Cloning and expression of the engrailed.a gene of the barnacle Sacculina carcini

 Cirripedia (barnacles) constitute a crustacean monophyletic taxon which is very well defined by several synapomorphies. In particular, all cirripedes are composed of six thoracic segments, but are devoid of any complete abdominal segment. This body plan is preserved in the adult in non-parasitic groups, while the parasitic rhizocephalan cirripedes completely lose arthropodian segmentation at the adult stage. These traits make them a particularly favourable model for studying the formation and maintenance of segmental identity. For the above reasons, it seemed worthwhile to look at the segmentation gene engrailed in a cirripede. A complete engrailed.a cDNA was isolated from larvae of the rhizocephalan cirripede Sacculina carcini. Its expression was monitored during larval development by use of the monoclonal antibody MAb4D9 directed against the Drosophila homologous proteins. The Sacculina engrailed.a gene is expressed during the second and third larval stages in stripes within a posterior area corresponding to the presumptive trunk segments. Surprisingly, these stripes appear in a posterior to anterior sequence. Six engrailed.a stripes characterize the thoracic segments of the cirripedean ground plan. Received: 18 June 1998 / Accepted: 24 October 1998     

Tissue changes in the shore crab Carcinus maenas as a result of infection by the parasitic barnacle Sacculina carcini

We studied the effect of parasitic invasion by the barnacle Sacculina carcini on shore crabs Carcinus maenas collected from the Menai Straits in North Wales, UK. A significant reduction in serum protein and circulating granular, semi-granular and hyaline blood cells was observed in parasitised individuals, while serum ammonium and glucose concentrations were significantly increased. No difference in hepatopancreatic glycogen concentration was found between healthy and parasitised crabs. Histological analysis showed the apparent removal of fibrillar protein from infected muscle by the parasite. Hepatopancreas tubule necrosis was also routinely observed in infected individuals. Parasitisation by S. carcini dramatically affects the haemocyte population and serum chemistry of infected crabs.     

The Morphology of the Naupliar Stages of Sacculina carcini(Crustacea: Cirripedia: Rhizocephala)

A morphological study was carried out on the fournaupliar stages of Sacculina carciniusing mainly scanning electron microscopy. Frontal horns were present and throughout development the typical nauplius limbs remained simple and gnathobases were lacking. Such features are characteristic of other lecithotrophic barnacle nauplii. The presence of a vestigial ventral thoracic process was evident on the stage III nauplius and was even more prominent on the stage IV nauplius. These observations confirm that the rhizocephalan nauplius is close to the thoracican nauplius form and lend strong support for the retention of the Rhizocephala within the Cirripedia.     

The testis-specific expressed gene Spata34 is not required for fertility in mice

Molecular Biology Reports - It is estimated that more than two thousand genes exhibit testis-predominant expression pattern. The functions of hundreds of these genes have been explored during mouse...     

The effect of Sacculina carcini infections on the fouling, burying behaviour and condition of the shore crab, Carcinus maenas

Crabs infected by rhizocephalans usually do not moult. Because moulting is the ultimate defence against fouling epibionts, infected as opposed to uninfected crabs can be expected to harbour a diversity of hard-bottom organisms on their cuticula. Here we provide unequivocal evidence that this is the case in the Carcinus maenas-Sacculina carcini association. In a Danish sample of shore crabs, 75% of sacculinized individuals harboured macroscopic epibionts, whereas only 29% of the uninfected crabs were colonized. The mean numbers of fouling barnacles and serpulid tubeworms per individual were 7.7 and 47.3 for uninfected and infected crabs, respectively, corresponding to coverage of the cuticula by 0.7 and 5.4%. Infected crabs were 12% lower in tissue dry weight than uninfected individuals, which may be a factor causing the moult of sacculinized crabs to be postponed. Finally, a laboratory experiment suggested that infected crabs are less likely to bury than uninfected specimens. Because burying is an important fouling defence, such a parasite-induced behavioural change will favour the colonization by epibionts. It is argued that rhizocephalans infecting crabs from soft-bottom communities may indirectly affect the structure of the free-living benthic community by adding hard-bottom species that otherwise would be absent.     

VITO-1, a novel vestigial related protein is predominantly expressed in the skeletal muscle lineage

In order to identify novel genes expressed in skeletal muscle we performed a subtractive hybridization for genes expressed in human skeletal muscle but not in other tissues. We identified a novel scalloped interaction domain (SID) containing protein in humans and in the mouse, which we named VITO-1. Highest homology of VITO-1 was found with the Drosophila vestigial and the human TONDU proteins in the SID (54 and 40%, respectively). Using whole-mount hybridzation and Northern blot analysis, we showed that VITO-1 is expressed in the somitic myotome from E8.75 mouse embryos onwards and later on in skeletal muscle but not in the heart. Additional expression domains during development were detected in the pharyngeal pouches and clefts starting at E8.0 as well as in the cranial pharynx and in Rathkes pouch. By Northern blot analysis, we found VITO-1 to be up-regulated in C2C12 myotubes although some expression can be detected in proliferating C2C12 myoblasts. No expression was spotted in other adult mouse tissues. Likewise, expression of human Vito-1 during fetal and adult human development was found exclusively in skeletal muscle preferentially in fast skeletal muscles. These data suggest a role of VITO-1 for the development of skeletal muscles and of pharyngeal clefts/Rathkes' pouch derived structures.     

