Vanadium biochemistry: the unknown role of vanadium-containing cells in ascidians (sea squirts)

This article reviews several new developments in vanadium biochemistry, as elucidated from studies of ascidians. A hypothesis correlating ascidian blood cell function to anaerobiosis, via two prominent redox constituents, namely vanadium(III) and the tunichromes, a family of metal ion complexing/reducing hydroquinonoid peptides, is presented.     

Ultrastructure and biochemistry of the pineal organ in deep-sea lanternfishes (Myctophidae)

Summary Pineal structural and biochemical adaptations in lanternfishes included: 1) few photoreceptor outer segment discs; 2) conventional synapses between photoreceptors and pineal neurons; and 3) low levels (0–60 pg/pineal) of serotonin compared to those (>1.0 ng/pineal) in the goldfish pineal organ. These findings suggest reduced photosensory and/or neuroendocrine functions in these deep-sea fishes.     

The role of motile aeromonads in the fish disease, ulcerative disease syndrome (UDS)

Ulcerative Disease Syndrome (UDS) is an epizootic fish disease characterized by the presence of severe, open dermal ulcers on the head, midbody, and dorsal regions of the fish. Aeromonas hydrophila and A. sobria were recovered more often from UDS fish than other bacteria from the genera Vibrio, Alteromonas and Plesiomonas. Representative isolates of A. hydrophila, A. sobria, V. anguillarum, V. vulnificus, Alteromonas putrefaciens, and P. shigelloides taken from UDS and healthy fish were assayed for virulence-associated factors. The aeromonads produced a wide variety of hydrolytic enzymes and expressed cell surface characteristics linked to virulence whereas the other bacterial species rarely produced the same enzymes or cell surface characteristics. The role of aeromonads in UDS is believed to be opportunistic or secondary and these bacteria are thought to play an important role in this degenerative disease.     

Augmentation of natural antiganglioside IgM antibodies in lower motor neuron disease (LMND) and role of CD5+ B cells

IgM antibodies directed against neuronal gangliosides GM₁ , GM₂ , GD_1a , GD_1b and GT_1b occur in normal individuals and their level significantly decreases with age. Patients with lower motor neuron disease (LMND) produce high levels of these autoantibodies. AntiGM₁ IgM is selectively augmented. In these patients, the CD5+ (B1) and CD5− (B2) subsets of B cells are not distinct entities but range from those without detectable CD5 marker to those with high CD5+ expression. B1 B cells were sorted to homogeneity, but B2 B cell cannot be isolated to homogeneity because of the presence of B1 cells with low CD5 expression. In short term cultures both the subsets produced IgM antibodies, but the antibodies reacted better with desialylated GM₁ than with GM₁ . Cycloheximide (Cx) (0.35 mM) largely blocked IgM synthesis of the B1 B cells but inhibition of the B2 B cells was incomplete, possibly due to shedding of cytophilic antibodies as well as to the presence of B1 phenotype with loss of CD5 expression. CD5+ B cells may be involved in the production of antiglycolipid IgM. Received 9 June 1997; received after revision 21 July 1997; accepted 28 July 1997     

The occurrence of small,intensely fluorescent (SIF) cells in human sympathetic ganglia

Summary Small, intensely fluorescent (SIF) cells were found histochemically in lumbar sympathetic ganglia (L2) obtained from sympathectomy of 3 patients suffering from chronic occlusive diseases of leg arteries. 3 types of SIF cells were distinguished. These cells will probably contain dopamine.     

The explanatory role of abstraction processes in models: The case of aggregations

Though it is held that some models in science have explanatory value, there is no conclusive agreement on what provides them with this value. One common view is that models have explanatory value vis-à-vis some target systems because they are developed using an abstraction process (i.e., a process which involves omitting features). Though I think this is correct, I believe it is not the whole picture. In this paper, I argue that, in addition to the well-known process of abstraction understood as an omission of features or information, there is also a family of abstraction processes that involve aggregation of features or information and that these processes play an important role in endowing the models they are used to build with explanatory value. After offering a taxonomy of abstraction processes involving aggregation, I show by considering in detail several models drawn from different sciences that the abstraction processes involving aggregation that are used to build these models are responsible (at least partially) for their having explanatory value.     

Fine structure of modiffied phtoreceptor cells in the pineal of the gobyClevelandia ios (Pisces: Gobiidae)

Summary Photoreceptor cells with a system of long, thi cytoplasmic processes (50–80 nm thick), which amy represent a modification of the outer segment saccules, are described in the pineal of the goby,Clevelandia ios.The author wishes to thank Mr Larry Allen, who helped collect the specmens, and Mr Kyle Kikuchi, who was instrucmental in the preliminary studies.Partial support by Biomedical Research Support Grant (NIH) No. 447-12-000 from the Stritch School of Medicine is gratefully acknowledged.     

The fate of intramitochondrial paracrystalline inclusion bodies in germ line cells of water frogs (Amphibia,Anura)

Summary Numerous intramitochondrial pararystalline inclusion bodies (ICIB) were observed in the germinal plasm of a mid-blastula, and in primordial germ cells (PGCs) after their migration to the germinal ridges, inRana ridibunda, R. lessonae andR. esculenta. In oogonia the number of ICIB decreases rapidly. Single ICIB are observed in the germ cells up to the leptotene stage; they have never been observed in pachytene oocytes. In diplotene oocytes that have reached a diameter of about 100 m ICIB are visible again, and their number increases concomitantly with oocyte growth.     

