An enhancer trap system to track developmental dynamics in Marchantia polymorpha.

A combination of streamlined genetics, experimental tractability and relative morphological simplicity compared to vascular plants makes the liverwort Marchantia polymorpha an ideal model system for studying many aspects of plant biology. Here we describe a transformation vector combining a constitutive fluorescent membrane marker with a nuclear marker that is regulated by nearby enhancer elements and use this to produce a library of enhancer trap lines for Marchantia. Screening gemmae from these lines allowed the identification and characterization of novel marker lines, including markers for rhizoids and oil cells. The library allowed the identification of a margin tissue running around the thallus edge, highlighted during thallus development. The expression of this marker is correlated with auxin levels. We generated multiple markers for the meristematic apical notch region, which have different spatial expression patterns, reappear at different times during meristem regeneration following apical notch excision and have varying responses to auxin supplementation or inhibition. This reveals that there are proximodistal substructures within the apical notch that could not be observed otherwise. We employed our markers to study Marchantia sporeling development, observing meristem emergence as defining the protonema-to-prothallus stage transition, and subsequent production of margin tissue during the prothallus stage. Exogenous auxin treatment stalls meristem emergence at the protonema stage but does not inhibit cell division, resulting in callus-like sporelings with many rhizoids, whereas pharmacologically inhibiting auxin synthesis and transport does not prevent meristem emergence. This enhancer trap system presents a useful resource for the community and will contribute to future Marchantia research.

What can hornworts teach us?

The hornworts are a small group of land plants, consisting of only 11 families and approximately 220 species. Despite their small size as a group, their phylogenetic position and unique biology are of great importance. Hornworts, together with mosses and liverworts, form the monophyletic group of bryophytes that is sister to all other land plants (Tracheophytes). It is only recently that hornworts became amenable to experimental investigation with the establishment of Anthoceros agrestis as a model system. In this perspective, we summarize the recent advances in the development of A. agrestis as an experimental system and compare it with other plant model systems. We also discuss how A. agrestis can help to further research in comparative developmental studies across land plants and to solve key questions of plant biology associated with the colonization of the terrestrial environment. Finally, we explore the significance of A. agrestis in crop improvement and synthetic biology applications in general.

An optimized transformation protocol for Anthoceros agrestis and three more hornwort species.

Land plants comprise two large monophyletic lineages, the vascular plants and the bryophytes, which diverged from their most recent common ancestor approximately 480 million years ago. Of the three lineages of bryophytes, only the mosses and the liverworts are systematically investigated, while the hornworts are understudied. Despite their importance for understanding fundamental questions of land plant evolution, they only recently became amenable to experimental investigation, with Anthoceros agrestis being developed as a hornwort model system. Availability of a high-quality genome assembly and a recently developed genetic transformation technique makes A. agrestis an attractive model species for hornworts. Here we describe an updated and optimized transformation protocol for A. agrestis, which can be successfully used to genetically modify one more strain of A. agrestis and three more hornwort species, Anthoceros punctatus, Leiosporoceros dussii, and Phaeoceros carolinianus. The new transformation method is less laborious, faster, and results in the generation of greatly increased numbers of transformants compared with the previous method. We have also developed a new selection marker for transformation. Finally, we report the development of a set of different cellular localization signal peptides for hornworts providing new tools to better understand the hornwort cell biology.

Muscle wasting assessment tools for prostate cancer.

Prostate cancer and its treatment may induce muscle wasting. Body composition and muscle functionality are rarely assessed in patients with prostate cancer from developing countries due to the limited availability of high-quality equipment for routine diagnosis. This cross-sectional study evaluated the association between several simplistic techniques for assessing muscle mass and function with a more complex standard of reference for muscle wasting among Mexican men with prostate cancer. Muscle wasting was highly prevalent, yet it was presumably associated with aging rather than cancer and its treatment itself. The restricted availability of specific equipment in clinical settings with technological limitations supports using unsophisticated techniques as surrogate measurements for muscle wasting. The left-arm handgrip dynamometry displayed the highest correlation with the standard of reference and exhibited an acceptable predicted probability for muscle estimation. Combining several simplistic techniques may be preferable. We also developed and internally validated a manageable model that helps to identify elderly patients with prostate cancer at risk of muscle depletion and impairment. These findings promote the early recognition and treatment of muscle wasting alterations occurring among older adults with prostate cancer.

