by hyperplastic goblet cells associated with primary infections of E. trivolvis may be responsible for the expulsion of worms challenged homologously with E. trivolvis and heterologously with E. caproni from the mouse host.

Cross-resistance between Strongyloides venezuelensis and S. ratti in mice

Cross-resistance between Strongyloides venezuelensis and S. ratti was tested in mice. The mice were immunized with S. ratti and challenged with infective filariform larvae or larvae recovered from the lungs of mice, of a heterologous species, S. venezuelensis. In this system, cross-resistance was expressed to the intestinal stage but not to the migrating stage of the parasite. Anti-interleukin (IL)-5 monoclonal antibody (mAb) treatment showed that peripheral blood eosinophilia after infection with both species of the genus Strongyloides was dependent on IL-5. Cross-resistance expressed to the intestinal stages was inhibited partially by injection of anti-IL-5 mAb.

Regulatory effect of anti-interleukin-5 monoclonal antibody on intestinal worm burden in a primary infection with strongyloides venezuelensis in mice

The intestinal worm burden in Strongyloides venezuelensis-infected mice was influenced by treatment with anti-interleukin-5 (IL-5) monoclonal antibody (NC17) when NC17 was given to mice 3-7 days before infection. The present study has examined the involvement of IL-5 in susceptibility at different in the development of the parasite in the host. The results show that the number of tissue-migrating larvae recovered from the lungs in a primary infection was not affected by anti-IL-5 monoclonal antibody treatment, whereas intestinal worm counts increased in mice treated with 0.25-1 mg of NC17. In mice treated with 0.1 mg of NC17, adult worm recovery was not significantly different from non-treated controls. Peripheral and tissue eosinophilia were not observed in the early phase of infection (days 4-8). Six days after transfer of lung-stage larvae to NC17-treated mice, adult worm recovery was higher than that of control mice. These results suggest that non-eosinophil response(s), which were dependent on IL-5, were involved in the initial establishment of the intestinal stage of S. venezuelensis in mice. We discuss the mechanisms that control the susceptibility to the parasite from the viewpoint of host defence.

The role of IL-5 in the immune responses to nematodes in rodents

In this review, Masataka Korenoga and Isoo Toda discuss the role of interleukin 5 (IL-5) in immune responses caused by parasitic infections. Recent studies have shown that eosinophilia in parasitic infections is dependent on IL-5. Although eosinophils have been thought to be potent effector cells (from results of experiments, in vitro), their role in protective immunity to parasites is controversial.

Prolonged normothermic ischaemia of human cirrhotic liver during hepatectomy: a preliminary report

To evaluate the tolerance of the cirrhotic liver to extended warm ischaemia, 47 patients with cirrhosis who underwent liver resection over a 4-year period were studied retrospectively. Three groups of patients were identified. In group 1 (14 patients) liver resection was performed under conditions of portal triad occlusion ranging from 50 to 75 (mean 57.1) min. Group 2 (12 patients) was treated with portal occlusion for a period ranging from 30 to 42 (mean 33.1) min. Group 3 comprised 21 patients who underwent hepatectomy using conventional techniques. Mean blood loss was significantly reduced by portal triad occlusion (819 ml in group 1, 523 ml in group 2) compared with the conventional technique (1652 ml in group 3) (P < 0.05, group 1 versus group 3; P < 0.01, group 2 versus group 3). Hospital death occurred in three of the 21 patients in group 3 but in no patient who underwent portal triad occlusion. The morbidity rate was lower in the two occlusion groups (four of 26 patients) than in group 3 (six of 21). Bilirubin metabolism was substantially better after surgery in the occlusion groups (P < 0.05, groups 1 and 2 versus group 3 at day 14). Although the serum levels of transaminases were significantly raised until day 3 in patients undergoing long-term occlusion, the cirrhotic liver withstood the ischaemia-reperfusion insult, as assessed by changes in hepatic microcirculation, lipid peroxidation and the morphology of hepatic sinusoids. It is concluded that prolonged ischaemia during liver resection can be sustained in patients with cirrhosis and without high-risk factors.

Fibrolamellar hepatocellular carcinoma coexistent with a hepatocellular carcinoma of common type: report of a case

A case of small fibrolamellar hepatocellular carcinoma (HCC) coexistent with a HCC of common type is herein reported. A 56-year-old man was diagnosed as having multi-nodular type HCC with liver cirrhosis. The serum alpha-fetoprotein (AFP) level was slightly increased. The patient underwent a partial caudate lobectomy and lateral segmentectomy. Histologically, both resected tumors were small HCCs measuring less than 2 cm in diameter. One was a fibrolamellar type located in the caudate lobe, while the other was the common type in the lateral segment of the liver. Positive immunohistochemical staining for AFP was observed in the tumor cells of the HCC of common type but was not observed in the fibrolamellar HCC. We also reviewed previously reported cases of fibrolamellar HCC in Japan, and discussed the clinicopathologic implications of this disease.