High‐density areas for harbor porpoises (Phocoena phocoena) identified by satellite tracking

The population status of harbor porpoises has been of concern for several years, and the establishment of Marine Protected Areas (MPAs) has been suggested as a method to protect the harbor porpoise (Phocoena phocoena, Linneaus 1758) and other small cetaceans. In order to designate MPAs, high‐density areas for the species must be identified. Spatial distribution of small cetaceans is usually assessed from ship or aerial surveys. As a potentially more accurate alternative, this study examined the movements and area preferences of 64 harbor porpoises, satellite tagged between 1997 and 2007, in order to determine the distribution in the North Sea, the western Baltic, and the waters in between. Results show that harbor porpoises are not evenly distributed, but congregate in nine high‐density areas within the study area. Several of these areas are subject to significant seasonal variation. The study found no differences in the home range size of males and females, but immature harbor porpoises have larger home ranges than mature porpoises. The use of satellite telemetry for identifying areas of high harbor porpoise density can be of key importance when designating MPAs.     

The restriction endonuclease Alu I induces chromosomal aberrations in human peripheral lymphocytes in vitro

The restriction endonuclease Alu I (recognition site AG/CT) produces chromosomal aberrations in isolated human peripheral lymphocytes in vitro. The aberrations are of the chromosome-type when the cells are treated in G1 and of the chromatid-type when the cells are treated in late S, early G2. Additional treatment with ammonium sulphate leads to higher aberration frequencies than treatment with Alu I alone.     

Lack of AMPKalpha2 enhances pyruvate dehydrogenase activity during exercise

5'-AMP-activated protein kinase (AMPK) was recently suggested to regulate pyruvate dehydrogenase (PDH) activity and thus pyruvate entry into the mitochondrion. We aimed to provide evidence for a direct link between AMPK and PDH in resting and metabolically challenged (exercised) skeletal muscle. Compared with rest, treadmill running increased AMPKalpha1 activity in alpha(2)KO mice (90%, P < 0.01) and increased AMPKalpha2 activity in wild-type (WT) mice (110%, P < 0.05), leading to increased AMPKalpha Thr(172) (WT: 40%, alpha(2)KO: 100%, P < 0.01) and ACCbeta Ser(227) phosphorylation (WT: 70%, alpha(2)KO: 210%, P < 0.01). Compared with rest, exercise significantly induced PDH-E(1)alpha site 1 (WT: 20%, alpha(2)KO: 62%, P < 0.01) and site 2 (only alpha(2)KO: 83%, P < 0.01) dephosphorylation and PDH(a) [ approximately 200% in both genotypes (P < 0.01)]. Compared with WT, PDH dephosphorylation and activation was markedly enhanced in the alpha(2)KO mice both at rest and during exercise. The increased PDH(a) activity during exercise was associated with elevated glycolytic flux, and muscles from the alpha(2)KO mice displayed marked lactate accumulation and deranged energy homeostasis. Whereas mitochondrial DNA content was normal, the expression of several mitochondrial proteins was significantly decreased in muscle of alpha(2)KO mice. In isolated resting EDL muscles, activation of AMPK signaling by AICAR did not change PDH-E(1)alpha phosphorylation in either genotype. PDH is activated in mouse skeletal muscle in response to exercise and is independent of AMPKalpha2 expression. During exercise, alpha(2)KO muscles display deranged energy homeostasis despite enhanced glycolytic flux and PDH(a) activity. This may be linked to decreased mitochondrial oxidative capacity.     

Fatty acids increase paracellular absorption of aluminium across Caco-2 cell monolayers

Passive paracellular absorption, regulated by tight junctions (TJs), is the main route for absorption of poorly absorbed hydrophilic substances. Surface active substances, such as fatty acids, may enhance absorption of these substances by affecting the integrity of TJ and increasing the permeability. It has been suggested that aluminium (Al) absorption occurs mainly by the paracellular route. Herein, we investigated if physiologically relevant exposures of fully differentiated Caco-2 cell monolayers to oleic acid and docosahexaenoic acid (DHA), which are fatty acids common in food, increase absorption of Al and the paracellular marker mannitol. In an Al toxicity test, mannitol and Al absorption through Caco-2 cell monolayers were similarly modulated by Al concentrations between 1 and 30 mM, suggesting that absorption of the two compounds occurred via the same pathways. Exposure of Caco-2 cell monolayers to non-toxic concentrations of Al (2 mM) and ¹⁴C-mannitol in fatty acid emulsions (15 and 30 mM oleic acid, 5 and 10 mM DHA) caused a decreased transepithelial electrical resistance (TEER). Concomitantly, fractional absorption of Al and mannitol, expressed as percentage of apical Al and mannitol retrieved at the basolateral side, increased with increasing dose of fatty acids. Transmission electron microscopy was applied to assess the effect of oleic acid on the morphology of TJ. It was shown that oleic acid caused a less structured morphology of TJ in Caco-2 cell monolayers. Taken together our findings indicate that fatty acids common in food increase the paracellular intestinal absorption of Al. These findings may influence future risk assessment of human Al exposure.     