Nutritional imbalances in a Mexican vegan group: urgent need for country-specific dietary guidelines.

Introduction: Introduction: vegan diets exclude the consumption of animal-derived products, and health advantages have been reported when followed. However, heterogeneous eating habits, food availability, and sociocultural characteristics among regions could lead to different physiological results. Case reports: twelve patients following a strict vegan diet for an uninterrupted period of ≥ 3 years were subjected to clinical assessment. Patients significantly exceeded the suggested intake for sugar, presented six mineral deficiencies, and exhibited three vitamins below the recommended consumption. We further identified hyperglycemia, hypertriglyceridemia, subnormal serum vitamin B12 concentrations, as well as macrocytosis and microcytic anemia in several participants. Discussion: this Mexican vegan diet is strongly influenced by endemic and cultural adaptations that could limit the benefits reported in other populations. Professional guidance is required to avoid specific deficiencies with potential repercussions. We urge country-specific vegan guidelines considering local eating habits, food availability, and sociocultural perspectives around food.

Introducción: Introducción: la dieta vegana excluye el consumo de productos de origen animal y se ha vinculado con una disminución del riesgo de morbimortalidad. Sin embargo, los distintos hábitos alimentarios entre países podrían condicionar los beneficios reportados para las dietas basadas en vegetales. Casos clínicos: doce pacientes siguiendo una estricta dieta vegana por ≥ 3 años se sometieron a una evaluación clínica. Exhibieron una ingestión de azúcar que supera el consumo sugerido, presentaron tres deficiencias vitamínicas y seis de minerales. Se identificó la presencia de hiperglucemia, hipertrigliceridemia, concentraciones séricas subnormales de vitamina B12, macrocitosis y anemia microcítica en varios participantes. Discusión: la dieta vegana de este grupo resultó fuertemente influenciada por adaptaciones culturales que podrían limitar los beneficios reportados en otras poblaciones. Se requiere orientación profesional para evitar desequilibrios nutricionales. Enfatizamos la necesidad del desarrollo de guías alimentarias y de práctica clínica que consideren los hábitos alimentarios locales, la disponibilidad de alimentos en la región y las perspectivas socioculturales en torno a la dieta vegana.

Krukenberg tumor as an incidental finding in a full-term pregnancy: a case report.

BACKGROUND: Krukenberg tumor is a rare metastatic tumor of the ovary with histopathological features known as signet ring cells. It usually develops in women around 45 years of age. However, here we describe an uncommon case in a 38-year-old pregnant woman. We report this case due to our unusual findings, the uncommon presentation in this younger age bracket, its diagnostic challenge, and poor prognosis. CASE PRESENTATION: We describe a unique case of a young Mexican woman with a history of painful vaginal bleeding at 13 weeks of pregnancy and treated for abruptio placentae. In her routine prenatal visit at week 20 of pregnancy, she was found to have a uterine fundus exceeding the expected measure for her gestational age and was referred to the hospital to discard polyhydramnios. Upon admission, a pelvic ultrasound was performed displaying normal findings in a 25-week pregnancy, and also showing bilateral enlarged ovaries with heterogeneous echogenicity. Magnetic resonance imaging revealed a left tumoral lesion with dimensions of 22.1 × 13.6 × 16.3 cm presenting regular lobulated contours with displacement of peripheral structures and mild compression of the bladder, the left ureter, and the inferior vena cava. The lesion was heterogeneous with irregular borders. The patient was scheduled for a cesarean section; during the operation, the abdominal cavity showed bilateral tumors compatible with MRI findings. The ovarian tumors were sent to pathology, and the results showed poorly differentiated mucinous adenocarcinoma (World Health Organization grade III) with extensive signet ring cells, indicative of a Krukenberg tumor. CONCLUSION: This case report describes an uncommon example of a young pregnant woman without identifiable risk factors for gastric cancer who manifested a Krukenberg tumor. This incidental finding suggests that pregnancy obscured the cancer's clinical appearance. The rapid deterioration in the patient's condition corresponds to what is described in the literature. The limited information regarding this neoplasm in Mexico and the torpid evolution of the case highlight the importance of conducting additional studies to generate therapeutic interventions aimed at increasing overall survival.

