Iodine concentration of milk in a dose–response study with dairy cows and implications for consumer iodine intake

Most feed is poor in iodine and iodine supplementation of cow's diets must guarantee milk iodine concentrations for humans that contribute to prevention of the deficiency and minimize the risk of exceeding an upper limit of iodine intake. Five Holstein cows were fed four iodine doses (via Ca(ΙO₃)₂·6H₂O). In four sequential 14-d periods, doses of 0.2 (basal diet), 1.3, 5.1, and 10.1 mg iodine kg^?1 diet dry matter (DM) were administered. Samples of milk were collected during each period; blood was also sampled from each cow for each iodine dosage. In an 18-d depletion period, a non-supplemented diet was provided. Iodine was determined by inductively coupled plasma-mass spectrometry. The iodine content of milk and serum reflected the iodine dosages in feed significantly. The levels for the four doses tested in milk were 101±32, 343±109, 1215±222, and 2762±852 μg iodine kg^?1. The total amount of iodine in milk per day was 30–40% of ingested supplemental iodine. Omitting additional iodine resulted in a short-term reduction of serum and milk iodine following an exponential decay function. The iodine supplementation of 0.5–1.5 mg kg^?1 diet DM represents the requirement of the cow, resulting in 100–300 μg iodine L^?1 milk, which optimally contributes to human supply. The maximum dietary levels of former and present EU legislations (10 and 5 mg iodine kg^?1 cow feed) increase the risk of iodine excess in humans.     

Molecular regulation of cardiac ryanodine receptor ion channel

The release of Ca(2+) ions from intracellular stores is a key step in a wide variety of cellular functions. In striated muscle, the release of Ca(2+) from the sarcoplasmic reticulum (SR) leads to muscle contraction. Ca(2+) release occurs through large, high-conductance Ca(2+) release channels, also known as ryanodine receptors (RyRs) because they bind the plant alkaloid ryanodine with high affinity and specificity. The RyRs are isolated as 30S protein complexes comprised of four 560 kDa RyR2 subunits and four 12 kDa FK506 binding protein (FKBP12) subunits. Multiple endogenous effector molecules and posttranslational modifications regulate the RyRs. This review focuses on current research toward understanding the control of the isolated cardiac Ca(2+) release channel/ryanodine receptor (RyR2) by Ca(2+), calmodulin, thiol oxidation/reduction and nitrosylation, and protein phosphorylation.     

Studies on the evolutionary relationships between hemoglobins inChironomus pallidivittatus andC. Tentans

Summary The monomeric hemoglobins ofChironomus tentans andC. pallidivittatus have been isolated and separated into their respective components by gel chromatography on Sephadex G-75 and ion-exchange chromatography on DEAE-Sephacel. The amino acid compositions of the purified components are given. The sequence of the 30 N-terminal amino acid residues of one of the monomeric components (Hb I fromC. pallidivittatus) was determined and found to be identical in almost all of its parts with the monomeric hemoglobins ofC. thummi (CTT III and CTT IV).Antibodies against the monomeric hemoglobins Hb I and Hb IIc and the dimeric fraction were highly specific and no cross reaction between dimeric and monomeric hemoglobins could be demonstrated. The antibodies against the monomers crossreact with the monomeric hemoglobins CTT III and CTT IV ofC. thummi. Taken together with genetic data, the immunological results indicate that divergence of monomeric from dimeric forms was an early event in the evolution of the various hemoglobins inChironomus.     

Alarmlaute europ?ischer und nordafrikanischer Tannenmeisen(Parus ater ater, P. ater atlas, P. ater ledouci) und der Schwarzschopfmeise(P. melanolophus)

Zusammenfassung Die Alarmlaute europäischer und nordafrikanischer Tannenmeisen gegen Nesträuber sind sehr verschieden (Abb. a, c). Europäische Tannenmeisen verwenden den nordafrikanischen Typ nur bei größter Erregung (eine Beobachtung an wildlebenden). Europäische Tannenmeisen und Schwarzschopfmeisen, die zusammen mit marokkanischen Tannenmeisen in einer Voliere gehalten wurden, brachten in Alarmsituationen zuerst die ihnen gemäßen Rufe und dann die der nordafrikanischen (Abb. d). Wahrscheinlich ist der afrikanische Alarmruftyp der ursprüngliche. Der stammesgeschichtlich junge Alarmruftyp der UntergattungPeriparus ging den nordafrikanischen Populationen verloren.

