Intracellular and Extracellular pH and Ca Are Bound to Control Mitosis in the Early Sea Urchin Embryo via ERK and MPF Activities

Studies aiming to predict the impact on marine life of ocean acidification and of altered salinity have shown altered development in various species including sea urchins. We have analyzed how external Na, Ca, pH and bicarbonate control the first mitotic divisions of sea urchin embryos. Intracellular free Ca (Ca_i) and pH (pH_i) and the activities of the MAP kinase ERK and of MPF regulate mitosis in various types of cells including oocytes and early embryos. We found that intracellular acidification of fertilized eggs by Na-acetate induces a huge activation of ERK at time of mitosis. This also stops the cell cycle and leads to cell death, which can be bypassed by treatment with the MEK inhibitor U0126. Similar intracellular acidification induced in external medium containing low sodium or 5-(N-Methyl-N-isobutyl) amiloride, an inhibitor of the Na⁺/H⁺ exchanger, also stops the cell cycle and leads to cell death. In that case, an increase in Ca_i and in the phosphorylation of tyr-cdc2 occurs during mitosis, modifications that depend on external Ca. Our results indicate that the levels of pH_i and Ca_i determine accurate levels of Ptyr-Cdc2 and P-ERK capable of ensuring progression through the first mitotic cycles. These intracellular parameters rely on external Ca, Na and bicarbonate, alterations of which during climate changes could act synergistically to perturb the early marine life.     

Expression and subcellular localization of a 35-kDa carbonic anhydrase IV in a human pancreatic ductal cell line (Capan-1).

The high intraluminal concentrations of HCO(3)(-) in the human pancreatic ducts have suggested the existence of a membrane protein supplying the Cl(-)/HCO(3)(-) exchanger. Membrane-bound carbonic anhydrase IV (CA IV) is one of the potential candidates for this protein. The difficulties in isolating human pancreatic ducts have led the authors to study the molecular mechanisms of HCO(3)(-) secretion in cancerous cell lines. In this work, we have characterized the CA IV expressed in Capan-1 cells. A 35-kDa CA IV was detected in cell homogenates and purified plasma membranes. Treatment of purified plasma membranes with phosphatidylinositol-phospholipase-C indicated that this CA IV was not anchored by a glycosylphosphatidylinositol (GPI). In contrast, its detection on purified plasma membranes by an antibody specifically directed against the carboxyl terminus of human immature GPI-anchored CA IV indicated that it was anchored by a C-terminal hydrophobic segment. Immunoelectron microscopy and double-labeling immunofluorescence revealed that this CA IV was present on apical plasma membranes, and in the rough endoplasmic reticulum, the endoplasmic reticulum-Golgi intermediate compartment, the Golgi complex, and secretory granules, suggesting its transport via the classical biosynthesis/secretory pathway. The expression in Capan-1 cells of a 35-kDa CA IV anchored in the apical plasma membrane through a hydrophobic segment, as is the case in the healthy human pancreas, should make the study of its role in pancreatic HCO(3)(-) secretion easier.     

Temperature regulation in a burrow-nesting tropical seabird,the Wedge-tailed Shearwater (Puffinus pacificus)

Summary At low air temperatures (2.3–13.9°C), Wedge-tailed Shearwaters (Puffinus pacificus) shivered and their oxygen consumption increased to as much as 283% of the mean value (0.77 ml O₂/g·h) within the thermoneutral zone of air temperature (23–34°C). The minimal thermal conductance of the tissues and plumage was similar to the value predicted from the body mass (320.5 g). The oxygen consumption of the birds within their thermoneutral zone was lower than predictions based on body mass. At elevated air temperatures, the shearwaters panted at respiratory frequencies as high as 260 respirations/min; maximal respiratory frequencies were not invoked until the birds had become hyperthermic. During exposure to a hot environment, the oxygen consumption of the birds increased and in most instances the shearwaters were not able to lose heat equivalent to their concurrent metabolic heat production.Symbols and abbreviations BMR basal metabolic rate - C _total total thermal conductance - f respiratory frequency - TEWL total evaporative water loss - T _st stomach temperature - T _re rectal temperature     