Effects of nonnutritive sweeteners on body weight and BMI in diverse clinical contexts: Systematic review and meta-analysis.

There is an ongoing debate about the possible influences of nonnutritive sweeteners (NNS) on body weight. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) with NNS to assess their impact on body weight. We systematically searched for RCTs at least 4 weeks in duration, evaluating the effect of NNS on body weight, both in subjects with healthy weight and in subjects with overweight/obesity at any age, and compared the effects of NNS vs caloric and noncaloric comparators. The primary outcome was the difference in body weight between NNS and comparators. Twenty studies were eligible (n = 2914). Participants consuming NNS showed significant weight/BMI differences favouring NNS compared with nonusers. Grouping by nature of comparator revealed that NNS vs placebo/no intervention and NNS vs water produced no effect. When comparing NNS vs sucrose, significant weight/BMI differences appeared favouring NNS. Consumption of NNS led to significantly negative weight/BMI differences in unrestricted energy diets, but not in weight-reduction diets. Participants with overweight/obesity and adults showed significant favourable weight/BMI differences with NNS. Data suggest that replacing sugar with NNS leads to weight reduction, particularly in participants with overweight/obesity under an unrestricted diet, information that could be utilized for evidence-based public policy decisions.

Edulcorantes no calóricos en la mujer en edad reproductiva: documento de consenso / Non-caloric sweeteners in women of reproductive age: a consensus document

Los edulcorantes no calóricos (ENC) son aditivos de alimentos que se utilizan para sustituir azúcares y potencialmente para reducir la ingesta energética. Existe un debate científico en torno a los beneficios reales de su uso. Los ENC son sustancias ampliamente evaluadas en la literatura científica. Su seguridad es revisada por las agencias regulatorias internacionales del campo de la salud. Los profesionales de la salud y los consumidores con frecuencia carecen de educación e información rigurosa, objetiva y sustentada en la evidencia científica y el juicio clínico sobre el uso de aditivos en los alimentos. Los ENC se han empleado como sustitutos de la sacarosa, en especial por las personas con diabetes mellitus y obesidad. Sin embargo, se han planteado inquietudes relacionadas con su posible asociación con el parto pretérmino y con su uso durante el embarazo y la lactancia, ante la posibilidad de consecuencias metabólicas o de otra índole en la madre o en el neonato. Este análisis de la evidencia en ginecología y obstetricia presenta una revisión que intenta responder a preguntas que habitualmente se hacen al respecto los profesionales de la salud y sus pacientes. En este documento se evalúan diversas publicaciones científicas bajo el tamiz de la medicina basada en la evidencia y del marco regulatorio para aditivos de alimentos con el fin dilucidar si el uso de ENC en las mujeres durante las etapas críticas del embarazo y la lactancia supone o no un posible riesgo

Non-nutritive sweeteners (NNS) are food additives that have been used as a possible tool to reduce energy and sugar intake. There is a scientific debate around the real benefits of their use. NNS are substances widely evaluated in the scientific literature. Their safety is reviewed by international regulatory health agencies. Health professionals and consumers often lack education and objective information about food additives based on the best scientific evidence. NNS have been used as a substitute for sucrose, especially by people with diabetes mellitus and obesity. However, concerns related to their possible association with preterm birth have been raised, and also with their use during pregnancy and lactation because of the possibility of metabolic or other consequences in both the mother and offspring. This analysis of the evidence in gynecology and obstetrics presents a review of the most commonly asked questions regarding this matter by health professionals and their patients. This document evaluates a diversity of scientific publications under the sieve of evidence-based medicine and the regulatory framework for food additives to elucidate whether the use of NNS in women in these critical stages of pregnancy and breastfeeding represents a potential risk

[Non-caloric sweeteners in women of reproductive age - A consensus document]. / Edulcorantes no calóricos en la mujer en edad reproductiva: documento de consenso.