The role of P-glycoprotein/cellular prion protein interaction in multidrug-resistant breast cancer cells treated with paclitaxel

We previously reported that treatment with P-glycoprotein (P-gp) substrates promotes in vitro invasion in multidrug-resistant (MDR) breast cancer cells. This effect is initiated by the P-gp pump function and mediated by interaction of P-gp with some unknown component(s). However, the underlying mechanism(s) remains poorly understood. Here we confirm a novel physical interaction between P-gp and cellular prion protein (PrP^c). Blocking P-gp activity or depletion of PrP^c inhibited paclitaxel (P-gp substrate)- induced invasion. Paclitaxel further facilitated the formation of P-gp/PrP^c clusters residing in caveolar domains and promoted the association of P-gp with caveolin-1. Both caveolin-1 and the integrity of caveolae were required for the drug-induced invasion. In addition, the P-gp/PrP^c complex also played an important role in anti-apoptotic activity of MCF7/Adr cells.These data provide new insights into the mode by which MDR breast cancers evade cytotoxic attacks from P-gp substrates and also suggest a role for P-gp/ PrP^c interaction in this process. Received 4 September 2008; received after revision 16 November 2008; accepted 18 November 2008     

Characterization and relative abundance of maxi-chloride channels in Epstein-Barr virus (EBV) producer: B95-8 cells

Several Epstein-Barr virus (EBV)-transformed cell lines were used to investigate the pathogenesis of lymphoproliferative diseases and nasopharyngeal carcinoma. The studies focus on the events occurring inside the membrane. On only one occasion, the cell membrane of EBV-transformed B lymphocytes from a cystic fibrosis patient was found to express defective Cl channels (CFTR; Cystic Fibrosis Transmembrane conductance Regulator), as in the airway epithelial cell. No other type of channel in EBV-transformed cells has so far been investigated. In this study, the cell membrane of the B95-8 cell was examined by the patch-clamp technique and compared to the non-EBV-infected BJAB cell. The high conductance (300 pS) maxi-chloride (Cl) channel activity was the most frequently observed event in inside-out configurations. Under similar experimental conditions, we have found a significantly higher probability of detecting maxi-Cl channel activity on the cell membrane of B95-8 cells (69%) than on BJAB cells (27%), or as previously reported on resting murine B lymphocytes (38%) or intact human T lymphocytes (37%). The relative abundance of the maxi-Cl channel on B95-8 cells may be linked to EBV infection and/or secretory ability.     

The phosphoinositide PI(3,5)P2 mediates activation of mammalian but not plant TPC proteins: functional expression of endolysosomal channels in yeast and plant cells

Two-pore channel proteins (TPC) encode intracellular ion channels in both animals and plants. In mammalian cells, the two isoforms (TPC1 and TPC2) localize to the endo-lysosomal compartment, whereas the plant TPC1 protein is targeted to the membrane surrounding the large lytic vacuole. Although it is well established that plant TPC1 channels activate in a voltage- and calcium-dependent manner in vitro, there is still debate on their activation under physiological conditions. Likewise, the mode of animal TPC activation is heavily disputed between two camps favoring as activator either nicotinic acid adenine dinucleotide phosphate (NAADP) or the phosphoinositide PI(3,5)P₂. Here, we investigated TPC current responses to either of these second messengers by whole-vacuole patch-clamp experiments on isolated vacuoles of Arabidopsis thaliana. After expression in mesophyll protoplasts from Arabidopsis tpc1 knock-out plants, we detected the Arabidopsis TPC1-EGFP and human TPC2-EGFP fusion proteins at the membrane of the large central vacuole. Bath (cytosolic) application of either NAADP or PI(3,5)P₂ did not affect the voltage- and calcium-dependent characteristics of AtTPC1-EGFP. By contrast, PI(3,5)P₂ elicited large sodium currents in hTPC2-EGFP-containing vacuoles, while NAADP had no such effect. Analogous results were obtained when PI(3,5)P₂ was applied to hTPC2 expressed in baker’s yeast giant vacuoles. Our results underscore the fundamental differences in the mode of current activation and ion selectivity between animal and plant TPC proteins and corroborate the PI(3,5)P₂-mediated activation and Na⁺ selectivity of mammalian TPC2.     

The presence of carotenoids in eggs deposits of theChironomus annularius meig (Diptera: Chironomidae)

Résumé A l'aide de la Chromatographie sur colonne et sur couche fine, les auteurs ont effectué la séparation des caroténoïdes des ufs deChironomus annularius Meig (Diptera: Chironomidae). Ces recherches ont attesté la présence du -carotene, de l'échinénone, de la cryptoxanthine et de la lutéine.     

Divergent effects of hyperosmolality on stress-response (heat shock) protein expression in cultured human tumor cells: an immunocytochemical study

Exposing cells to adverse conditions usually elicits expression of stress-response (heat shock) proteins (srp). Here we show that hyperosmolar growth conditions do not uniformly affect srp expression in MCF-7 and HeLa S3 cells, derived from carcinoma of the breast and cervix, respectively. Thus, whereas srp 27 expression was increased in MCF-7, but not in HeLa S3, the opposite was the case with srp 72. On the other hand, hyperosmolality did not induce B-crystallin or ubiquitin in either cell line. These findings show that srp expression by the human tumor cells studied is non-coordinate, suggesting that each srp is independently modulated.