Life-stage-specific differences in exploitation of food mixtures: diet mixing enhances copepod egg production but not juvenile development

Development, egg production and hatching success of the calanoidcopepods Temora longicornis and Pseudocalanus elongatus weremeasured in food mixtures to test their ability to obtain acomplete nutrition by combining different nutritionally poorfood species. In all the food mixtures used, the copepods failedto moult past the first copepodite stage, and the mortalitywas high. In sharp contrast, mixing two nutritionally poor foodspecies often resulted in egg production which was not significantlydifferent from nutritionally high quality food, although hatchingsuccess in many mixtures was low. Whereas egg production wassignificantly correlated with particulate organic nitrogen inthe diet, and independent of the highly unsaturated fatty acids(HUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid(DHA), hatching increased with increasing DHA and EPA concentration.Growth and juvenile mortality were, however, independent ofeither nitrogen or HUFAs in the diet. Our results show thatadult copepods are effective in combining their nutrition fromseveral food sources, whereas juveniles are not. We suggestthat there are species- and life-stage-specific differencesin nutritional requirements and/or in the ability to digestand/or assimilate essential nutrients from food mixtures, whichmay significantly contribute to the success of copepod populationsin nature.     

CD10 expression in non-small cell lung cancer.

CD10 is a cell surface endopeptidase that inactivates various potentially growth stimulatory peptides. In lung cancer cell lines this downregulation has been associated with increased proliferation. Downregulation of CD10 in lung cancer tissue is described, suggesting a potential role in carcinogenesis and a possible use of CD10 as a prognostic marker. We aimed to determine the rate of CD10 expression in our non-small cell lung cancer (NSCLC) collection and to clarify its correlation with clinicopathological parameters and patient survival. 114 NSCLC were analysed immunohistochemically using a monoclonal CD10 antibody (clone NCL-CD10-270) on an NSCLC tissue micro array. The staining was semiquantitatively scored. CD10 expression was observed in 19% of cases, without any significant association with tumour type, -size, -grading, nodal status, clinical stage, and patient survival time. We conclude that a diagnostic use of CD10 immunostaining in NSCLC is unlikely.     

In Vitro and In Vivo Invasiveness of Different Pulsed-Field Gel Electrophoresis Types of Listeria monocytogenes

The virulence of different pulsed-field gel electrophoresis (PFGE) types of Listeria monocytogenes was examined by monitoring their ability to invade Caco-2 cells. Strains belonging to seven different PFGE types originating from both foods and humans were included. No significant differences in invasiveness were detected between strains isolated from humans and those isolated from food. Strains belonging to PFGE type 1 expressed a significantly lower ability to invade cells compared to strains belonging to other PFGE types. Although strains of PFGE type 2 also seemed to invade at a low level, this was not significant in the present study. PFGE types 1 and 2 as well as type 14 are more frequently found in food than the four other PFGE types examined and moreover have a relatively low prevalence in humans compared to their prevalence in food. Thus, the hypothesis that some PFGE types are less virulent than others is supported by this study showing that certain PFGE types of L. monocytogenes commonly found in food are less invasive than others to Caco-2 cells. In contrast to the differences in invasion, identical intracellular growth rates between the different PFGE types were observed. In vivo studies of the actual ability of the strains to invade the liver and spleen of cimetidine-treated rats following an oral dose of 10⁹ L. monocytogenes cells were performed for isolates of PFGE types 1, 2, 5, and 15. After 2 days, equal amounts of bacteria were observed in the liver and spleen of the rats for any of the PFGE types tested.     

GENETIC VARIABILITY AND MOLECULAR PHYLOGENY OF DINOPHYSIS SPECIES (DINOPHYCEAE) FROM NORWEGIAN WATERS INFERRED FROM SINGLE CELL ANALYSES OF rDNA1

The objectives of this study were to determine rDNA sequences of the most common Dinophysis species in Scandinavian waters and to resolve their phylogenetic relationships within the genus and to other dinoflagellates. A third aim was to examine the intraspecific variation in D. acuminata and D. norvegica, because these two species are highly variable in both morphology and toxicity. We obtained nucleotide sequences of coding (small subunit [SSU], partial large subunit [LSU], 5.8S) and noncoding (internal transcribed spacer [ITS]1, ITS2) parts of the rRNA operon by PCR amplification of one or two Dinophysis cells isolated from natural water samples. The three photosynthetic species D. acuminata, D. acuta, and D. norvegica differed in only 5 to 8 of 1802 base pairs (bp) within the SSU rRNA gene. The nonphotosynthetic D. rotundata (synonym Phalacroma rotundatum[Claparède et Lachmann] Kofoid et Michener), however, differed in approximately 55 bp compared with the three photosynthetic species. In the D1 and D2 domains of LSU rDNA, the phototrophic species differed among themselves by 3 to 12 of 733 bp, whereas they differed from D. rotundata by more than 100 bp. This supports the distinction between Dinophysis and Phalacroma. In the phylogenetic analyses based on SSU rDNA, all Dinophysis species were grouped into a common clade in which D. rotundata diverged first. The results indicate an early divergence of Dinophysis within the Dinophyta. The LSU phylogenetic analyses, including 4 new and 11 Dinophysis sequences from EMBL, identified two major clades within the phototrophic species. Little or no intraspecific genetic variation was found in the ITS1–ITS2 region of single cells of D. norvegica and D. acuminata from Norway, but the delineation between these two species was not always clear.     