INTRODUCTION: Non-nutritive sweeteners (NNS) are food additives that have been used as a possible tool to reduce energy and sugar intake. There is a scientific debate around the real benefits of their use. NNS are substances widely evaluated in the scientific literature. Their safety is reviewed by international regulatory health agencies. Health professionals and consumers often lack education and objective information about food additives based on the best scientific evidence. NNS have been used as a substitute for sucrose, especially by people with diabetes mellitus and obesity. However, concerns related to their possible association with preterm birth have been raised, and also with their use during pregnancy and lactation because of the possibility of metabolic or other consequences in both the mother and offspring. This analysis of the evidence in gynecology and obstetrics presents a review of the most commonly asked questions regarding this matter by health professionals and their patients. This document evaluates a diversity of scientific publications under the sieve of evidence-based medicine and the regulatory framework for food additives to elucidate whether the use of NNS in women in these critical stages of pregnancy and breastfeeding represents a potential risk.

INTRODUCCIÓN: Los edulcorantes no calóricos (ENC) son aditivos de alimentos que se utilizan para sustituir azúcares y potencialmente para reducir la ingesta energética. Existe un debate científico en torno a los beneficios reales de su uso. Los ENC son sustancias ampliamente evaluadas en la literatura científica. Su seguridad es revisada por las agencias regulatorias internacionales del campo de la salud. Los profesionales de la salud y los consumidores con frecuencia carecen de educación e información rigurosa, objetiva y sustentada en la evidencia científica y el juicio clínico sobre el uso de aditivos en los alimentos. Los ENC se han empleado como sustitutos de la sacarosa, en especial por las personas con diabetes mellitus y obesidad. Sin embargo, se han planteado inquietudes relacionadas con su posible asociación con el parto pretérmino y con su uso durante el embarazo y la lactancia, ante la posibilidad de consecuencias metabólicas o de otra índole en la madre o en el neonato. Este análisis de la evidencia en ginecología y obstetricia presenta una revisión que intenta responder a preguntas que habitualmente se hacen al respecto los profesionales de la salud y sus pacientes. En este documento se evalúan diversas publicaciones científicas bajo el tamiz de la medicina basada en la evidencia y del marco regulatorio para aditivos de alimentos con el fin dilucidar si el uso de ENC en las mujeres durante las etapas críticas del embarazo y la lactancia supone o no un posible riesgo.

A genomic survey of transposable elements in the choanoflagellate Salpingoeca rosetta reveals selection on codon usage.

BACKGROUND: Unicellular species make up the majority of eukaryotic diversity, however most studies on transposable elements (TEs) have centred on multicellular host species. Such studies may have therefore provided a limited picture of how transposable elements evolve across eukaryotes. The choanoflagellates, as the sister group to Metazoa, are an important study group for investigating unicellular to multicellular transitions. A previous survey of the choanoflagellate Monosiga brevicollis revealed the presence of only three families of LTR retrotransposons, all of which appeared to be active. Salpingoeca rosetta is the second choanoflagellate to have its whole genome sequenced and provides further insight into the evolution and population biology of transposable elements in the closest relative of metazoans. RESULTS: Screening the genome revealed the presence of a minimum of 20 TE families. Seven of the annotated families are DNA transposons and the remaining 13 families are LTR retrotransposons. Evidence for two putative non-LTR retrotransposons was also uncovered, but full-length sequences could not be determined. Superfamily phylogenetic trees indicate that vertical inheritance and, in the case of one family, horizontal transfer have been involved in the evolution of the choanoflagellates TEs. Phylogenetic analyses of individual families highlight recent element activity in the genome, however six families did not show evidence of current transposition. The majority of families possess young insertions and the expression levels of TE genes vary by four orders of magnitude across families. In contrast to previous studies on TEs, the families present in S. rosetta show the signature of selection on codon usage, with families favouring codons that are adapted to the host translational machinery. Selection is stronger in LTR retrotransposons than DNA transposons, with highly expressed families showing stronger codon usage bias. Mutation pressure towards guanosine and cytosine also appears to contribute to TE codon usage. CONCLUSIONS: S. rosetta increases the known diversity of choanoflagellate TEs and the complement further highlights the role of horizontal gene transfer from prey species in choanoflagellate genome evolution. Unlike previously studied TEs, the S. rosetta families show evidence for selection on their codon usage, which is shown to act via translational efficiency and translational accuracy.

