Age-dependent strategies related to lionfish activities in the Mexican Caribbean

Lionfish are successful invasive predators in the Caribbean region and inhabit a large range of habitats. Our study in the Caribbean has focused on the relationships between the biological characteristics of lionfish particularly their size, their activities and use of those different habitats. In this study, we observed a high number of lionfish individuals, focusing on the behavioural activities and biological traits in relation to different habitats and environmental characteristics. We monitored 793 individuals, recording their activities, biological traits, and habitat characteristics. Our results report that lionfish are not solitary, but frequently form groups for many activities. We provide evidence of differences between lionfish habitat use according to activity, and the size of individual fish. Considering the size is correlated with age, coral reefs appear to be the preferred habitat of older individuals, whereas the youngest lionfish use a diversity of habitats, ranging from mangroves to coral reefs. In addition, this study suggests that predation of lionfish is age-dependent strategy, and depends on time and the tone of the environment. Lionfish do not only use the head-down posture to catch prey but also horizontal and head-up postures. The youngest lionfish hunt mainly in dark areas and during the night while the older fish were observed hunting mostly during the day and in clear areas. These new aspects of lionfish ecology and behaviour are discussed in light of their invasive success.     

Biochemical characterization of the interaction between HspA1A and phospholipids

Seventy-kilodalton heat shock proteins (Hsp70s) are molecular chaperones essential for maintaining cellular homeostasis. Apart from their indispensable roles in protein homeostasis, specific Hsp70s localize at the plasma membrane and bind to specific lipids. The interaction of Hsp70s with lipids has direct physiological outcomes including lysosomal rescue, microautophagy, and promotion of cell apoptosis. Despite these essential functions, the Hsp70-lipid interactions remain largely uncharacterized. In this study, we characterized the interaction of HspA1A, an inducible Hsp70, with five phospholipids. We first used high concentrations of potassium and established that HspA1A embeds in membranes when bound to all anionic lipids tested. Furthermore, we found that protein insertion is enhanced by increasing the saturation level of the lipids. Next, we determined that the nucleotide-binding domain (NBD) of the protein binds to lipids quantitatively more than the substrate-binding domain (SBD). However, for all lipids tested, the full-length protein is necessary for embedding. We also used calcium and reaction buffers equilibrated at different pH values and determined that electrostatic interactions alone may not fully explain the association of HspA1A with lipids. We then determined that lipid binding is inhibited by nucleotide-binding, but it is unaffected by protein-substrate binding. These results suggest that the HspA1A lipid-association is specific, depends on the physicochemical properties of the lipid, and is mediated by multiple molecular forces. These mechanistic details of the Hsp70-lipid interactions establish a framework of possible physiological functions as they relate to chaperone regulation and localization.

Electronic supplementary material

The online version of this article (doi:10.1007/s12192-015-0636-6) contains supplementary material, which is available to authorized users.     

Recognition sequences of repressor and polymerase in the operators of bacteriophage lambda

Nucleotide sequences in two wild-type and six mutant operators in the DNA of phage λ are compared. Strikingly similar 17 base pair units are found which we identify as the repressor binding sites. Each operator contains multiple repressor binding sites separated by A-T rich spacers. Elements of 2 fold rotational symmetry are present in each of the sites. Superimposed on each operator is an E. coli RNA polymerase recognition site (promoter). Similarities in the sequences of the two λ promoters, a lac promoter, and an E. coli RNA polymerase recognition site in SV40 DNA are noted.     

Regulatory elements involved in Drosophila Adh gene expression are conserved in divergent species and separate elements mediate expression in different tissues.

