Feeding of the Cymatiid Gastropod, Argobuccinum argus, in Relation to the Structure of the Proboscis and Secretions of the Proboscis Gland

Several gastropod families belonging to the superfamily Tonnaceaare known to bore into the calcareous shells of echinoids andbivalves, but little work has been done on the family Cymatiidae.New observations show that the cymatiid, Argobuccinum argus,which feeds on the tubicolous polychaete, Gunnarea capensis,possesses large proboscis glands which secrete 0.4 to 0.5N H₂SO₄;further, the secretion dissolves greater amounts of pure CaCO₃than does O.47N H₂SO₄, alone. A toxin is also present, whichabolishes responses to light and touch in several invertebrates. The proboscis is atypically pleurembolic, having a permanentproboscis sheath. Retraction is due to the muscles ot the probosciswall, and the contracted proboscis is not inverted. Unlike othermesogastropods, the Tonnacea have three pairs ofglands associatedwith the foregut: proboscis glands, true salivary glands, anda small, partly paired gland of unknown function immediatelyposterior to the buccal mass. It is concluded that because of an abundance of readily availablefood in the form of Gunnarea, A. argus does not drillinto animalsprotected by a calcareous shell. The presence of a CaCO₃ dissolvingmechanism indicates that the Cymatiidae ingeneral may be ableto employ this method of feeding.     

Male polymorphism in some Old World species of Cryptocheilus Panzer (Hymenoptera: Pompilidae)

The hypothesis that males of certain species of the pompilid genus Cryptocheilus Panzer are polymorphic, first proposed by H. Wolf, is examined critically in the light of modern knowledge of the mating systems of Hymenoptera and the known biology of Cryptocheilus species. Speculations are made as to the likely selection pressures operating to produce this phenomenon; nine Old World species of Cryptocheilus are identified as probable examples. The taxonomic implications of the hypothesis are considered; one new generic and nine new specific synonymies are listed, and lectotypes are designated for three nominal species. Two names are retrieved from synonymy for species here recognized as valid. A key is provided for the extreme forms of the males of these species; more detailed treatment must await full revision of Cryptocheilus.     

Chemoprevention of rat liver toxicity and carcinogenesis by Spirulina

Spirulina platensis (SP) is a filamentous cyanobacterium microalgae with potent dietary phyto-antioxidant, anti-inflammatory and anti-cancerous properties. The present study aimed to investigate the chemopreventive effect of SP against rat liver toxicity and carcinogenesis induced by dibutyl nitrosamine (DBN) precursors, and further characterized its underlying mechanisms of action in HepG2 cell line. Investigation by light and electron microscopy showed that DBN treatment induced severe liver injury and histopathological abnormalities, which were prevented by SP supplementation. The incidence of liver tumors was significantly reduced from 80 to 20% by SP. Immunohistochemical results indicated that both PCNA and p53 were highly expressed in the liver of DBN-treated rats, but were significantly reduced by SP supplementation. Molecular analysis indicated that SP treatment inhibited cell proliferation, which was accompanied by increased p21 and decreased Rb expression levels at 48hrs post-treatment. In addition, SP increased Bax and decreased Bcl-2 expression, indicating induction of apoptosis by 48hrs. This is the first report of the in vivo chemopreventive effect of SP against DBN-induced rat liver cytotoxicity and carcinogenesis, suggesting its potential use in chemoprevention of cancer.     

The approximate entropy of the electromyographic signals of tremor correlates with the osmotic fragility of human erythrocytes

Background  

The main problem of tremor is the damage caused to the quality of the life of patients, especially those at more advanced ages. There is not a consensus yet about the origins of this disorder, but it can be examined in the correlations between the biological signs of aging and the tremor characteristics.     

Comparative neuroanatomy suggests repeated reduction of neuroarchitectural complexity in Annelida

Background

Paired mushroom bodies, an unpaired central complex, and bilaterally arranged clusters of olfactory glomeruli are among the most distinctive components of arthropod neuroarchitecture. Mushroom body neuropils, unpaired midline neuropils, and olfactory glomeruli also occur in the brains of some polychaete annelids, showing varying degrees of morphological similarity to their arthropod counterparts. Attempts to elucidate the evolutionary origin of these neuropils and to deduce an ancestral ground pattern of annelid cerebral complexity are impeded by the incomplete knowledge of annelid phylogeny and by a lack of comparative neuroanatomical data for this group. The present account aims to provide new morphological data for a broad range of annelid taxa in order to trace the occurrence and variability of higher brain centers in segmented worms.