Identification of a mammalian silicon transporter.

Silicon (Si) has long been known to play a major physiological and structural role in certain organisms, including diatoms, sponges, and many higher plants, leading to the recent identification of multiple proteins responsible for Si transport in a range of algal and plant species. In mammals, despite several convincing studies suggesting that silicon is an important factor in bone development and connective tissue health, there is a critical lack of understanding about the biochemical pathways that enable Si homeostasis. Here we report the identification of a mammalian efflux Si transporter, namely Slc34a2 (also termed NaPiIIb), a known sodium-phosphate cotransporter, which was upregulated in rat kidney following chronic dietary Si deprivation. Normal rat renal epithelium demonstrated punctate expression of Slc34a2, and when the protein was heterologously expressed in Xenopus laevis oocytes, Si efflux activity (i.e., movement of Si out of cells) was induced and was quantitatively similar to that induced by the known plant Si transporter OsLsi2 in the same expression system. Interestingly, Si efflux appeared saturable over time, but it did not vary as a function of extracellular [Formula: see text] or Na+ concentration, suggesting that Slc34a2 harbors a functionally independent transport site for Si operating in the reverse direction to the site for phosphate. Indeed, in rats with dietary Si depletion-induced upregulation of transporter expression, there was increased urinary phosphate excretion. This is the first evidence of an active Si transport protein in mammals and points towards an important role for Si in vertebrates and explains interactions between dietary phosphate and silicon.

Aerotaxis in the closest relatives of animals.

As the closest unicellular relatives of animals, choanoflagellates serve as useful model organisms for understanding the evolution of animal multicellularity. An important factor in animal evolution was the increasing ocean oxygen levels in the Precambrian, which are thought to have influenced the emergence of complex multicellular life. As a first step in addressing these conditions, we study here the response of the colony-forming choanoflagellate Salpingoeca rosetta to oxygen gradients. Using a microfluidic device that allows spatio-temporal variations in oxygen concentrations, we report the discovery that S. rosetta displays positive aerotaxis. Analysis of the spatial population distributions provides evidence for logarithmic sensing of oxygen, which enhances sensing in low oxygen neighborhoods. Analysis of search strategy models on the experimental colony trajectories finds that choanoflagellate aerotaxis is consistent with stochastic navigation, the statistics of which are captured using an effective continuous version based on classical run-and-tumble chemotaxis.

The Evolution of Silicon Transport in Eukaryotes.

