The caecilian amphibian Scolecomorphus kirkii Boulenger as prey of the burrowing asp Atractaspis aterrima Günther: trophic relationships of fossorial vertebrates

A report is given of an adult caecilian, Scolecomorphus kirkii, found in the gut of a specimen of the snake Atractaspis aterrima from the Udzungwa Mountains, Tanzania. Both predator and prey are largely fossorial in soil, and their ecology is poorly known, such that this is the first reported predator of any scolecomorphid caecilian. The caecilian was ingested head first and much of the flesh from the anterior of the specimen had been digested. The prey/predator mass ratio is 0.48. This value is substantially higher than reported for A. aterrima from West Africa, and refutes the notion that this species feeds only on small prey. Most reported predators of caecilians are snakes, and a brief review is presented.     

A systems-level approach for metabolic engineering of yeast cell factories

The generation of novel yeast cell factories for production of high-value industrial biotechnological products relies on three metabolic engineering principles: design, construction, and analysis. In the last two decades, strong efforts have been put on developing faster and more efficient strategies and/or technologies for each one of these principles. For design and construction, three major strategies are described in this review: (1) rational metabolic engineering; (2) inverse metabolic engineering; and (3) evolutionary strategies. Independent of the selected strategy, the process of designing yeast strains involves five decision points: (1) choice of product, (2) choice of chassis, (3) identification of target genes, (4) regulating the expression level of target genes, and (5) network balancing of the target genes. At the construction level, several molecular biology tools have been developed through the concept of synthetic biology and applied for the generation of novel, engineered yeast strains. For comprehensive and quantitative analysis of constructed strains, systems biology tools are commonly used and using a multi-omics approach. Key information about the biological system can be revealed, for example, identification of genetic regulatory mechanisms and competitive pathways, thereby assisting the in silico design of metabolic engineering strategies for improving strain performance. Examples on how systems and synthetic biology brought yeast metabolic engineering closer to industrial biotechnology are described in this review, and these examples should demonstrate the potential of a systems-level approach for fast and efficient generation of yeast cell factories.     

Angiotensin II modulates VEGF-driven angiogenesis by opposing effects of type 1 and type 2 receptor stimulation in the microvascular endothelium

Vascular endothelial growth factor (VEGF) is a main stimulator of pathological vessel formation. Nevertheless, increasing evidence suggests that Angiotensin II (Ang II) can play an augmentory role in this process. We thus analyzed the contribution of the two Ang II receptor types, AT(1)R and AT(2)R, in a mouse model of VEGF-driven angiogenesis, i.e. oxygen-induced proliferative retinopathy. Application of the AT(1)R antagonist telmisartan but not the AT(2)R antagonist PD123,319 largely attenuated the pathological response. A direct effect of Ang II on endothelial cells (EC) was analyzed by assessing angiogenic responses in primary bovine retinal and immortalized rat microvascular EC. Selective stimulation of the AT(1)R by Ang II in the presence of PD123,319 revealed a pro-angiogenic activity which further increased VEGF-driven EC sprouting and migration. In contrast, selective stimulation of the AT(2)R by either CGP42112A or Ang II in the presence of telmisartan inhibited the VEGF-driven angiogenic response. Using specific inhibitors (pertussis toxin, RGS proteins, kinase inhibitors) we identified G(12/13) and G(i) dependent signaling pathways as the mediators of the AT(1)R-induced angiogenesis and the AT(2)R-induced inhibition, respectively. As AT(1)R and AT(2)R stimulation displays opposing effects on the activity of the monomeric GTPase RhoA and pro-angiogenic responses to Ang II and VEGF requires activation of Rho-dependent kinase (ROCK), we conclude that the opposing effects of the Ang II receptors on VEGF-driven angiogenesis converge on the regulation of activity of RhoA-ROCK-dependent EC migration.     

Pyrosequencing as a Method for Grouping of Listeria monocytogenes Strains on the Basis of Single-Nucleotide Polymorphisms in the inlB Gene

By using pyrosequencing (i.e., sequencing by synthesis) 106 strains of different serovars of Listeria monocytogenes were rapidly grouped into four categories based on nucleotide variations at positions 1575 and 1578 of the inlB gene. Strains of serovars 1/2a and 1/2c constituted one group, and strains of serovars 1/2b and 3b constituted another group, whereas serovar 4b strains were separated into two groups.     

