The epidemiology and public health importance of toxocariasis: A zoonosis of global importance

Toxocariasis, caused by infection with larvae of Toxocara canis, and to a lesser extent by Toxocara cati and other ascaridoid species, manifests in humans in a range of clinical syndromes. These include visceral and ocular larva migrans, neurotoxocariasis and covert or common toxocariasis. Toxocara canis is one of the most widespread public health and economically important zoonotic parasitic infections humans share with dogs, cats and wild canids, particularly foxes. This neglected disease has been shown through seroprevalence studies to be especially prevalent among children from socio-economically disadvantaged populations both in the tropics and sub-tropics and in industrialised nations. Human infection occurs by the accidental ingestion of embryonated eggs or larvae from a range of wild and domestic paratenic hosts. Most infections remain asymptomatic. Clinically overt infections may go undiagnosed, as diagnostic tests are expensive and can require serological, molecular and/or imaging tests, which may not be affordable or available. Treatment in humans varies according to symptoms and location of the larvae. Anthelmintics, including albendazole, thiabendazole and mebendazole may be given together with anti-inflammatory corticosteroids. The development of molecular tools should lead to new and improved strategies for the treatment, diagnosis and control of toxocariasis and the role of other ascaridoid species in the epidemiology of Toxocara spp. Molecular technologies may also help to reveal the public health importance of T. canis, providing new evidence to support the implementation of national control initiatives which have yet to be developed for Toxocara spp. A number of countries have implemented reproductive control programs in owned and stray dogs to reduce the number of young dogs in the population. These programs would positively impact upon T. canis transmission since the parasite is most fecund and prevalent in puppies. Other control measures for T. canis include the regular and frequent anthelmintic treatment of dogs and cats, starting at an early age, education and enforcement of laws for the disposal of canine faeces, dog legislation and personal hygiene. The existence of wild definitive and paratenic hosts complicates the control of T. canis. Increasing human and dog populations, population movements and climate change will all serve to increase the importance of this zoonosis. This review examines the transmission, diagnosis and clinical syndromes of toxocariasis, its public health importance, epidemiology, control and current research needs.     

Preliminary analysis of geographical distribution based on cold hardiness for Evergestis extimalis (Scopoli) (Lepidoptera: Pyralidae) on Qinghai–Tibet Plateau

Evergestis extimalis  (Scopoli) is a pest insect present in spring rape fields of the Qinghai–Tibet plateau. A survey of its distribution and analysis of its physiological and biochemical variances of its overwintering larvae were conducted in this study. Prior to 2006, Evergestis extimalis Scopli appeared only sporadically at the east agricultural district of Qinghai Province at 2,100 m elevation; after 2006, there have been frequent outbreaks at 2,200 m or so height. The insect's distribution has extended continuously toward higher altitudes yearly, and the scope of its damage reached 2,800 m height in 2010. These changes indicate that the cold hardiness of E. extimalis is on the rise. Physiological and biochemical analyses were performed for the insect's overwintering larvae from November 2011 to March 2012. The supercooling point (SCP) and freezing point (FP) ranged from ?6.85°C to ?12.49°C and from ?6.23°C to ?8.17°C, respectively, and both were at their respective lowest points in January 2012; the lowest points of water and fat contents (which did not vary to any extreme degree throughout the test period) were also observed in January 2012. Glycogen content varied from 2.42 mg/g to 4.56 mg/g. Protein content increased gradually at the first two months and reached its peak in January 2012 before dropping slightly. The activity of protective enzymes POD, CAT, and SOD varied with changes in environmental temperature, and each was at its lowest point in January 2012. With the exception of protein and glycerol content, other physiological and biochemical variances were generally parallel with environmental temperature, strongly indicating that E. extimalis has indeed developed cold hardiness.     

Comparative analysis of metabolome of rice seeds at three developmental stages using a recombinant inbred line population

Plants are considered an important food and nutrition source for humans. Despite advances in plant seed metabolomics, knowledge about the genetic and molecular bases of rice seed metabolomes at different developmental stages is still limited. Here, using Zhenshan 97 (ZS97) and Minghui 63 (MH63), we performed a widely targeted metabolic profiling in seeds during grain filling, mature seeds and germinating seeds. The diversity between MH63 and ZS97 was characterized in terms of the content of metabolites and the metabolic shifting across developmental stages. Taking advantage of the ultra‐high‐density genetic map of a population of 210 recombinant inbred lines (RILs) derived from a cross between ZS97 and MH63, we identified 4681 putative metabolic quantitative trait loci (mQTLs) in seeds across the three stages. Further analysis of the mQTLs for the codetected metabolites across the three stages revealed that the genetic regulation of metabolite accumulation was closely related to developmental stage. Using in silico analyses, we characterized 35 candidate genes responsible for 30 structurally identified or annotated compounds, among which LOC_Os07g04970 and LOC_Os06g03990 were identified to be responsible for feruloylserotonin and l ‐asparagine content variation across populations, respectively. Metabolite?agronomic trait association and colocation between mQTLs and phenotypic quantitative trait loci (pQTLs) revealed the complexity of the metabolite?agronomic trait relationship and the corresponding genetic basis.     