Nucleic acid capture assay,a new method for direct quantitation of nucleic acids

Technologies allowing direct detection of specific RNA/DNA sequences occasionally serve as an alternative to amplification methods for gene expression studies. In these direct methods the hybridization of probes takes place in complex mixtures, thus specificity and sensitivity still limit the use of current technologies. To address these challenges, we developed a new technique called the nucleic acid capture assay, involving a direct multi-capture system. This approach combines a 3′-ethylene glycol scaffolding with the incorporation of 2′-methoxy deoxyribonucleotides in the capture sequences. In our design, all nucleotides other than those complementary to the target mRNA have been replaced by an inert linker, resulting in significant reductions in non-specific binding. We also provide a versatile method to detect the presence of captured targets by using specific labeled probes with alkaline phosphatase-conjugated anti-label antibodies. This direct, flexible and reliable technique for gene expression analysis is well suited for high-throughput screening and has potential for DNA microarray applications.     

Cryptic population structure in a large,mobile mammalian predator: the Scandinavian lynx

The Eurasian lynx (Lynx lynx) is an example of a species that has gone through a severe bottleneck, leading to near extinction in Scandinavia around 1930-- a pattern shared with several other large carnivorous mammals. Here we extend previous genetic analyses of northern European lynx, confirming that lynx from the Scandinavian Peninsula represent a distinct clade differing clearly from European conspecifics. Furthermore, and despite a recent bottleneck and subsequent range expansion, we detect marked genetic differentiation within Scandinavia. This differentiation is largely manifested as a north-south gradient, with a linear increase in the quantity FST/(1 - FST). Aided by computer simulations we find that this pattern is unlikely to have arisen by random genetic drift in the short time since lynx started to expand in the 1950s, suggesting that the spatial structure may predate the bottleneck. Individual-based analyses indicate that, instead of a continuous gradient, Scandinavian lynx may be structured into three more or less distinct groups, possibly corresponding to northern, central and southern subpopulations. The presence of such structuring was unknown previously and was unexpected from general considerations on the mobility of the species, historical data and the absence of geographical barriers. Our study demonstrates how molecular markers may be used to detect cryptic population structure, invisible using traditional methods.     

Case study of the distribution of mucosa-associated Bifidobacterium species, Lactobacillus species, and other lactic acid bacteria in the human colon

The distribution of mucosa-associated bacteria, bifidobacteria and lactobacilli and closely related lactic acid bacteria, in biopsy samples from the ascending, transverse, and descending parts of the colon from four individuals was investigated by denaturing gradient gel electrophoresis (DGGE). Bifidobacterial genus-specific, Lactobacillus group-specific, and universal bacterial primers were used in a nested PCR approach to amplify a fragment of the 16S rRNA gene. DGGE profiles of the bifidobacterial community were relatively simple, with one or two amplicons detected at most sampling sites in the colon. DGGE profiles obtained with Lactobacillus group-specific primers were complex and varied with host and sampling site in the colon. The overall bacterial community varied with host but not sampling site.     

Degradation of African locust bean oil by Bacillus subtilis and Bacillus pumilus isolated from soumbala,a fermented African locust bean condiment

AIMS: To investigate predominant isolates of Bacillus subtilis and B. pumilus in soumbala, a fermented African locust bean condiment, for their ability to degrade African locust bean oil (ALBO). METHODS AND RESULTS: Agar diffusion test in tributyrin and ALBO agar was used for screening of the isolates for esterase and lipase activity, respectively. The quantity and the profile of free fatty acids (FFA) during 72 h of degradation of ALBO by the Bacillus isolates were studied by titration and gas chromatography. The degradation of tributyrin and ALBO was variable among the isolates. Two strains of B. subtilis and two strains of B. pumilus showed significantly higher esterase and lipolytic activities than the others. The degradation ALBO was most pronounced in enriched nutrient agar except for one isolate of B. pumilus degrading ALBO to the same extent regardless of the enrichment. The quantity of FFA released from ALBO by the most lipolytic strains of Bacillus increased mainly between 0 and 24 h and differed among the isolates. The profile of FFA was similar for the Bacillus isolates with oleic acid (C18:2) occurring as the major FFA in all the samples except in samples incubated with B. subtilis B9 where stearic acid (C18) was dominant. CONCLUSION: Bacillus isolates from soumbala showed high strain dependent lipolytic activity against ALBO. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to the selection of Bacillus strains to be used as starter cultures for controlled production of soumbala.     

Stem cells from the adult human brain develop into functional neurons in culture

Recent research communications indicate that the adult human brain contains undifferentiated, multipotent precursors or neural stem cells. It is not known, however, whether these cells can develop into fully functional neurons. We cultured cells from the adult human ventricular wall as neurospheres and passed them at the individual cell level to secondary neurospheres. Following dissociation and plating, the cells developed the antigen profile of the three main cell types in the brain (GFAP, astrocytes; O2, oligodendrocytes; and beta-III-tubulin/NeuN, neurons). More importantly, the cells developed the electrophysiological profiles of neurons and glia. Over a period of 3 weeks, neuron-like cells went through the same phases as neurons do during development in vivo, including up-regulation of inward Na+ -currents, drop in input resistance, shortening of the action potential, and hyperpolarization of the cell membrane. The cells developed overshooting action potentials with a mature configuration. Recordings in voltage-clamp mode displayed both the fast inactivating TTX-sensitive sodium current (INa) underlying the rising phase of the action potential and the two potassium currents terminating the action potential in mature neurons (IA and IK, sensitive to 4-AP and TEA, respectively). We have thus demonstrated that the human ventricular wall contains multipotent cells that can differentiate into functionally mature neurons.