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Alarm calls of European and North African Coal Tits(Parus ater ater, P. ater atlas, P. ater ledouci) and Vigor's Black Crested Tit(P. melanolophus)

Summary The alarm call against nestpredators of European and North African Coal Tits are quite different (fig. a, c). European Coal Tits call like African Coal Tits only in situations of drastic excitement (one observation in the field). European Coal Tits and Vigor's Black Crested Tits, kept together with Coal Tits from Morocco in an aviary, used in alarm situations first their usual calls and then the calls of the North African subspecies (Abb. d). Apparently the African form of the alarm call is the older. The North African populations have lost the evolutionarity young form of the alarm call of the subgenusPeriparus.

     

Ultrastructure,tactic behaviour and potential for sulfate reduction of a novel multicellular magnetotactic prokaryote from North Sea sediments

Multicellular magnetotactic prokaryotes (MMPs) represent highly organized, spherical and motile aggregates of 10–40 bacterial cells containing magnetosomes. Although consisting of different cells, each with its own magnetosomes and flagellation, MMPs orient themselves within a magnetic field and exhibit magnetotaxis. So far, MMPs have only been found in several North and South American coastal lagoons and salt marshes. In the present study, a novel type of MMP was discovered in coastal tidal sand flats of the North Sea. High‐resolution scanning electron microscopy revealed the presence of bullet‐shaped magnetosomes which were aligned in several parallel chains. Within each aggregate, the magnetosome chains of individual cells were oriented in the same direction. Energy dispersive X‐ray (EDX) analysis showed that the magnetosomes are composed of iron sulfide. This particular morphology and arrangement of magnetosomes has previously not been reported for other MMPs. 16S rRNA gene sequence analysis revealed a single phylotype which represented a novel phylogenetic lineage with ≥ 4% sequence divergence to all previously described MMP sequences and was related to the dissimilatory sulfate‐reducing Desulfosarcina variabilis within the family Desulfobacteraceae of the subphylum Deltaproteobacteria. Fluorescence in situ hybridization with a specific oligonucleotide probe revealed that all MMPs in the tidal flat sediments studied belonged to the novel phylotype. Within each MMP, all bacterial cells showed a hybridization signal, indicating that the aggregates are composed of cells of the same phylotype. Genes for dissimilatory sulfite reductase (dsrAB) and dissimilatory adenosine‐5′‐phosphate reductase (aprA) could be detected in purified MMP samples, suggesting that MMPs are capable of sulfate reduction. Chemotaxis assays with 41 different test compounds yielded strong responses towards acetate and propionate, whereas other organic acids, alcohols, sugars, sugar alcohols or sulfide did not elicit any response. By means of its coordinated magnetotaxis and chemotaxis, the novel type of MMP is well adapted to the steep chemical gradients which are characteristic for intertidal marine sediments.     

Differential distribution of competence for panplacodal and neural crest induction to non-neural and neural ectoderm

It is still controversial whether cranial placodes and neural crest cells arise from a common precursor at the neural plate border or whether placodes arise from non-neural ectoderm and neural crest from neural ectoderm. Using tissue grafting in embryos of Xenopus laevis, we show here that the competence for induction of neural plate, neural plate border and neural crest markers is confined to neural ectoderm, whereas competence for induction of panplacodal markers is confined to non-neural ectoderm. This differential distribution of competence is established during gastrulation paralleling the dorsal restriction of neural competence. We further show that Dlx3 and GATA2 are required cell-autonomously for panplacodal and epidermal marker expression in the non-neural ectoderm, while ectopic expression of Dlx3 or GATA2 in the neural plate suppresses neural plate, border and crest markers. Overexpression of Dlx3 (but not GATA2) in the neural plate is sufficient to induce different non-neural markers in a signaling-dependent manner, with epidermal markers being induced in the presence, and panplacodal markers in the absence, of BMP signaling. Taken together, these findings demonstrate a non-neural versus neural origin of placodes and neural crest, respectively, strongly implicate Dlx3 in the regulation of non-neural competence, and show that GATA2 contributes to non-neural competence but is not sufficient to promote it ectopically.     