Alcohol dehydrogenase (ADH) is expressed in a complex temporal and spatial pattern from tandem promoters (proximal and distal) in Drosophila melanogaster, and from two closely linked genes (Adh-1 and Adh-2) in D. mulleri. The expression patterns of Adh-1 and the proximal promoter, and Adh-2 and the distal promoter are similar, but not identical. We show that the mulleri Adh genes are appropriately expressed when introduced into the melanogaster genome, indicating that the cis- and trans-acting elements which regulate the corresponding promoters are functionally equivalent in the two species. By analyzing the expression of in vitro generated mutants of the mulleri Adh locus, we define at least three regulatory regions of the mulleri Adh genes and show that different control elements mediate the expression of Adh in different tissues.     

Activation of the human beta-interferon gene requires an interferon-inducible factor.

beta-Interferon (beta-IFN) gene expression can be induced by poly(I)-poly(C) or virus, but there is considerable variation in the extent of induction between different cell lines. We characterized two poorly inducible human cell lines, HeLa and 143 thymidine kinase negative (143 tk-), to define cellular factors involved in the activation of the beta-IFN gene. We show that the deficiency in beta-IFN induction in these cells can be complemented by fusion to highly inducible mouse cells. We conclude that the human cells are deficient in a trans-acting factor required for B-IFN gene activation. The level of induction of the beta-IFN gene in HeLa and 143 tk- cells can also be increased by priming with IFN before induction. If IFN priming is carried out in the presence of cycloheximide, a approximately 200-fold increase in induction is observed. We conclude that activation of the beta-IFN gene requires an IFN-inducible factor that is only expressed at low levels in unprimed HeLa and 143 tk- cells.     

Identification of two distinct regulatory regions adjacent to the human beta-interferon gene

To study the regulation of the human beta-interferon (beta-IFN) gene by poly(I)-poly(C), we analyzed the expression of deletion mutants of the cloned gene introduced into mouse cells on a new bovine papilloma virus (BPV) vector. In stable cell lines transformed by a BPV-IFN plasmid containing the beta-IFN structural gene with 210 bp of DNA to the 5' side of its mRNA cap site (denoted -210), human beta-IFN mRNA is induced approximately 400-fold by poly(I)-poly(C), and reproducible levels of expression are observed for independent cell lines. Our studies indicate that there are two distinct regulatory regions adjacent to the gene, located between -77 and -19, and between -210 and -107. The -77 to -19 region is required for constitutive and induced IFN gene expression, and both are drastically reduced by deletion to -73. When sequences between -210 and -107 are deleted, the constitutive level of IFN gene expression is increased 5- to 10-fold, while induced expression is essentially unaffected. Deletion of the -210 to -107 region also alters the kinetics of induction of the gene.     

ERYTHROPOIESIS DURING AMPHIBIAN METAMORPHOSIS : III. Immunochemical Detection of Tadpole and Frog Hemoglobins (Rana catesbeiana) in Single Erythrocytes

Rabbit antibodies specific for the major tadpole and frog hemoglobin components of R. catesbeiana were used for the detection of the two hemoglobins inside single cells. The antisera, after fractionation by ammonium sulfate precipitation and diethylaminoethyl (DEAE)-cellulose chromatography, were conjugated with fluorescein isothiocyanate for the antifrog hemoglobin serum and tetramethylrhodamine isothiocyanate for the antitadpole hemoglobin serum. The conjugated fractions, refractionated by stepwise elution from a DEAE-cellulose column, were used for the fluorescent staining of blood smears, liver tissue imprints, and smears of liver cell suspensions. Both simultaneous and sequential staining with the two fluorescent preparations indicated that larval and adult hemoglobins were not present within the same erythrocyte during metamorphosis. In other experiments, erythroid cells from animals in metamorphosis were spread on agar containing specific antiserum. Precipitates were formed around the cells which contain the particular hemoglobin. The percentages of cells containing either tadpole or frog hemoglobin were estimated within the experimental error of the method. The data showed that the two hemoglobins are in different cells. It is concluded that the hemoglobin change observed during the metamorphosis of R. catesbeiana is due to the appearance of a new population of erythroid cells containing exclusively frog hemoglobin.