Saturnius minutus n. sp. and S. dimitrovi n. sp. (Digenea: Hemiuridae) from Mugil cephalus L. (Teleostei: Mugilidae), with a multivariate morphological analysis of the Mediterranean species of Saturnius Manter, 1969

Three species of the bunocotyline genus Saturnius Manter, 1969 are described from the stomach lining of mugilid fishes of the Mediterranean and Black Seas. Two of the species are new: S. minutus n. sp. occurs in Mugil cephalus off the Mediterranean coast of Spain; and S. dimitrovi n. sp., a parasite of M. cephalus off the Bulgarian Black Sea coast and the Spanish Mediterranean coast, was originally described as S. papernai by Dimitrov et al. (1998). In addition, S. papernai Overstreet, 1977 is redescribed from M. cephalus off the Spanish Mediterranean coast and from Liza aurata and L. saliens off the Bulgarian Black Sea coast. The three species are distinguished morphometrically using univariate and multivariate analyses. These results were verified using Linear Discriminant Analysis which correctly allocated all specimens to their species designations based on morphology (i.e. 100% successful classification rate) and assigned almost all specimens to the correct population (locality). The following variables were selected for optimal separation between samples: the length of the forebody, ventral sucker and posterior testis, the length and width of the posteriormost pseudosegment, and the width of the muscular flange at ventral sucker level.     

Phylogenetic screening of the human genome: identification of differentially hybridizing repetitive sequence families

The phi-screen, a method of phylogenetic screening, can be employed to detect repetitive sequence families that differentially hybridize between closely related species. Such differences may involve sequence divergence or variations in copy number, including total presence versus absence of a family of repeated DNA. We present the results of a phi-screen comparing the human genome to that of the prosimian, Galago crassicaudatus. Three human repetitive families that are divergent or not present in galago have been detected. One of these families is described in detail; it is similar among the anthropoids but is present in a lower copy number and/or divergent form in prosimians. The family is clearly related to the transposon-like human element (THE) described by Paulson et al. (1985). THEs have long terminal repeats reminiscent of retroviruses but are unique in that they have no sequence similarity to known mammalian retroviruses. The sequence of a solo long terminal repeat, found unassociated with THE internal sequence, is presented. This family member, THE p2, is bordered by a 5-bp target-site repeat and is interrupted by the insertion of an Alu element. A solo THE element sequenced by Wiginton et al. (1986) contains an insertion of Alu at precisely the same position as does THE p2.      

Functional studies of signaling pathways in peri-implantation development of the mouse embryo by RNAi

Background

Studies of gene function in the mouse have relied mainly on gene targeting via homologous recombination. However, this approach is difficult to apply in specific windows of time, and to simultaneously knock-down multiple genes. Here we report an efficient method for dsRNA-mediated gene silencing in late cleavage-stage mouse embryos that permits examination of phenotypes at post-implantation stages.

Results

We show that introduction of Bmp4 dsRNA into intact blastocysts by electroporation recapitulates the genetic Bmp4 null phenotype at gastrulation. It also reveals a novel role for Bmp4 in the regulation the anterior visceral endoderm specific gene expression and its positioning. We also show that RNAi can be used to simultaneously target several genes. When applied to the three murine isoforms of Dishevelled, it leads to earlier defects than previously observed in double knock-outs. These include severe delays in post-implantation development and defects in the anterior midline and neural folds at headfold stages.

Conclusion

Our results indicate that the BMP4 signalling pathway contributes to the development of the anterior visceral endoderm, and reveal an early functional redundancy between the products of the murine Dishevelled genes. The proposed approach constitutes a powerful tool to screen the functions of genes that govern the development of the mouse embryo.     