Alternative reproductive tactics are associated with sperm performance in invasive round goby from two different salinity environments

During male–male competition, evolution can favor alternative reproductive tactics. This often results in a dominant morph that holds a resource, such as a nest for egg laying, which competes with a smaller sneaker morph that reproduces by stealing fertilizations. The salinity environment can influence male growth rates, for example, via osmoregulatory costs, which in turn may influence the use of sneaker tactics for small males competing for mating opportunities. Salinity can also affect sperm directly; however, little is known of how salinity influences sneaker tactics through sperm performance. We sampled males of the invasive round goby (Neogobius melanostomus) from two environments, a freshwater river and a brackish estuary. This fish has two male morphs: nest‐holding dark males and non‐nest‐holding light males. We examined the role of water salinity of 0, 8, and 16 on sperm performance and found that for estuarine males, a salinity of 0 reduced sperm velocity compared to a salinity of 8 and 16. Riverine males had low velocity in all salinities. Sperm viability also decreased by over 30% in 0 salinity, compared to 8 and 16, for fish from both environments. Gobies produce ejaculate contents in specialized glands that could in theory shield sperm in an adverse environment. However, gland contents did not improve sperm performance in our tests. Body mass and age estimates indicate that riverine males invested more in somatic growth compared to estuarine males. Estuarine light morph males had a high enough gonadosomatic index to indicate sneaker tactics. We propose that when sperm performance is low, such as for the riverine males, sneaker tactics are ineffective and will be selected against or phenotypically suppressed. Instead, we interpret the increased investment in somatic growth found in riverine males as a life‐history decision that is advantageous when defending a nest in the next reproductive season.     

GABA(A) receptor function is regulated by lipid bilayer elasticity

Docosahexaenoic acid (DHA) and other polyunsaturated fatty acids (PUFAs) promote GABA(A) receptor [(3)H]-muscimol binding, and DHA increases the rate of GABA(A) receptor desensitization. Triton X-100, a structurally unrelated amphiphile, similarly promotes [(3)H]-muscimol binding. The mechanism(s) underlying these effects are poorly understood. DHA and Triton X-100, at concentrations that affect GABA(A) receptor function, increase the elasticity of lipid bilayers measured as decreased bilayer stiffness using gramicidin channels as molecular force transducers. We have previously shown that membrane protein function can be regulated by amphiphile-induced changes in bilayer elasticity and hypothesized that GABA(A) receptors could be similarly regulated. We therefore studied the effects of four structurally unrelated amphiphiles that decrease bilayer stiffness (Triton X-100, octyl-beta-glucoside, capsaicin, and DHA) on GABA(A) receptor function in mammalian cells. All the compounds promoted GABA(A) receptor [(3)H]-muscimol binding by increasing the binding capacity of high-affinity binding without affecting the associated equilibrium binding constant. A semiquantitative analysis found a similar quantitative relation between the effects on bilayer stiffness and [(3)H]-muscimol binding. Membrane cholesterol depletion, which also decreases bilayer stiffness, similarly promoted [(3)H]-muscimol binding. In whole-cell voltage-clamp experiments, Triton X-100, octyl-beta-glucoside, capsaicin, and DHA all reduced the peak amplitude of the GABA-induced currents and increased the rate of receptor desensitization. The effects of the amphiphiles did not correlate with the expected changes in monolayer spontaneous curvature. We conclude that GABA(A) receptor function is regulated by lipid bilayer elasticity. PUFAs may generally regulate membrane protein function by affecting the elasticity of the host lipid bilayer.     

Regulation of NF-κB signaling by caspases and MALT1 paracaspase

Caspases are intracellular proteases that are best known for their function in apoptosis signaling. It has become evident that many caspases also function in other signaling pathways that propagate cell proliferation and inflammation, but studies on the inflammatory function of caspases have mainly been limited to caspase-1-mediated cytokine processing. Emerging evidence, however, indicates an important contribution of caspases as mediators or regulators of nuclear factor-κB (NF-κB) signaling, which plays a key role in inflammation and immunity. Much still needs to be learned about the mechanisms that govern the activation and regulation of NF-κB by caspases, and this review provides an update of this area. Whereas apoptosis signaling is dependent on the catalytic activity of caspases, they mainly act as scaffolding platforms for other signaling proteins in the case of NF-κB signaling. Caspase proteolytic activity, however, counteracts the pro-survival function of NF-κB by cleaving specific signaling molecules. A striking exception is the paracaspase mucosa-associated lymphoid tissue 1 (MALT1), whose adaptor and proteolytic activity are both needed to initiate a full blown NF-κB response in antigen-stimulated lymphocytes. Understanding the role of caspases and MALT1 in the regulation of NF-κB signaling is of high interest for therapeutic immunomodulation.     

Hoverflies (Diptera: Syrphidae) benefit from a cultivation of the bioenergy crop Silphium perfoliatum L. (Asteraceae) depending on larval feeding type,landscape composition and crop management

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