Trichinella spiralis: strong antibody response to a 49 kDa newborn larva antigen in infected rats

In this work, we analyzed the kinetics of anti-Trichinella spiralis newborn larva (NBL) antibodies (Ab) and the antigenic recognition pattern of NBL proteins and its dose effects. Wistar rats were infected with 0, 700, 2000, 4000 and 8000 muscle larvae (ML) and bled at different time intervals up to day 31 post infection (p.i.). Ab production was higher with 2000 ML dose and decreased with 8000, 4000 and 700 ML. Abs were not detected until day 10, peaked on day 14 for the 2000 ML dose and on day 19 for the other doses and thereafter declined slowly from 19 to 31 days p.i. In contrast, Abs to ML increased from day 10, peaked on day 19 and remained high until the end of the study. Abs bound strongly at least to three NBL components of 188, 205 and 49 kDa. NBL antigen of 188 and 205 kDa were recognized 10-26 days p.i. and that of 49 kDa from day 10 to day 31 p.i. A weak recognition towards antigens of 52, 54, 62 and 83 kDa was also observed during the infection. An early recognition of 31, 43, 45, 55, 68 and 85 kDa ML antigens was observed whereas the response to those of 43, 45, 48, 60, 64 and 97 kDa (described previously as TSL-1 antigens) occurred late in the infection. A follow-up of antigen recognition up to day 61 with the optimal immunization dose (2000 ML) evidenced a decline of Ab production to the 49 kDa NBL antigen 42 days p.i., which suggested antigenic differences with the previously reported 43 kDa ML antigen strongly recognized late in the infection. To analyze the stage-specificity of the 49 kDa NBL antigen, polyclonal antibodies (PoAb) were obtained in rats immunized with 49 kDa NBL antigen. PoAb reacted strongly with the 49 kDa NBL component in NBL total soluble extract but no reactivity was observed with soluble antigen of the other T. spiralis stages. Albeit with less intensity, the 49 kDa component was also recognized by PoAb together with other antigens of 53, 97 and 107 kDa, in NBL excretory-secretory products (NBL-ESP). Thus, our results reveal differences in the kinetics of anti-NBL and ML Ab responses. While anti-NBL Abs declined slowly from day 19 until the end of the experiment, Abs to ML antigen remained high in the same period. It is remarkable the optimal Ab response to NBL antigens with 2000 ML infective dose and the reduced number of NBL antigens identified throughout the experimental T. spiralis infection, standing out the immunodominant 49 kDa antigen. Interestingly, this antigen, which was prominently expressed in NBL somatic proteins, was also detected in NBL-ESP.     

Gene co-expression network analysis for identifying genetic markers in Parkinson's disease - a three-way comparative approach

Parkinson's disease (PD) is a neurodegenerative disorder involving progressive deterioration of dopaminergic neurons. Although few genetic markers for familial PD are known, the etiology of sporadic PD remains poorly understood. Microarray data was analysed for induced pluripotent stem cells (iPSCs) derived from PD patients and mature neuronal cells (mDA) differentiated from these iPSCs. Combining expression and semantic similarity, a highly-correlated PD interactome was constructed that included interactions of established Parkinson's disease marker genes. A novel three-way comparative approach was employed, delineating topologically and functionally important genes. These genes showed involvement in pathways like Parkin-ubiquitin proteosomal system (UPS), immune associated biological processes and apoptosis. Of interest are three genes, eEF1A1, CASK, and PSMD6 that are linked to PARK2 activity in the cell and thereby form attractive candidate genes for understanding PD. Network biology approach delineated in this study can be applied to other neurodegenerative disorders for identification of important genetic regulators.     