Proteome analysis reveals novel proteins associated with proliferation and differentiation of the colorectal cancer cell line Caco-2

Here, we describe a proteomics approach to study protein expression changes in differentiating Caco-2 cells. Caco-2 is a colorectal carcinoma cell line, which upon differentiation loses its tumorigenic phenotype and displays characteristics of mature enterocytes, including brush borders with microvilli. Cells were grown in culture flasks and harvested at different stages of differentiation (days post-confluence: -3, 0, 3, 7, 10, 14, and 18). Two-dimensional gel electrophoresis was used to analyse proteome changes. Approximately 1400 protein spots were detected within the Caco-2 proteome, within the pH 4-7 range. Two-dimensional gel electrophoresis allowed for the detection of 18 proteins from which the levels of expression were found to be associated with differentiation. Of these proteins, 11 were identified by means of MALDI-TOF or NANO-ESI-MS/MS mass spectrometry and include liver fatty acid binding protein (FABL), three forms of alpha-enolase (ENOA), nucleoside diphosphate kinase A (NDKA), cofilin-1 (COF1), translationally controlled tumour protein (TCTP), mitochondrial 60-kDa heat shock protein (CH60), probable protein disulfide isomerase (ER60), creatine kinase B (KCRB), and glutathione S-transferase alpha (GTA1). Thus, proteomics revealed that the differentiation-related change in phenotype of Caco-2 involves changes in a variety of distinct biochemical pathways. Some of these proteins have not been shown before to be associated with Caco-2 differentiation (ER60; COF1; CH60; NDKA; TCTP and ENOA). Therefore, processes related to protein folding and disulfide bridge formation, cytoskeleton formation and maintenance, nucleotide metabolism, glycolysis as well as tumorigenesis-associated proteins may be involved in Caco-2 differentiation. Changes in the expression of CH60, TCTP, GTA1, NDKA, and FABL have also been reported to be associated with in vivo colon carcinogenesis. These findings illustrate that a combination of proteomics and cell culture is a useful approach to find markers for Caco-2 differentiation, which could contribute to the comprehension of the process of colon carcinogenesis.     

Crystal structure of Zn(trz)Cl (trz = 11,2,4,-triazolato); a layered compound with triply bridging triazolato groups

ZnCl₂ reacts with 1,2,4-1H-triazole to afford Zn(trz)Cl. A spontaneous deprotonation of Htrz occurs. The crystal structure of Zn(trz)Cl has been solved. The compound crystallizes in the space group P2₁/n. The lattice parameters are a = 8.863(4), B = 9.762(4), C = 6.146(3) Å, β = 99.56(10)°, with Z = 4. The 1,2,4-triazolato bridges three zinc atoms through its three nitrogen atoms, affording a layered structure. The zinc atom is in an N₃Cl tetrahedral coordination. The layers are not planar, but rather corrugated. The chlorine atoms point to either side of the layers, and play the role of spacers. The shortest interlayer ZnZn separation is 5.701 Å.     

Nickel resistance in Escherichia coli V38 is dependent on the concentration used for induction

Strain Escherichia coli V38 resistant to 4 mM NiCl₂ was isolated from the city sewage sludge. It showed low nickel accumulation by cells and nickel ion efflux. Cells were pregrown (induced) overnight in the presence of Ni²⁺, then the culture was kept on ice for 20–30 min and transferred to 37°C for further incubation. When the Ni²⁺ concentration during growth was the same as during incubation, there was no noticeable accumulation of Ni²⁺. When the Ni²⁺ concentration during incubation was higher than that used for induction, uptake of ⁶³Ni²⁺ and delayed efflux were seen. The uptake and delay of both efflux and growth were directly proportional to the difference between the concentrations used for induction and incubation. Active nickel ion uptake was seen in cells taken from cultures in the delayed efflux period.     