VITO-1, a novel vestigial related protein is predominantly expressed in the skeletal muscle lineage

In order to identify novel genes expressed in skeletal muscle we performed a subtractive hybridization for genes expressed in human skeletal muscle but not in other tissues. We identified a novel scalloped interaction domain (SID) containing protein in humans and in the mouse, which we named VITO-1. Highest homology of VITO-1 was found with the Drosophila vestigial and the human TONDU proteins in the SID (54 and 40%, respectively). Using whole-mount hybridzation and Northern blot analysis, we showed that VITO-1 is expressed in the somitic myotome from E8.75 mouse embryos onwards and later on in skeletal muscle but not in the heart. Additional expression domains during development were detected in the pharyngeal pouches and clefts starting at E8.0 as well as in the cranial pharynx and in Rathkes pouch. By Northern blot analysis, we found VITO-1 to be up-regulated in C2C12 myotubes although some expression can be detected in proliferating C2C12 myoblasts. No expression was spotted in other adult mouse tissues. Likewise, expression of human Vito-1 during fetal and adult human development was found exclusively in skeletal muscle preferentially in fast skeletal muscles. These data suggest a role of VITO-1 for the development of skeletal muscles and of pharyngeal clefts/Rathkes' pouch derived structures.     

Zebrafish keratin 8 is expressed at high levels in the epidermis of regenerating caudal fin

Cytokeratins are structural proteins of the intermediate filament family and are mainly expressed in epithelial cells. In several vertebrates it has been shown that keratin 8 is expressed in simple epithelial tissues, some non-epithelial tissue and in hyper-proliferative tissues during development and tumor transformation. We previously cloned and characterised the zebrafish (Danio rerio) homologous cytokeratin 8 cDNA (zfk8) which was described as an epidermal marker during zebrafish development. It has been found that the zfk8 gene is normally expressed in simple epithelia in embryonic and mature zebrafish. Using whole-mount in situ hybridisation, we show in this report that expression of zfk8 is tightly linked to the regeneration of caudal fin and exclusively observed in epidermal cells. It is strongly expressed in the epidermis overlaying the inter-rays zone of regenerating caudal fin. Our results indicate that in zebrafish, cytokeratin 8 is a suitable epidermal marker during regeneration.     

On the fine structure of the regressing ecdysial glands of Carcinus maenas L. (Crustacea decapoda) parasitized by Sacculina carcini thompson

Summary The ecdysial glands (Y organs) of the crab Carcinus maenas regress in the presence of an external parasite, Sacculina carcini. This regression is more or less severe and may lead to complete autolysis. Three gradual stages in this involutionary process are described. In stage I, the gland cells are nearly normal. Nuclei and cytoplasmic organelles remain unchanged, but large vacuoles begin to appear. Stage II corresponds to more or less drastic nuclear pyknosis and cytoplasmic alterations. Myelin figures are large and numerous. Lysosomes and autophagic vacuoles with phosphatase activity are abundant. However, the general cellular architecture remains preserved. Stage III corresponds to irreversible cytolysis; nuclear envelopes and plasma membranes have disappeared. What remains is an accumulation of cellular debris becoming engulfed by circulating hemocytes. Not all of the gland cells of any given Y organ show the same degree of regression; degeneration is asynchronous.Structures seemingly corresponding to absorptive roots of the parasite are seen. Their lumen is coated with microvilli. The putative direct and indirect influences of the rhizocephalan parasite on its host are discussed. Our results on regressing Y organs of parasitized crabs are compared with those on regressing ecdysial glands of insects.Dedicated to the memory of Sir Francis Knowles, the first investigator to examine the ultrastructure of the Y organ of Carcinus maenas We wish to express our thanks to Professor Berta Scharrer for her critical advice     

The amphioxus FoxQ1 gene is expressed in the developing endostyle

The FoxQ1 genes form a distinct group within the Fox (also known as forkhead) gene family. We have isolated a gene from the amphioxus Branchiostoma floridae that encodes a forkhead domain with high identity to FoxQ1 genes in other chordates. Molecular phylogenetic analysis places AmphiFoxQ1 in a robust grouping with vertebrate FoxQ1 genes and with Ciona intestinalis Ci-FoxQ1. This group is separate from that containing AmphiFoxQ2, which instead groups with other invertebrate Fox genes. The expression of AmphiFoxQ1 was analysed by whole mount in situ hybridisation. The results show that AmphiFoxQ1 expression is confined to the developing endoderm, and specifically marks the endostyle and associated peripharyngeal bands of amphioxus larvae. Ci-FoxQ1 is also expressed in the endostyle, highlighting this as a conserved site of FoxQ1 gene expression in basal chordates.     

The expression of a highly expressed Bacillus subtilis gene is not reduced by introduction of multiple codons normally not present in such genes

A recombinant DNA Proteus mirabilis L-form expression system, LVI (pJS127), was used to synthesize human fusion interferon alpha 1 (f-IFN-alpha 1). In the expression plasmid used, the complete coding sequence of IFN-alpha 1 was linked to the streptococcal speA promoter and the 5' end of the speA structural gene including its signal sequence coding region. LVI (pJS127) was capable of complete secretion into the culture medium of biologically active f-IFN-alpha 1 whose identity was confirmed by immunological and chemical evidence. In particular, bacterial L-forms were for the first time shown to be capable of correct signal peptide processing, as determined by N-terminal sequencing of the secreted f-IFN.