Detergent solubilization of the interleukin 1 receptor

Interleukin 1 (IL 1) receptors were solubilized from membranes prepared from murine EL-4 thymoma cells with the zwitterionic detergent 3[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS). Binding of IL 1 to the solubilized receptor was detected by a polyethylene glycol (PEG) precipitation procedure. Concentrations of CHAPS from 4 to 8 mM were effective in solubilizing the IL 1 receptor. At 10 mM CHAPS, there was some loss in binding activity, whereas 2 mM CHAPS was completely ineffective in solubilizing the receptor. Detergent concentrations of 4 mM were routinely used. The solubilized receptor retains the ability to bind 125I-IL 1 in a specific and saturable manner. Scatchard analysis reveals a single type of high affinity binding site having an apparent dissociation constant (KD) of approximately 1.2 X 10(-10) M. Nearly identical KD values are observed for membrane fractions. There are approximately 400 to 500 fmol receptor/mg protein in the detergent extract, corresponding to a two- to threefold enrichment in the Bmax observed for membranes. There is no loss in receptor activity as determined by complete recovery of the total number of binding sites from membranes after solubilization. Binding kinetics show that apparent steady state for the solubilized receptor is reached after 60 min at 37 degrees C. The binding of 125I-IL 1 is essentially irreversible because relatively little bound ligand can be dissociated from the receptor on the addition of excess unlabeled IL 1 at 37 degrees C. Both human IL 1 alpha and IL 1 beta compete for binding of 125I-IL 1 to the soluble receptor, confirming that IL 1 alpha and IL 1 beta bind to the same receptor. Other recombinant proteins, including interferon-alpha A, interferon-gamma, and interleukin 2 have no inhibitory effect.     

Length, breadth, and elongation of avian eggs from the tables of Sch?nwetter

Summary UsingSchönwetter's data base regression equations are derived expressing egg length and egg breadth as a function of egg mass for Passerines (n=3929) and non-Passerines (n=3217). For both groups these show a variation around the mean which is twice as large for length as for breadth. The average elongation (length/breadth) ist presented for 27 orders ranging from 1.61 in Apterygiformes and Gaviiformes to 1.21 in Strigiformes as well as examples of a few families where elongation increases or decreases as egg mass becomes larger. Egg mass can be estimated from the relationship where egg mass=k(LB²). Mean values, SD, and range of k for both groups are given, but for any particular species are best derived from the dimensions of L, B, and egg mass inSchönwetter's tables.

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Länge, Breite und Form der Vogeleier auf der Grundlage der Tabellen vonSchönwetter

Zusammenfassung Regressionsgleichungen für Eilänge und Eibreite als Funktion der Eimasse ergeben für Passeres (3929 Arten) und Non-Passeres (3217 Arten) eine Streuung um den Mittelwert, die für Länge doppelt so hoch wie für die Breite ist. Das Verhältnis Länge: Breite reicht bei 27 Ordnungen von 1.61 bei Apterygiformes und Gaviiformes bis 1.21 bei den Strigiformes. In Beispielen für einzelne Familien steigt oder fällt der Wert mit zunehmender Eimasse. Letztere kann bestimmt werden gemäß k · (L · B²), wobei k eine Konstante darstellt. Mittelwerte, Standardabweichung und Konstante werden für Passeriformes und Non-Passeriformes angegeben, doch für einzelne Arten hält man sich am besten an die Werte beiSchönwetter.

     

Lysosomal hydrolase activity in chorionic villi and embryonic cells in culture

Summary Fourteen lysosomal enzymes were compared in 20 cultured cell lines from chorionic biopsy and corresponding embryonic tissue after voluntary abortions. Enzymatic expression appears to be similar in cultured cells from both sources with some slightly higher levels for chorionic villi. We stress the importance of culturing chorionic villi especially in the case of enzymes (-L-iduronidase) or diseases (I cell disease) whose expression is unusual in fresh trophoblast tissue.     

Combined use of111In-labeled pentetreotide and three-step immunoscintigraphy with antichromogranin a monoclonal antibody in the diagnosis of pituitary adenomas

For various pituitary adenomas, it has been demonstrated that somatostatin receptor can be present. Pilot studies have shown that radio-indium labeled pentetreotide allows very good scintigraphic localization of somatostatin receptor-bearing cell masses. Recently, the presence of CgA in pituitary adenomas has also been demonstrated. MAb A11, raised against CgA, has been successfully used with a three-step ISG for the diagnosis of neuroendocrine tumors. Therefore the combined use of three-step ISG with MAb A11 and radiolabeled somatostatin can be useful in the diagnosis of pituitary adenomas. Twelve patients, 5 secreting (group A) and 7 nonsecreting (group B) pituitary adenomas, were enrolled in the study. All patients underwent three-step ISG, and, 2 wk later, scintigraphy with¹¹¹In-labeled pentetreotide (Octreoscan). Three-step ISG consisted of iv injection of 1 mg of biotinylated MAb A11 (first step), followed by 10 mg of avidin (second step) and [^99mTc]PnAO-biotin (third step). Tomographic imaging were acquired for three-step ISG and Octreoscan at 2 and 4 h after radiotracer injection, respectively. The results are the following: 2 patients of group A (secreting tumors) had a positive three-step ISG, whereas all the patients but one of the same group had a positive pentetreotide study; all the patients of group B (nonsecreting tumors) had a positive three-step ISG and 4 had a positive pentetreotide scintigraphy. These data suggest the utility of the combined use of these techniques for a better diagnosis of pituitary adenomas.     

