Pitfalls of nonstandardized photography in facial plastic surgery patients

The authors tested the hypothesis that certain maneuvers (neck flexion/extension and head protrusion/retrusion) alter the appearance of the submental area, jawline, and melolabial groove. They used a questionnaire survey of 20 na?ve judges who assessed a standardized photograph album of three subjects. The subjects' faces (frontal and lateral views) were photographed in neutral, neck flexion/extension, and head protrusion/retrusion positions. High Kendall coefficients of correlation were observed in 10 of 12 questions evaluating an improvement in jawline definition with neck extension or head protrusion, as well as in 11 of 12 questions assessing decreased submental soft tissue. All questions relating to the melolabial groove had a correlation coefficient of less than 0.70. Small changes in patient positioning during photodocumentation for facial plastic surgical procedures can cause dramatic changes in the appearance of certain parameters. Standardizing patient positioning for preoperative and postoperative photographs is imperative.     

Cathepsin L and Arg/Lys aminopeptidase: a distinct prohormone processing pathway for the biosynthesis of peptide neurotransmitters and hormones

Peptide neurotransmitters and hormones are synthesized as protein precursors that require proteolytic processing to generate smaller, biologically active peptides that are secreted to mediate neurotransmission and hormone actions. Neuropeptides within their precursors are typically flanked by pairs of basic residues, as well as by monobasic residues. In this review, evidence for secretory vesicle cathepsin L and Arg/Lys aminopeptidase as a distinct proteolytic pathway for processing the prohormone proenkephalin is presented. Cleavage of prohormone processing sites by secretory vesicle cathepsin L occurs at the NH2-terminal side of dibasic residues, as well as between the dibasic residues, resulting in peptide intermediates with Arg or Lys extensions at their NH2-termini. A subsequent Arg/Lys aminopeptidase step is then required to remove NH2-terminal basic residues to generate the final enkephalin neuropeptide. The cathepsin L and Arg/Lys aminopeptidase prohormone processing pathway is distinct from the proteolytic pathway mediated by the subtilisin-like prohormone convertases 1/3 and 2 (PC1/3 and PC2) with carboxypeptidase E/H. Differences in specific cleavage sites at paired basic residue sites distinguish these two pathways. These two proteolytic pathways demonstrate the increasing complexity of regulatory mechanisms for the production of peptide neurotransmitters and hormones.     

Multiple functions of tail-anchor domains of mitochondrial outer membrane proteins

Tail-anchored proteins form a distinct class of membrane proteins that have a single membrane anchor sequence at their C-terminus, the tail-anchor. Their N-terminal portion is exposed to the cytosol. We have studied the roles of tail-anchor domains of proteins residing in the mitochondrial outer membrane. Four distinct functions of the tail-anchor domain were identified. First, the domain mediates the targeting to mitochondria in a process that probably requires a net positive charge at the C-terminally flanking segment. Second, tail-anchor domains facilitate the insertion into the mitochondrial outer membrane. Third, the tail-anchor is responsible for the assembly of the respective protein into functional multi-subunit complexes; and fourth, tail-anchor domains can stabilize such complexes.     

betaFSH,betaLH and growth hormone gene expression in blue gourami (Trichogaster trichopterus,Pallas 1770) during spermatogenesis and male sexual behavior

The relationship between gonadal development (histological evidence for spermiogenesis and/or spermatogenesis), sexual behavior (nest-building) and mRNA levels of gonadotropins (betaFSH and betaLH) and growth hormone (GH) in the male pituitary was investigated. Amplification of betaFSH cDNA showed a significantly higher mRNA level in mature males (whether sexually active or not) than in juveniles. However, following PCR amplification of betaLH cDNA, a significantly higher mRNA level was found in the sexually active group compared to the sexually inactive group. These results suggest that FSH may participate in spermatogenesis, whereas LH is more involved in spermiogenesis. The GH mRNA level increased slightly during the maturation process but no significant differences were found between the groups studied.     

Stress‐responsive accumulation of plastid chaperonin 60 during seedling development

Plastid chaperonin 60 (cpn60) is a chloroplast protein, presumed to assist in assembly and folding of plastid proteins. Although molecular chaperones often accumulate significantly in response to stress, this has never been demonstrated for cpn60. In this study, the accumulation of cpn60 in Nicotiana seedlings during their development was followed under different stress conditions. It was found that cpn60 accumulates markedly in developing seedlings in response to tentoxin and several other (but not all) stresses. Cpn60 accumulates only during a narrow period of seedling development. It is proposed that cpn60 accumulation under stress is developmentally regulated.     