Results

Immunohistochemically stained preparations provide comparative neuroanatomical data for representatives from 22 annelid species. The most prominent neuropil structures to be encountered in the annelid brain are the paired mushroom bodies that occur in a number of polychaete taxa. Mushroom bodies can in some cases be demonstrated to be closely associated with clusters of spheroid neuropils reminiscent of arthropod olfactory glomeruli. Less distinctive subcompartments of the annelid brain are unpaired midline neuropils that bear a remote resemblance to similar components in the arthropod brain. The occurrence of higher brain centers such as mushroom bodies, olfactory glomeruli, and unpaired midline neuropils seems to be restricted to errant polychaetes.

Conclusions

The implications of an assumed homology between annelid and arthropod mushroom bodies are discussed in light of the 'new animal phylogeny'. It is concluded that the apparent homology of mushroom bodies in distantly related groups has to be interpreted as a plesiomorphy, pointing towards a considerably complex neuroarchitecture inherited from the last common ancestor, Urbilateria. Within the annelid radiation, the lack of mushroom bodies in certain groups is explained by widespread secondary reductions owing to selective pressures unfavorable for the differentiation of elaborate brains. Evolutionary pathways of mushroom body neuropils in errant polychaetes remain enigmatic.     

Male polymorphism in some Old World species of Cryptocheilus Panzer (Hymenoptera: Pompilidae)

The hypothesis that males of certain species of the pompilid genus Cryptocheilus Panzer are polymorphic, first proposed by H. Wolf, is examined critically in the light of modern knowledge of the mating systems of Hymenoptera and the known biology of Cryptocheilus species. Speculations are made as to the likely selection pressures operating to produce this phenomenon; nine Old World species of Cryptocheilus are identified as probable examples. The taxonomic implications of the hypothesis are considered; one new generic and nine new specific synonymies are listed, and lectotypes are designated for three nominal species. Two names are retrieved from synonymy for species here recognized as valid. A key is provided for the extreme forms of the males of these species; more detailed treatment must await full revision of Cryptocheilus.     

Allozyme differentiation of populations of the dogwhelk Nucella lapillus, (L.): the relative effects of geographic distance and variation in chromosome number

Geographic patterns of genie differentiation were compared with differentiation between karyotypes in the intertidal snail Nucella lapillus. Samples from 24 sites covering the species range in Europe and North America were analysed for allozyme variation at 16 soluble enzyme loci. Two homokaryotypes have been identified with diploid numbers 2n = 26 and 2n= 36 (variation is Robertsonian and hybrids have intermediate chromosome numbers) and samples were classified (on the basis of published data) according to karyotype. Group 1 consisted of samples from three English Channel populations of higher chromosome number (on average 2n > 32) and Group 2 consisted of the remaining 21 samples (presumed to be 2n= 26). Karyotype variation accounts for roughly the same amount of the absolute allozyme variance as geographic variation (46.3 °, and 53.7°, respectively). Yet the patterns of differentiation seen between karyotypes and with geographic separation are very different. In samples classified as 2n= 26 (Group 2), while there is a significant amount of heterogeneity (F_ST per locus averaged 0.128 for 10 polymorphic loci), allozyme variation occurs independently at different loci so mean genetic identity (Nei) is high: 0.972. There is only a slight decline in genetic identity with distance (genetic identity averaged 0.965 for amphi-atlantic comparisons) indicating that passive transport of juveniles or adults may contribute significantly to gene flow. Conversely, allozyme variation between karyotypes was concordant. High chromosome number populations possessed a suite of alleles at four allozyme loci (Esl-3, Lap-2, Mdh-1 and Pep-2) which were absent or rare in Group 2 samples resulting in high F_ST values for these loci (from 0.294 to 0.472) when karyotypic classes were combined. Consequently the mean genetic identity between these Robertsonian races is low, 0.856, and falls within the range more usually associated with congeneric comparisons than with con-specific comparisons. The mechanisms maintaining this genie difference are unclear. However the distribution of the karyotypes and physiological and morphological differences (in shell shape) between them strongly suggest that karyotypic variation in Nucella is adaptive.