Biosilicification (the formation of biological structures from silica) occurs in diverse eukaryotic lineages, plays a major role in global biogeochemical cycles, and has significant biotechnological applications. Silicon (Si) uptake is crucial for biosilicification, yet the evolutionary history of the transporters involved remains poorly known. Recent evidence suggests that the SIT family of Si transporters, initially identified in diatoms, may be widely distributed, with an extended family of related transporters (SIT-Ls) present in some nonsilicified organisms. Here, we identify SITs and SIT-Ls in a range of eukaryotes, including major silicified lineages (radiolarians and chrysophytes) and also bacterial SIT-Ls. Our evidence suggests that the symmetrical 10-transmembrane-domain SIT structure has independently evolved multiple times via duplication and fusion of 5-transmembrane-domain SIT-Ls. We also identify a second gene family, similar to the active Si transporter Lsi2, that is broadly distributed amongst siliceous and nonsiliceous eukaryotes. Our analyses resolve a distinct group of Lsi2-like genes, including plant and diatom Si-responsive genes, and sequences unique to siliceous sponges and choanoflagellates. The SIT/SIT-L and Lsi2 transporter families likely contribute to biosilicification in diverse lineages, indicating an ancient role for Si transport in eukaryotes. We propose that these Si transporters may have arisen initially to prevent Si toxicity in the high Si Precambrian oceans, with subsequent biologically induced reductions in Si concentrations of Phanerozoic seas leading to widespread losses of SIT, SIT-L, and Lsi2-like genes in diverse lineages. Thus, the origin and diversification of two independent Si transporter families both drove and were driven by ancient ocean Si levels.

A model for the effects of germanium on silica biomineralization in choanoflagellates.

Silica biomineralization is a widespread phenomenon of major biotechnological interest. Modifying biosilica with substances like germanium (Ge) can confer useful new properties, although exposure to high levels of Ge disrupts normal biosilicification. No clear mechanism explains why this disruption occurs. Here, we study the effect of Ge on loricate choanoflagellates, a group of protists that construct a species-specific extracellular lorica from multiple siliceous costal strips. High Ge exposures were toxic, whereas lower Ge exposures produced cells with incomplete or absent loricae. These effects can be ameliorated by restoring the germanium : silicon ratio, as observed in other biosilicifying organisms. We developed simulations of how Ge interacts with polymerizing silica. In our models, Ge is readily incorporated at the ends of silica forming from silicic acid condensation, but this prevents further silica polymerization. Our 'Ge-capping' model is supported by observations from loricate choanoflagellates. Ge exposure terminates costal strip synthesis and lorica formation, resulting in disruption to cytokinesis and fatal build-up of silicic acid. Applying the Ge-capping model to other siliceous organisms explains the general toxicity of Ge and identifies potential protective responses in metalloid uptake and sensing. This can improve the design of new silica biomaterials, and further our understanding of silicon metabolism.

Motility of Colonial Choanoflagellates and the Statistics of Aggregate Random Walkers.

We illuminate the nature of the three-dimensional random walks of microorganisms composed of individual organisms adhered together. Such aggregate random walkers are typified by choanoflagellates, eukaryotes that are the closest living relatives of animals. In the colony-forming species Salpingoeca rosetta we show that the beating of each flagellum is stochastic and uncorrelated with others, and the vectorial sum of the flagellar propulsion manifests as stochastic helical swimming. A quantitative theory for these results is presented and species variability discussed.

A duplex PCR-based assay for measuring the amount of bacterial contamination in a nucleic acid extract from a culture of free-living protists.

BACKGROUND: Cultures of heterotrophic protists often require co-culturing with bacteria to act as a source of nutrition. Such cultures will contain varying levels of intrinsic bacterial contamination that can interfere with molecular research and cause problems with the collection of sufficient material for sequencing. Measuring the levels of bacterial contamination for the purposes of molecular biology research is non-trivial, and can be complicated by the presence of a diverse bacterial flora, or by differences in the relative nucleic acid yield per bacterial or eukaryotic cell. PRINCIPAL FINDINGS: Here we describe a duplex PCR-based assay that can be used to measure the levels of contamination from marine bacteria in a culture of loricate choanoflagellates. By comparison to a standard culture of known target sequence content, the assay can be used to quantify the relative proportions of bacterial and choanoflagellate material in DNA or RNA samples extracted from a culture. We apply the assay to compare methods of purifying choanoflagellate cultures prior to DNA extraction, to determine their effectiveness in reducing bacterial contamination. Together with measurements of the total nucleic acid concentration, the assay can then be used as the basis for determining the absolute amounts of choanoflagellate DNA or RNA present in a sample. CONCLUSIONS: The assay protocol we describe here is a simple and relatively inexpensive method of measuring contamination levels in nucleic acid samples. This provides a new way to establish quantification and purification protocols for molecular biology and genomics in novel heterotrophic protist species. Guidelines are provided to develop a similar protocol for use with any protistan culture. This assay method is recommended where qPCR equipment is unavailable, where qPCR is not viable because of the nature of the bacterial contamination or starting material, or where prior sequence information is insufficient to develop qPCR protocols.