The distribution of coastal fish eDNA sequences in the Anthropocene

Aim

Coastal fishes have a fundamental role in marine ecosystem functioning and contributions to people, but face increasing threats due to climate change, habitat degradation and overexploitation. The extent to which human pressures are impacting coastal fish biodiversity in comparison with geographic and environmental factors at large spatial scale is still under scrutiny. Here, we took advantage of environmental DNA (eDNA) metabarcoding to investigate the relationship between fish biodiversity, including taxonomic and genetic components, and environmental but also socio-economic factors.

Location

Tropical, temperate and polar coastal areas.

Time period

Present day.

Major taxa studied

Marine fishes.

Methods

We analysed fish eDNA in 263 stations (samples) in 68 sites distributed across polar, temperate and tropical regions. We modelled the effect of environmental, geographic and socio-economic factors on α- and β-diversity. We then computed the partial effect of each factor on several fish biodiversity components using taxonomic molecular units (MOTU) and genetic sequences. We also investigated the relationship between fish genetic α- and β-diversity measured from our barcodes, and phylogenetic but also functional diversity.

Results

We show that fish eDNA MOTU and sequence α- and β-diversity have the strongest correlation with environmental factors on coastal ecosystems worldwide. However, our models also reveal a negative correlation between biodiversity and human dependence on marine ecosystems. In areas with high dependence, diversity of all fish, cryptobenthic fish and large fish MOTUs declined steeply. Finally, we show that a sequence diversity index, accounting for genetic distance between pairs of MOTUs, within and between communities, is a reliable proxy of phylogenetic and functional diversity.

Main conclusions

Together, our results demonstrate that short eDNA sequences can be used to assess climate and direct human impacts on marine biodiversity at large scale in the Anthropocene and can further be extended to investigate biodiversity in its phylogenetic and functional dimensions.     

Dose dependent accretion of docosahexaenoic acid (DHA) in cardiac membranes of rats fed egg yolk powder enriched in DHA.

We tested the hypothesis that enrichment of the diet with docosahexaenoic acid (DHA) enriched egg yolk powder could modify specifically the (n-3) fatty acids content of rat plasma, red blood cells and heart membranes. Dose-dependent effect of DHA was studied in rats supplemented during 4 weeks. Three groups of adult male rats, DHA10, DHA35 and DHA60 (n = 5 each), had their diet supplemented with 10 mg, 35 mg or 60 mg DHA/kg body weight/day, respectively. Fatty acid composition of membranes and plasma lipids were determined. A significant dose-dependent increase in DHA was observed in all three types of samples. Arachidonic acid (AA) levels did not change in heart and red blood cell membranes whereas it increased significantly in plasma with the DHA35 diet. These results contrast with that previously reported for fish oil supplementation where a decrease in AA levels was reported. Hence, DHA enriched egg yolk supplementation leads to a specific accretion of DHA without competition on AA status.     

Aerobic degradation of polychlorinated biphenyls by Alcaligenes sp. JB1: metabolites and enzymes

In contrast to the degradation of penta-and hexachlorobiphenyls in chemostat cultures, the metabolism of PCBs by Alcaligenes sp. JB1 was shown to be restricted to PCBs with up to four chlorine substituents in resting-cell assays. Among these, the PCB congeners containing ortho chlorine substituents on both phenyl rings were found to be least degraded. Monochloro-benzoates and dichlorobenzoates were detected as metabolites. Resting cell assays with chlorobenzoates showed that JB1 could metabolize all three monochlorobenzoates and dichlorobenzoates containing only meta and para chlorine substituents, but not dichlorobenzoates possessing an ortho chlorine substituent. In enzyme activity assays, meta cleaving 2,3-dihydroxybiphenyl 1,2-dioxygenase and catechol 2,3-dioxygenase activities were constitutive, whereas benzoate dioxygenase and ortho cleaving catechol 1,2-dioxygenase activities were induced by their substrates. No activity was found for pyrocatechase II, the enzyme that is specific for chlorocatechols. The data suggest that complete mineralization of PCBs with three or more chlorine substituents by Alcaligenes sp. JB1 is unlikely.Abbreviations PCB polychlorinated biphenyls - CBA chlorobenzoate - D di - Tr tri - Te tetra - Pe penta- - H hexa