Continuous fluorescence assay for lecithin:cholesterol acyltransferase using a water-soluble phosphatidylcholine.

A water-soluble fluorescent phosphatidylcholine, 1,2-bis[4-(1-pyreno-butanoyl]-sn-glycero-3-phosphocholine (DPybPC) has been used to develop a sensitive, continuous assay for pure lecithin:cholesterol acyltransferase (LCAT) in solution. The monomeric substrate allowed us to examine the reaction of LCAT in the absence of a lipid/water interface in terms of the sensitivity of the enzymatic reaction to anions, ionic strength, apolipoproteins A-I and A-II, and a series of lysophosphatidylcholines and fatty acids. In contrast to the reaction of LCAT with aggregated phosphatidylcholines, the reaction of DPybPC with LCAT was not significantly affected by anions, ionic strength, nor apolipoproteins, indicating that these are only effectors of the interfacial reaction. Lysophosphatidylcholines and fatty acids inhibited LCAT in a chain-length-dependent manner below the critical micellar concentrations of these amphiphiles, indicating that the products of the LCAT reaction can bind to the enzyme and affect its kinetics even in the absence of an interface.     

The role of shaded cocoa plantations in the maintenance of epiphytic orchids and their interactions with phorophytes

生境丧失和破碎化是热带森林生物多样性的主要威胁。遮荫的可可种植园(SCP)等农业生态系统为热带森林生物群提供了庇护。然而,在这些转化后的生境中是否还维持种间生态的相互作用,目前尚鲜为人知。我们评定附生兰花群落的多样性、繁殖状态和光合代谢(CAM或C₃),以及与热带雨林(TRF)相比,它们与SCP中寄主树种(附生植物)之间的相互作用。在墨西哥东南部,对TRF和SCP中各三个采样地点进行研究。每个采样地点建立了4个400平方米的样地,调查记录所有兰花及其附生植物。我们依据花/果实(或残体)是否存在来确定每个兰花个体的繁殖(成体)或非繁殖(幼体)状态,并根据文献确定每种兰花的光合作用途径。我们采用真正的分集和生态网络的方法分别分析兰花的多样性以及兰科与附生植物间的相互作用。我们一共记录了47个兰花种的607个个体。在TRF (19个有效物种)中的兰花多样性高于SCP (11个有效物种),两个生境之间仅共享7个物种。SCP (53%)中的CAM兰花物种比TRF (14%)更常见。在群落水平上,SCP维持了非生殖兰花和生殖兰花的比例以及TRF兰科附生植物网络的嵌套结构和特异化水平。然而,SCP中仅保留一部分的TRF附生兰花,突显出保护TRF的重要性。尽管存在这种差异,诸如SCP类型的遮荫农业生态系统仍然可以维持天然林的一些多样性和功能,因为SCP附生兰花群落主要由CAM物种组成,其附生植物构成了一个嵌套的相互作用网络,对干扰形成了更强的抗性。     

Comparing diversity levels in environmental samples: DNA sequence capture and metabarcoding approaches using 18S and COI genes

Environmental DNA studies targeting multiple taxa using metabarcoding provide remarkable insights into levels of species diversity in any habitat. The main drawbacks are the presence of primer bias and difficulty in identifying rare species. We tested a DNA sequence‐capture method in parallel with the metabarcoding approach to reveal possible advantages of one method over the other. Both approaches were performed using the same eDNA samples and the same 18S and COI regions, followed by high throughput sequencing. Metabarcoded eDNA libraries were PCR amplified with one primer pair from 18S and COI genes. DNA sequence‐capture libraries were enriched with 3,639 baits targeting the same gene regions. We tested amplicon sequence variants (ASVs) and operational taxonomic units (OTUs) in silico approaches for both markers and methods, using for this purpose the metabarcoding data set. ASVs methods uncovered more species for the COI gene, whereas the opposite occurred for the 18S gene, suggesting that clustering reads into OTUs could bias diversity richness especially using 18S with relaxed thresholds. Additionally, metabarcoding and DNA sequence‐capture recovered 80%–90% of the control sample species. DNA sequence‐capture was 8x more expensive, nonetheless it identified 1.5x more species for COI and 13x more genera for 18S than metabarcoding. Both approaches offer reliable results, sharing ca. 40% species and 72% families and retrieve more taxa when nuclear and mitochondrial markers are combined. eDNA metabarcoding is quite well established and low‐cost, whereas DNA‐sequence capture for biodiversity assessment is still in its infancy, is more time‐consuming but provides more taxonomic assignments.