Girdles as the main infection site for Paradeontacylix kampachi (Sanguinicolidae) in the greater amberjack Seriola dumerili

In this study, we provide new information about the habitats selected by the blood fluke Paradeontacylix kampachi in the greater amberjack Seriola dumerili based on an exhaustive anatomical examination. From May to October 1998, 21 fish of the 0+ age class were collected from tanks of the Spanish Institute of Oceanography in Puerto de Mazarrón, Spain, for parasitological analysis. Individuals of P. kampachi were found in 17 of the 21 fish analysed (mean intensity +/- SD: 13.6 +/- 16.6; median: 6). Worms occurred in the girdles, cephalic kidney, sinus venosus, kidney and branchial arteries. A Friedman test with a post-hoc contrast revealed a significantly higher number of worms in the girdles when compared with the other sites, suggesting this may be the main habitat for P. kampachi. This location had never been reported as a habitat for any species of Paradeontacylix, probably because it had not been examined before. Girdles should be routinely examined to estimate the actual intensity of infection and to maximize the likelihood of finding this species of digenean.     

Patterns of trunk spine growth in two congeneric species of acanthocephalan: investment in attachment may differ between sexes and species

Acanthocephalans have evolved a hooked proboscis and some taxa have trunk spines to attach to their definitive hosts. These structures are generated before being used, thus a key question is how investment in attachment could optimally be allocated through the ontogeny. The number and arrangement of hooks and spines are never modified in the definitive host, but it is unclear whether these structures grow during adult development. A comparison of the size of trunk spines between cystacanths and adults of Corynosoma cetaceum and C. australe indicated that spines grow in both species, but only in females, which also had significantly larger spines than males. This sexual dimorphism did not result from pure allometry because the body of females was smaller, and did not grow more than that of males. However, having a longer lifespan, females would need to withstand the extreme flow conditions prevailing in marine mammals for longer, inducing different investment and development schedules for spines. Patterns of spine growth also differed between species: fore-trunk spines grew in both species, but hind-trunk spines did only in C. cetaceum. In conclusion, investment strategies on attachment may differ, not only between congeneric species of acanthocephalan, but also between sexes of the same species.     

Dp71Δ78‐79 dystrophin mutant stimulates neurite outgrowth in PC12 cells via upregulation and phosphorylation of HspB1

PC12 cells acquire a neuronal phenotype in response to nerve growth factor (NGF). However, this phenotype is more efficiently achieved when the Dp71Δ_78‐79 dystrophin mutant is stably expressed in PC12‐C11 cells. To investigate the effect of Dp71Δ_78‐79 overexpression on the protein profile of PC12‐C11 cells, we compared the expression profiles of undifferentiated and NGF‐differentiated PC12‐C11 and PC12 cells by 2DE. In undifferentiated cultures, one protein was downregulated, and five were upregulated. Dp71Δ_78‐79 overexpression had a greater effect on differentiated cultures, with ten proteins downregulated and seven upregulated. The protein with the highest upregulation was HspB1. Changes in HspB1 expression were validated by Western blot and immunofluorescence analyses. Interestingly, the neurite outgrowth in PC12‐C11 cells was affected by a polyclonal antibody against HspB1, and the level of HspB1 and HspB1Ser86 decreased, suggesting an important role for this protein in this cellular process. Our results show that Dp71Δ_78‐79 affects the expression level of some proteins and that the stimulated neurite outgrowth produced by this mutant is mainly through upregulation and phosphorylation of HspB1.     

Effect of deletion and overexpression of tryptophan metabolism genes on growth and fermentation capacity at low temperature in wine yeast

Low‐temperature fermentations produce wines with greater aromatic complexity, but the success of these fermentations greatly depends on the adaptation of yeast cells to cold. Tryptophan has been previously reported to be a limiting amino acid during Saccharomyces cerevisiae growth at low temperature. The objective of this study was to determine the influence of the tryptophan metabolism on growth and fermentation performance during low‐temperature wine fermentation. To this end, we constructed the deletion mutants of the TRP1 and TAT2 genes in a derivative haploid of a commercial wine strain, and the TAT2 gene was overexpressed in the prototroph and auxotroph (Δtrp1) backgrounds. Then we characterized growth and fermentation activity during wine fermentation at low and optimum temperatures. Our results partially support the role of this amino acid in cold yeast growth. Although deletion of TRP1 impaired amino acid uptake and the growth rate at low temperature in synthetic must, this growth impairment did not affect the fermentation rate. Deletion of TAT2 endorsed this strain with the highest nitrogen consumption capacity and the greatest fermentation activity at low temperature. Our results also evidenced reduced ammonium consumption in all the strains at low temperature. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:776–783, 2014