The Lipid World

The continuity of abiotically formed bilayer membraneswith similar structures in contemporary cellular life,and the requirement for microenvironments in whichlarge and small molecules could be compartmentalized, support the idea that amphiphilic boundary structurescontributed to the emergence of life. As an extensionof this notion, we propose here a `Lipid World'scenario as an early evolutionary step in theemergence of cellular life on Earth. This conceptcombines the potential chemical activities of lipidsand other amphiphiles, with their capacity to undergospontaneous self-organization into supramolecularstructures such as micelles and bilayers. Inparticular, the documented chemical rate enhancementswithin lipid assemblies suggest that energy-dependentsynthetic reactions could lead to the growth andincreased abundance of certain amphiphilic assemblies.We further propose that selective processes might acton such assemblies, as suggested by our computersimulations of mutual catalysis among amphiphiles. Asdemonstrated also by other researchers, such mutualcatalysis within random molecular assemblies couldhave led to a primordial homeostatic system displayingrudimentary life-like properties. Taken together,these concepts provide a theoretical framework, andsuggest experimental tests for a Lipid World model forthe origin of life.     

Plant-feeding and non-plant feeding phytoseiids: differences in behavior and cheliceral morphology

In previous studies plant feeding behavior of plant- and non-plant feeding phytoseiids was never examined directly. Moreover, in these studies the cheliceral morphology of phytoseiids was not associated with their ability to feed on plants. In the present study, we monitored the plant-feeding behavior of Euseius scutalis and Amblyseius swirskii. Only E. scutalis was observed penetrating the leaf surface with the movable digit and feeding. Second, using a dye and coloring the gut as an indicator for feeding, we found that E. scutalis pierced an artificial membrane and fed whereas A. swirskii did not. Finally, to identify morphological characteristics typical of plant feeders versus non-plant feeders, we used scanning electron microscopy to examine the adaxial (inner) profile of the chelicerae in 13 phytoseiid species. The only parameter that distinguished between plant- and non-plant feeders was the ratio of the dorsal perimeter length of the fixed digit to the ventral perimeter length of the movable digit. Plant-feeders were characterized by ratio values greater than one whereas the values for non plant-feeders were lower than one. We suggest that a shorter and less curved movable digit, expressed by a high ratio, will facilitate the penetration of the leaf surface. Cheliceral traits proposed here as typical of plant feeders, were observed for five genera, indicating that plant-feeding may be more common in the Phytoseiidae than previously reported. We propose that the ability to feed on plants be added as a cross type trait of phytoseiid life-style types.     

Mitochondria can recognize and assemble fragments of a beta-barrel structure

β-barrel proteins are found in the outer membranes of eukaryotic organelles of endosymbiotic origin as well as in the outer membrane of Gram-negative bacteria. Precursors of mitochondrial β-barrel proteins are synthesized in the cytosol and have to be targeted to the organelle. Currently, the signal that assures their specific targeting to mitochondria is poorly defined. To characterize the structural features needed for specific mitochondrial targeting and to test whether a full β-barrel structure is required, we expressed in yeast cells the β-barrel domain of the trimeric autotransporter Yersinia adhesin A (YadA). Trimeric autotransporters are found only in prokaryotes, where they are anchored to the outer membrane by a single 12-stranded β-barrel structure to which each monomer is contributing four β-strands. Importantly, we found that YadA is solely localized to the mitochondrial outer membrane, where it exists in a native trimeric conformation. These findings demonstrate that, rather than a linear sequence or a complete β-barrel structure, four β-strands are sufficient for the mitochondria to recognize and assemble a β-barrel protein. Remarkably, the evolutionary origin of mitochondria from bacteria enables them to import and assemble even proteins belonging to a class that is absent in eukaryotes.     

Structure-templated predictions of novel protein interactions from sequence information

The multitude of functions performed in the cell are largely controlled by a set of carefully orchestrated protein interactions often facilitated by specific binding of conserved domains in the interacting proteins. Interacting domains commonly exhibit distinct binding specificity to short and conserved recognition peptides called binding profiles. Although many conserved domains are known in nature, only a few have well-characterized binding profiles. Here, we describe a novel predictive method known as domain–motif interactions from structural topology (D-MIST) for elucidating the binding profiles of interacting domains. A set of domains and their corresponding binding profiles were derived from extant protein structures and protein interaction data and then used to predict novel protein interactions in yeast. A number of the predicted interactions were verified experimentally, including new interactions of the mitotic exit network, RNA polymerases, nucleotide metabolism enzymes, and the chaperone complex. These results demonstrate that new protein interactions can be predicted exclusively from sequence information.