Structural studies of the interaction between ubiquitin family proteins and proteasome subunit S5a

The 26S proteasome is essential for the proteolysis of proteins that have been covalently modified by the attachment of polyubiquitinated chains. Although the 20S core particle performs the degradation, the 19S regulatory cap complex is responsible for recognition of polyubiquitinated substrates. We have focused on how the S5a component of the 19S complex interacts with different ubiquitin-like (ubl) modules, to advance our understanding of how polyubiquitinated proteins are targeted to the proteasome. To achieve this, we have determined the solution structure of the ubl domain of hPLIC-2 and obtained a structural model of hHR23a by using NMR spectroscopy and homology modeling. We have also compared the S5a binding properties of ubiquitin, SUMO-1, and the ubl domains of hPLIC-2 and hHR23a and have identified the residues on their respective S5a contact surfaces. We provide evidence that the S5a-binding surface on the ubl domain of hPLIC-2 is required for its interaction with the proteasome. This study provides structural insights into protein recognition by the proteasome, and illustrates how the protein surface of a commonly utilized fold has highly evolved for various biological roles.     

Microbial community associated with the colonial ascidian Cystodytes dellechiajei

The ascidian Cystodytes dellechiajei (Della Valle, 1877) (phylum Chordata, class Ascidiacea, family Polycitoridae) is a colonial tunicate that inhabits benthic rock environments in the Atlantic, Pacific and Indian Oceans, as well as the Mediterranean Sea. Its life cycle has two phases, the adult sessile colony and the free-living larva. Both adult zooids and larvae are surrounded by a protective tunic that contains several eukaryotic cell lines, is composed mainly of acidic mucopolysacharides associated with collagen and elastin-like proteins, and is covered by a thin cuticle. The microbiota associated with the tunic tissues of adult colonies and larva of C. dellechiajei has been examined by optical, confocal and electron microscopy and by fluorescence in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), and 16S rRNA gene clone library analysis. Microscopy analyses indicated the presence inside the tunic, both for the adult and the larva, of a dense community of Bacteria while only the external surface of colony cuticle was colonized by diatoms, rodophyte algae and prokaryotic-like epiphytes. Transmission electron microscopy showed tunic eukaryotic cells that were engulfing and lysing bacteria. 16S rRNA gene analyses (DGGE and clone libraries) and FISH indicated that the community inside the tunic tissues of the adults and larvae was dominated by Alphaproteobacteria. Bacteria belonging to the phyla Gammaproteobacteria and Bacteroidetes were also detected in the adults. Many of the 16S rRNA gene sequences in the tunic tissues were related to known aerobic anoxygenic phototrophs (AAP), like Roseobacter sp. and Erythrobacter sp. In order to check whether the gene pufM, coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis, was being expressed inside the ascidian tissues, two libraries, one for an adult colony and one for larva, of cDNA from the expressed pufM gene were also constructed. The sequences most frequently (64% for colony and 67% for larva) retrieved from these libraries presented > 90% aa identity with the pufM gene product of the Roseobacter-like group, a cluster of AAP widely detected in marine planktonic environments.     

Chromosome damage and aneuploidy detected by interphase multicolour FISH in benzene-exposed shale oil workers

A multicolour tandem-labelling fluorescence in situ hybridization (FISH) procedure was used to detect chromosome alterations in peripheral blood cells of a group of Estonian petrochemistry workers. Twelve workers employed in benzene production and five cokery workers, together with eight unexposed rural controls, were enrolled in the study. The methodology employed, based on the in situ hybridization of adjacent centromeric and pericentromeric regions, allowed the simultaneous detection of both chromosome breakage, involving damage-prone pericentromeric regions, and hyperploidy in interphase cells. Blood smears from all subjects were hybridized with chromosome 1 specific probes, in order to detect genotoxic damage in circulating lymphocytes and granulocytes. Moreover, lymphocyte cultures were established, harvested 48 h following mitogen stimulation and hybridized with the tandem chromosomes 1 and 9 probes. No significant difference in the incidence of breakage was detected in the nucleated cells of blood smears of exposed vs. control subjects. In contrast, modest but significantly increased frequencies of breakage affecting both chromosomes 1 and 9 were observed in the cultured lymphocytes of the benzene-exposed workers compared to the unexposed controls, suggesting an expression of premutagenic lesions during the S-phase in vitro. Across the entire study group, the frequencies of breakage affecting chromosomes 1 and 9 in the stimulated lymphocytes were highly intercorrelated (p < 0.001). No significant difference was found in the incidence of hyperploidy among the study groups, although a tendency to higher values was observed in benzene-exposed workers. Although the relatively small size of the study groups does not allow firm conclusions on the role of occupational exposure, the observed patterns are suggestive of effects in the benzene-exposed workers. This work also shows that tandem labelling FISH can be usefully applied in human biomonitoring, allowing the simultaneous detection of both hyperploidy and chromosome breakage at interphase in different cell types.