Characterization of apoptosis induced by fucoxanthin in human promyelocytic leukemia cells

Apoptosis induced by fucoxanthin in HL-60 cells was associated with a loss of mitochondrial membrane potential at an early stage, but not with an increase in reactive oxygen species. Fucoxanthin treatment caused cleavages of procaspase-3 and poly (ADP-ribose) polymerase without any effect on the protein level of Bcl-2, Bcl-X(L), or Bax. Apoptosis induction by fucoxanthin may be mediated via mitochondrial membrane permeabilization and caspase-3 activation.     

Sex pheromone biosynthesis in Ostrinia zaguliaevi, a congener of the European corn borer moth O. nubilalis

In order to clarify the biochemical basis to the divergence of sex pheromones in the genus Ostrinia (Lepidoptera: Crambidae), the pheromone biosynthetic pathway in O. zaguliaevi, a close relative of the European corn borer O. nubilalis, was investigated. Deuterium-labeled hexadecanoic or tetradecanoic acids were topically applied to the surface of the pheromone gland, and the incorporation of the label into pheromone components and their putative precursors was determined. It was suggested that the two components shared by O. zaguliaevi and O. nubilalis, (E)-11- and (Z)-11-tetradecenyl acetates, are biosynthesized from hexadecanoic acid through one round of chain shortening, Delta11 desaturation, reduction, and acetylation. An additional component specifically found in O. zaguliaevi, (Z)-9-tetradecenyl acetate, is likely to be produced by delta11 desaturation of hexadecanoic acid, one round of chain shortening, reduction, and acetylation. Non-production of (Z)-9-tetradecenyl acetate in O. nubilalis was suggested to be due to the blockage of chain shortening from (Z)-11-hexadecenoate to (Z)-9-tetradecenoate.     

Schistosome membrane proteins as vaccines

Schistosomes are parasitic blood flukes that infect approximately 200 million people and are arguably the most important human helminth in terms of mortality. The outermost surface of intra-mammalian stages of the parasite, the tegument, is the key to the parasite's success, but it is also generally viewed as the most susceptible target for vaccines and drugs. Over the past 2 years the proteome of the Schistosoma mansoni tegument has been investigated and these studies revealed surprisingly few proteins that are predicted to be accessible to the host immune response, namely proteins with at least one membrane-spanning domain. However, of this handful of proteins, some are showing great promise as recombinant vaccines against schistosomiasis at a pre-clinical level. In particular, the tetraspanin family of integral membrane proteins appears to be abundantly represented in the tegument, and convergent data using the mouse vaccine model and correlates of protective immunity in naturally exposed people suggests that this family of membrane proteins offer great promise for schistosomiasis vaccines. With the recent advances in schistosome genomics and proteomics, a new suite of potential vaccine antigens are presented and these warrant detailed investigation and appropriate funding over the next few years.     

The p16INK4a tumor suppressor controls p21WAF1 induction in response to ultraviolet light

p16^INK4a and p21^WAF1, two major cyclin-dependent kinase inhibitors, are the products of two tumor suppressor genes that play important roles in various cellular metabolic pathways. p21^WAF1 is up-regulated in response to different DNA damaging agents. While the activation of p21^WAF1 is p53-dependent following γ-rays, the effect of ultraviolet (UV) light on p21^WAF1 protein level is still unclear. In the present report, we show that the level of the p21^WAF1 protein augments in response to low UVC fluences in different mammalian cells. This up-regulation is mediated through the stabilization of p21^WAF1 mRNA in a p16^INK4a-dependent manner in both human and mouse cells. Furthermore, using p16-siRNA treated human skin fibroblast; we have shown that p16 controls the UV-dependent cytoplasmic accumulation of the mRNA binding HuR protein. In addition, HuR immunoprecipitations showed that UV-dependent binding of HuR to p21 mRNA is p16-related. This suggests that p16 induces p21 by enabling the relocalization of HuR from the nucleus to the cytoplasm. Accordingly, we have also shown that p16 is necessary for efficient UV-dependent p53 up-regulation, which also requires HuR. These results indicate that, in addition to its role in cell proliferation, p16^INK4a is also an important regulator of the cellular response to UV damage.     

Hsp60 is targeted to a cryptic mitochondrion-derived organelle ("crypton") in the microaerophilic protozoan parasite Entamoeba histolytica

Entamoeba histolytica is a microaerophilic protozoan parasite in which neither mitochondria nor mitochondrion-derived organelles have been previously observed. Recently, a segment of an E. histolytica gene was identified that encoded a protein similar to the mitochondrial 60-kDa heat shock protein (Hsp60 or chaperonin 60), which refolds nuclear-encoded proteins after passage through organellar membranes. The possible function and localization of the amebic Hsp60 were explored here. Like Hsp60 of mitochondria, amebic Hsp60 RNA and protein were both strongly induced by incubating parasites at 42 degreesC. 5' and 3' rapid amplifications of cDNA ends were used to obtain the entire E. histolytica hsp60 coding region, which predicted a 536-amino-acid Hsp60. The E. histolytica hsp60 gene protected from heat shock Escherichia coli groEL mutants, demonstrating the chaperonin function of the amebic Hsp60. The E. histolytica Hsp60, which lacked characteristic carboxy-terminal Gly-Met repeats, had a 21-amino-acid amino-terminal, organelle-targeting presequence that was cleaved in vivo. This presequence was necessary to target Hsp60 to one (and occasionally two or three) short, cylindrical organelle(s). In contrast, amebic alcohol dehydrogenase 1 and ferredoxin, which are bacteria-like enzymes, were diffusely distributed throughout the cytosol. We suggest that the Hsp60-associated, mitochondrion-derived organelle identified here be named "crypton," as its structure was previously hidden and its function is still cryptic.     

