Effects of decomposition and storage conditions on the δ13C and δ15N isotope values of killer whale (Orcinus orca) skin and blubber tissues

Several different factors in the collection and preservation of whale skin and blubber samples were examined to determine their effect on the results obtained by stable nitrogen and carbon isotope (δ¹⁵N and δ¹³C) analysis. Samples of wet killer whale skin retained their original stable isotope values for up to 14 d at 4°C or lower. However, decomposition significantly changed the δ¹⁵N value within 3 d at 20°C. Storage at ?20°C was as effective as ?80°C for the preservation of skin and blubber samples for stable isotope analysis for at least a year. By contrast, once a skin sample had been freeze‐dried and lipid extracted, the stable isotope values did not change significantly when it was stored dry at room temperature for at least 12 mo. Preservation of whale skin samples for a month in DMSO‐salt solution, frozen or at room temperature, did not significantly change the δ¹⁵N and δ¹³C values of lipid extracted tissues, although the slight changes seen could influence results of a study if only small changes are expected.     

Computational modelling and analysis of mechanical conditions on cell locomotion and cell–cell interaction

Between other parameters, cell migration is partially guided by the mechanical properties of its substrate. Although many experimental works have been developed to understand the effect of substrate mechanical properties on cell migration, accurate 3D cell locomotion models have not been presented yet. In this paper, we present a novel 3D model for cells migration. In the presented model, we assume that a cell follows two main processes: in the first process, it senses its interface with the substrate to determine the migration direction and in the second process, it exerts subsequent forces to move. In the presented model, cell traction forces are considered to depend on cell internal deformation during the sensing step. A random protrusion force is also considered which may change cell migration direction and/or speed. The presented model was applied for many cases of migration of the cells. The obtained results show high agreement with the available experimental and numerical data.     

HIV-1 Tat protein induces glial cell autophagy through enhancement of BAG3 protein levels

BAG3 protein has been described as an anti-apoptotic and pro-autophagic factor in several neoplastic and normal cells. We previously demonstrated that BAG3 expression is elevated upon HIV-1 infection of glial and T lymphocyte cells. Among HIV-1 proteins, Tat is highly involved in regulating host cell response to viral infection. Therefore, we investigated the possible role of Tat protein in modulating BAG3 protein levels and the autophagic process itself. In this report, we show that transfection with Tat raises BAG3 levels in glioblastoma cells. Moreover, BAG3 silencing results in highly reducing Tat- induced levels of LC3-II and increasing the appearance of sub G0/G1 apoptotic cells, in keeping with the reported role of BAG3 in modulating the autophagy/apoptosis balance. These results demonstrate for the first time that Tat protein is able to stimulate autophagy through increasing BAG3 levels in human glial cells.     

The TRAF3 adaptor protein drives proliferation of anaplastic large cell lymphoma cells by regulating multiple signaling pathways

T cells devoid of tumor necrosis factor receptor associated factor-3 (Traf3) exhibit decreased proliferation, sensitivity to apoptosis, and an improper response to antigen challenge. We therefore hypothesized that TRAF3 is critical to the growth of malignant T cells. By suppressing TRAF3 protein in different cancerous T cells, we found that anaplastic large cell lymphoma (ALCL) cells require TRAF3 for proliferation. Since reducing TRAF3 results in aberrant activation of the noncanonical nuclear factor-κB (NF-κB) pathway, we prevented noncanonical NF-κB signaling by suppressing RelB together with TRAF3. This revealed that TRAF3 regulates proliferation independent of the noncanonical NF-κB pathway. However, suppression of NF-κB-inducing kinase (NIK) along with TRAF3 showed that high levels of NIK have a partial role in blocking cell cycle progression. Further investigation into the mechanism by which TRAF3 regulates cell division demonstrated that TRAF3 is essential for continued PI3K/AKT and JAK/STAT signaling. In addition, we found that while NIK is dispensable for controlling JAK/STAT activity, NIK is critical to regulating the PI3K/AKT pathway. Analysis of the phosphatase and tensin homolog (PTEN) showed that NIK modulates PI3K/AKT signaling by altering the localization of PTEN. Together our findings implicate TRAF3 as a positive regulator of the PI3K/AKT and JAK/STAT pathways and reveal a novel function for NIK in controlling PI3K/AKT activity. These results provide further insight into the role of TRAF3 and NIK in T cell malignancies and indicate that TRAF3 differentially governs the growth of B and T cell cancers.     