A family of diatom-like silicon transporters in the siliceous loricate choanoflagellates.

Biosilicification is widespread across the eukaryotes and requires concentration of silicon in intracellular vesicles. Knowledge of the molecular mechanisms underlying this process remains limited, with unrelated silicon-transporting proteins found in the eukaryotic clades previously studied. Here, we report the identification of silicon transporter (SIT)-type genes from the siliceous loricate choanoflagellates Stephanoeca diplocostata and Diaphanoeca grandis. Until now, the SIT gene family has been identified only in diatoms and other siliceous stramenopiles, which are distantly related to choanoflagellates among the eukaryotes. This is the first evidence of similarity between SITs from different eukaryotic supergroups. Phylogenetic analysis indicates that choanoflagellate and stramenopile SITs form distinct monophyletic groups. The absence of putative SIT genes in any other eukaryotic groups, including non-siliceous choanoflagellates, leads us to propose that SIT genes underwent a lateral gene transfer event between stramenopiles and loricate choanoflagellates. We suggest that the incorporation of a foreign SIT gene into the stramenopile or choanoflagellate genome resulted in a major metabolic change: the acquisition of biomineralized silica structures. This hypothesis implies that biosilicification has evolved multiple times independently in the eukaryotes, and paves the way for a better understanding of the biochemical basis of silicon transport through identification of conserved sequence motifs.

Nitrile hydratase genes are present in multiple eukaryotic supergroups.

BACKGROUND: Nitrile hydratases are enzymes involved in the conversion of nitrile-containing compounds into ammonia and organic acids. Although they are widespread in prokaryotes, nitrile hydratases have only been reported in two eukaryotes: the choanoflagellate Monosiga brevicollis and the stramenopile Aureococcus anophagefferens. The nitrile hydratase gene in M. brevicollis was believed to have arisen by lateral gene transfer from a prokaryote, and is a fusion of beta and alpha nitrile hydratase subunits. Only the alpha subunit has been reported in A. anophagefferens. METHODOLOGY/PRINCIPAL FINDINGS: Here we report the detection of nitrile hydratase genes in five eukaryotic supergroups: opisthokonts, amoebozoa, archaeplastids, CCTH and SAR. Beta-alpha subunit fusion genes are found in the choanoflagellates, ichthyosporeans, apusozoans, haptophytes, rhizarians and stramenopiles, and potentially also in the amoebozoans. An individual alpha subunit is found in a dinoflagellate and an individual beta subunit is found in a haptophyte. Phylogenetic analyses recover a clade of eukaryotic-type nitrile hydratases in the Opisthokonta, Amoebozoa, SAR and CCTH; this is supported by analyses of introns and gene architecture. Two nitrile hydratase sequences from an animal and a plant resolve in the prokaryotic nitrile hydratase clade. CONCLUSIONS/SIGNIFICANCE: The evidence presented here demonstrates that nitrile hydratase genes are present in multiple eukaryotic supergroups, suggesting that a subunit fusion gene was present in the last common ancestor of all eukaryotes. The absence of nitrile hydratase from several sequenced species indicates that subunits were lost in multiple eukaryotic taxa. The presence of nitrile hydratases in many other eukaryotic groups is unresolved due to insufficient data and taxon sampling. The retention and expression of the gene in distantly related eukaryotic species suggests that it plays an important metabolic role. The novel family of eukaryotic nitrile hydratases presented in this paper represents a promising candidate for research into their molecular biology and possible biotechnological applications.