Stage Specific Glycosylation Pattern for Lactoseries Carbohydrates in the Developing Chick Retina

Based on the idea of differentiation-related changes in the glycosylation pattern of neurons, the expression of two cell surface oligosaccharide epitopes, N-acetyl-lactosamine (NALA), and its sulpho-glucuronyl derivative (HNK-1), was studied, by immunohistochemistry and Western blot experiments, in the developing chick retina beginning on day 2 of incubation (E2) until day 18 post-hatching. NALA was detectable on neuroepithelial cells as soon as the primary optic vesicles formed, and this pattern continued until E3. During subsequent retinal development NALA expression became progressively restricted in concert with the appearance of postmitotic neurons as revealed by neurite outgrowth, and with the formation of synaptic contacts until it disappeared at the end of the incubation period. The pattern of NALA expression was the inverse of HNK-1 which was detected for the first time at E3 on postmitotic ganglion cells accumulating at the vitreal surface. The number of HNK-1+ cells steadily increased until around E10, when the entire neural epithelium was labelled. Synchronously to synaptogenesis, most neurons lost their HNK-1 immunoreactivity. At the time of hatching the adult-like pattern was found, characterised by subpopulations of labelled horizontal, bipolar, amacrine, and ganglion cells. Immunoblot experiments demonstrated transient NALA glycosylation of protein bands, partially identical in their apparent molecular weight to those proteins with HNK-1 glycosylation. The observed temporospatial changes in the glycosylation patterns of distinct proteins during retinal development suggest NALA as a suitable marker for neuronal proliferation, and HNK-1 for differentiation and establishment of final synaptic configuration.     

Alcohol and aldehyde dehydrogenase genotypes and alcoholism in Chinese men.

The liver enzymes alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which are responsible for the oxidative metabolism of ethanol, are polymorphic in humans. An allele encoding an inactive form of the mitochondrial ALDH2 is known to reduce the likelihood of alcoholism in Japanese. We hypothesized that the polymorphisms of both ALDH and ADH modify the predisposition to development of alcoholism. Therefore, we determined the genotypes of the ADH2, ADH3, and ALDH2 loci of alcoholic and nonalcoholic Chinese men living in Taiwan, using leukocyte DNA amplified by the PCR and allele-specific oligonucleotides. The alcoholics had significantly lower frequencies of the ADH2*2, ADH3*1, and ALDH2*2 alleles than did the nonalcoholics, suggesting that genetic variation in both ADH and ALDH, by modulating the rate of metabolism of ethanol and acetaldehyde, influences drinking behavior and the risk of developing alcoholism.     

Unique features of the rice blast resistance <Emphasis Type="Italic">Pish</Emphasis> locus revealed by large scale retrotransposon-tagging

Background  

R gene-mediated resistance is one of the most effective mechanisms of immunity against pathogens in plants. To date some components that regulate the primary steps of plant immunity have been isolated, however, the molecular dissection of defense signaling downstream of the R proteins remains to be completed. In addition, R genes are known to be highly variable, however, the molecular mechanisms responsible for this variability remain obscure.     

Sequences and Evolution of Human and Squirrel Monkey Blue Opsin Genes

The sequences of the entire blue opsin gene in the squirrel monkey (Saimiri boliviensis) and the five introns of the human blue opsin gene were obtained. Intron 3 of these genes contains an Alu sequence and intron 4 contains a partial mer13 sequence. A comparison of the squirrel monkey opsin sequence with published mammalian opsin sequences shows that features believed to be functionally critical are all conserved. However, the blue opsin has evolved twice as fast as rhodopsin and is only as conservative as the β globin, which has evolved at the average rate of mammalian proteins. Interestingly, the interhelical loops are, on average, actually more conservative than the transmembrane α helical regions. The introns of the blue opsin gene have evolved at the average rate of introns in primate genes. Received: 5 August 1996 / Accepted: 2 October 1996     

Alterations in photosynthetic pigments and amino acid composition of D1 protein change energy distribution in photosystem II

The marine cyanobacterium Prochlorococcus marinus accumulates divinyl chlorophylls instead of monovinyl chlorophylls to harvest light energy. As well as this difference in its chromophore composition, some amino acid residues in its photosystem II D1 protein were different from the conserved amino acid residues in other photosynthetic organisms. We examined PSII complexes isolated from mutants of Synechocystis sp. PCC 6803, in which chromophore and D1 protein were altered (Hisashi Ito and Ayumi Tanaka, 2011) to clarify the effects of chromophores/D1 protein composition on the excitation energy distribution. We prepared the mutants accumulating divinyl chlorophyll (DV mutant). The amino acid residues of V205 and G282 in the D1 protein were substituted with M205 and C282 in the DV mutant to mimic Prochlorococcus D1 protein (DV-V205M/G282C mutant). Isolated PSII complexes were analyzed by time-resolved fluorescence spectroscopy. Energy transfer in CP47 was interrupted in PSII containing divinyl chlorophylls. The V205M/G282C mutation did not recover the energy transfer pathway in CP47, instead, the mutation allowed the excitation energy transfer from CP43 to CP47, which neighbors in the PSII dimer. Mutual orientation of the subcomplexes of PSII might be affected by the substitution. The changes of the energy transfer pathways would reduce energy transfer from antennae to the PSII reaction center, and allow Prochlorococcus to acquire light tolerance.