The Intrasectional Chemotaxonomic Placement of Hypericum elegans Stephan ex Willd. Inferred from the Essential‐Oil Chemical Composition

Here we report, for the first time, the results of detailed GC and GC/MS analyses of the essential oil of a rare taxon in Serbia, Hypericum elegans Stephan ex Willd . One hundred and sixty two constituents identified accounted for 98.6% of the oil. The major components of the oil were undecane (31.9%), α‐pinene (16.7%), nonane (6.1%), bicyclogermacrene (5.8%), 2‐methyloctane (3.7%), and germacrene D (3.6%). Non‐terpenoids as chemotaxonomic markers constituted the main fraction of H. elegans oil, whereby n‐alkanes were the most abundant contributors of this fraction. Based on these results and previously published ones, we performed an intrasectional multivariate statistical comparison of corresponding essential‐oil chemical compositions. Principal component analysis (PCA) and agglomerative hierarchical clustering (AHC) of the data on the volatile profiles of section Hypericum taxa revealed that H. elegans either represents an oil chemotype of its own (AHC) or could be considered related to H. perforatum (PCA).     

Extensive and Modular Intrinsically Disordered Segments in C. elegans TTN-1 and Implications in Filament Binding, Elasticity and Oblique Striation

TTN-1, a titin like protein in Caenorhabditis elegans, is encoded by a single gene and consists of multiple Ig and fibronectin 3 domains, a protein kinase domain and several regions containing tandem short repeat sequences. We have characterized TTN-1's sarcomere distribution, protein interaction with key myofibrillar proteins as well as the conformation malleability of representative motifs of five classes of short repeats. We report that two antibodies developed to portions of TTN-1 detect an ∼ 2-MDa polypeptide on Western blots. In addition, by immunofluorescence staining, both of these antibodies localize to the I-band and may extend into the outer edge of the A-band in the obliquely striated muscle of the nematode. Six different 300-residue segments of TTN-1 were shown to variously interact with actin and/or myosin in vitro. Conformations of synthetic peptides of representative copies of each of the five classes of repeats—39-mer PEVT, 51-mer CEEEI, 42-mer AAPLE, 32-mer BLUE and 30-mer DispRep—were investigated by circular dichroism at different temperatures, ionic strengths and solvent polarities. The PEVT, CEEEI, DispRep and AAPLE peptides display a combination of a polyproline II helix and an unordered structure in aqueous solution and convert in trifluoroethanol to α-helix (PEVT, CEEEI, DispRep) and β-turn (AAPLE) structures, respectively. The octads in BLUE motifs form unstable α-helix-like structures coils in aqueous solution and negligible heptad-based, α-helical coiled-coils. The α-helical structure, as modeled by threading and molecular dynamics simulations, tends to form helical bundles and crosses based on its 8-4-2-2 hydrophobic helical patterns and charge arrays on its surface. Our finding indicates that APPLE, PEVT, CEEEI and DispRep regions are all intrinsically disordered and highly reminiscent of the conformational malleability and elasticity of vertebrate titin PEVK segments. The proposed presence of long, modular and unstable α-helical oligomerization domains in the BLUE region of TTN-1 could bundle TTN-1 and stabilize oblique striation of the sarcomere.     