Novel protein from larval sponge cells,ilborin, is related to energy turnover and calcium binding and is conserved among marine invertebrates

Sponges (phylum Porifera) are early-branching animals, whose outwardly simple body plan is underlain by a complex genetic repertoire. The transition from a mobile larva to an attached filter-feeding organism occurs by metamorphosis, a process accompanied by a radical change of the body plan and cell transdifferentiation. The continuity between larval cells and adult tissues is still obscure. In a previous study, we have produced polyclonal antibodies against the major protein of the flagellated cells covering the larva of the sponge Halisarca dujardini, used them to trace the fate of these cells and shown that the larval flagellated cells transdifferentiate into the choanocytes. In the present work, we identified the sequence of this novel protein, which we named ilborin. A search in the open databases showed that multiple orthologues of the newly identified protein are present in sponges, cnidarians, flatworms, ctenophores and echinoderms, but none of them has been described yet. Ilborin has two conserved domains: triosephosphate isomerase-barrel, which has enzymatic activity against macroergic compounds, and canonical EF-hand, which binds calcium. mRNA of ilborin is expressed in the larval flagellated cells. We suggest that the new protein is involved in the calcium-mediated regulation of energy metabolism, whose activation precedes metamorphosis.     

Effets du retard dans la première alimentation sur le développement de la larve planctotrophe de l'oursin Paracentrotus lividus

The growth of the skleleton and changes in biochemical constituents (proteins, carbohydrates and lipids) were observed in embryos (days 0 and 1) and larvae (2-8 days) of the sea urchin Paracentrotus lividus that were starved (C 0) or fed low (1,000 cells of Hymenomonas elongata, C 1) or high (5,000 cells, C 5). Different batches of C 1 and C 5 larvae were fed first the 2nd, 3rd, 4th or 5th day after fertilization. Initiation of feeding 24 h after hatching slowed down the rate of increase in length of the larval appendages. A differential growth of skeletic rods (somatic and postoral rods) and variations in proteins weights shows the existence of a mixotrophic phase between endotrophic and planktotrophic phases. Best development occured in larvae which were first fed at the lower food level 24 h after hatching. On the 2nd and the 3rd day the somatic/postoral rod ratio is ≥1. This higher ration can be used to estimate the age of natural populations of larvae.     

Alternative Ways to Become a Juvenile or a Definitive Phenotype (and on Some Persisting Linguistic Offenses)

Lack of knowledge of early and juvenile development often makes it difficult to decide when a fish becomes a juvenile or, for that matter, a definitive phenotype. According to the established life-history model, a fish develops naturally in a saltatory manner, its entire life consisting of a sequence of stabilized self-organizing steps, separated by distinct less stabilized thresholds. Changes are usually introduced during thresholds. In principle, there are two ways to reach the juvenile period: by indirect or by direct development. Indirectly developing fishes have a distinct larva period that ends in a cataclysmic or mild remodeling process, called metamorphosis, from which the fishes emerge as juveniles. During metamorphosis, most temporary organs and structures of the embryos and larvae are replaced by definitive organs and structures that are also possessed by the adults. In contrast, directly developing fishes have no larvae. Their embryos develop directly into juveniles and do not need major remodeling. Consequently, the beginning of their juvenile period is morphologically and functionally less distinct than in indirect development. The life-history model helps to find criteria that identify the natural boundaries between the different periods in the life of a fish, among them, the beginning of the juvenile period. Looking at it from a different angle, when ontogeny progresses from small eggs with little yolk, larvae are required as the necessary providers of additional nutrients (feeding entities similar to amphibian tadpoles or butterfly caterpillars) in order to accumulate materials for the metamorphosis into the definitive phenotypes. Directly developing fishes start with large demersal eggs provided with an adequate volume of high density yolk and so require no or little external nutrients to develop into the definitive phenotype. These large eggs are released and develop in concentrated clutches. It therefore becomes possible and highly effective to guard them in nests or bear them in external pouches, gill chambers or the buccal cavity. Viviparity is the next natural step. Now the maternal investment into large yolks can be supplemented or replaced by direct food supply to the developing embryos like, for example, the secretion of uterine histotrophe or nutrient transfer via placental analogues. When the young of guarders and bearers start exogenous feeding, they are much larger or better developed than larvae of nonguarders and the larva period in the former is reduced to a vestige or eliminated entirely. In the latter case, the juvenile period begins with the first exogenous feeding. Such precocial fishes are more specialized and able to survive better in competitive environments. In contrast, altricial forms retain or revert to a life-history style with indirect development and high fecundity when dispersal is advantageous or essential. Fishes become juveniles when the definitive phenotype is formed in most structures, either indirectly from a larva via metamorphosis or directly from the embryo.