Protein N-Homocysteinylation Induces the Formation of Toxic Amyloid-Like Protofibrils

Previous works reported that a mild increase in homocysteine level is a risk factor for cardiovascular and neurodegenerative diseases in humans. Homocysteine thiolactone is a cyclic thioester, most of which is produced by an error-editing function of methionyl-tRNA synthetase, causing in vivo post-translational protein modifications by reacting with the ?-amino group of lysine residues. In cells, the rate of homocysteine thiolactone synthesis is strictly dependent on the levels of the precursor metabolite, homocysteine. In this work, using bovine serum albumin as a model, we investigated the impact of N-homocysteinylation on protein conformation as well as its cellular actions. Previous works demonstrated that protein N-homocysteinylation causes enzyme inactivation, protein aggregation, and precipitation. In addition, in the last few years, several pieces of evidence have indicated that protein unfolding and aggregation are crucial events leading to the formation of amyloid fibrils associated with a wide range of human pathologies. For the first time, our results reveal how the low level of protein N-homocysteinylation can induce mild conformational changes leading to the formation of native-like aggregates evolving over time, producing amyloid-like structures. Taking into account the fact that in humans about 70% of circulating homocysteine is N-linked to blood proteins such as serum albumin and hemoglobin, the results reported in this article could have pathophysiological relevance and could contribute to clarify the mechanisms underlying some pathological consequences described in patients affected by hyperhomocysteinemia.     

益坤宁对围绝经期大鼠卵巢细胞凋亡率及caspase-3表达的影响

目的:研究中药益坤宁(yikunning,YKN)对围绝经期大鼠卵巢细胞凋亡率及凋亡相关基因caspase-3基因表达的影响,探讨益坤宁治疗围绝经期综合征的作用机理。方法:选用30只自然衰老的围绝经期雌性大鼠,随机分为中药益坤宁实验组、围绝经期对照组和利维爱(livial)对照组,另选10只青年雌性大鼠作为青年对照组。连续灌胃处理4周后,采用原位脱氧核糖核苷酸末端转移酶介导的缺口末端标记(TUNEL)法检测大鼠卵巢细胞凋亡率,采用逆转录-聚合酶链反应(RT-PCR)和蛋白印迹(Western blot)检测大鼠卵巢中caspase-3 mRNA和蛋白表达。结果:益坤宁组大鼠卵巢细胞凋亡率显著低于围绝经期对照组(P0.01);益坤宁组大鼠卵巢中caspase-3 mRNA和蛋白表达低于围绝经期对照组,高于青年对照组,差异有统计学意义(P0.01)。结论:中药益坤宁通过降低围绝经期大鼠卵巢细胞凋亡率,下调卵巢中凋亡相关基因caspase-3的表达,从而延缓卵巢衰老,这可能是其治疗围绝经期综合征的分子机制之一。     

Suppression of Adipocyte Differentiation by Aldo-keto Reductase 1B3 Acting as Prostaglandin F2�� Synthase

Prostaglandin (PG) F_2α suppresses adipocyte differentiation by inhibiting the function of peroxisome proliferator-activated receptor γ. However, PGF_2α synthase (PGFS) in adipocytes remains to be identified. Here, we studied the expression of members of the aldo-keto reductase (AKR) 1B family acting as PGFS during adipogenesis of mouse 3T3-L1 cells. AKR1B3 mRNA was expressed in preadipocytes, and its level increased about 4-fold at day 1 after initiation of adipocyte differentiation, and then quickly decreased the following day to a level lower than that in the preadipocytes. In contrast, the mRNA levels of Akr1b8 and 1b10 were clearly lower than that level of Akr1b3 in preadipocytes and remained unchanged during adipogenesis. The transient increase in Akr1b3 during adipogenesis was also observed by Western blot analysis. The mRNA for the FP receptor, which is selective for PGF_2α, was also expressed in preadipocytes. Its level increased about 2-fold within 1 h after the initiation of adipocyte differentiation and was maintained at almost the same level throughout adipocyte differentiation. The small interfering RNA for Akr1b3, but not for Akr1b8 or 1b10, suppressed PGF_2α production and enhanced the expression of adipogenic genes such as peroxisome proliferator-activated receptor γ, fatty acid-binding protein 4 (aP2), and stearoyl-CoA desaturase. Moreover, an FP receptor agonist, Fluprostenol, suppressed the expression of those adipogenic genes in 3T3-L1 cells; whereas an FP receptor antagonist, AL-8810, efficiently inhibited the suppression of adipogenesis caused by the endogenous PGF_2α. These results indicate that AKR1B3 acts as the PGFS in adipocytes and that AKR1B3-produced PGF_2α suppressed adipocyte differentiation by acting through FP receptors.