Positive selection and sequence rearrangements generate extensive polymorphism in the gamete recognition protein bindin

Bindin is a gamete recognition protein of sea urchins that mediates species-specific attachment of sperm to an egg-surface receptor during fertilization. Sequences of bindin from closely related urchins show fixed species-specific differences. Within species, highly polymorphic bindin alleles result from point substitution, insertion/deletion, and recombination. Since speciation, positive selection favoring allelic variants has generated diversity in bindin polypeptides. Intraspecific bindin variation can be tolerated by the egg receptor, which suggests functional parallels between this system and other flexible recognition systems, including immune recognition. These results show that polymorphism in mate recognition loci required for rapid evolution of sexual isolation can arise within natural populations.      

New flourinated chitin derivatives: synthesis, characterization and cytotoxicity assessment

New fluorinated chitin derivatives have been synthesized and characterized. Fluorination of chitin was achieved by facile homogenous reaction of chitin solution with diethyl amino sulfur trifluoride (C₄H₁₀NSF₃). The degree of substitution of the C6-hydroxyl functionality of N-acetyl-glucosamine repeat unit ranged from 50 to 98%, achieved by varying the reaction time from 1 to 144 h at room temperature. The use of pentafluoropropionic anhydride, trifluoromethylbenzoyl chloride and pentafluorobenzoyl chloride gave fluoro-chitin derivatives with 40, 10 and 5% substitution, respectively. Solid-state nuclear magnetic resonance and Fourier-transform infrared spectroscopy, powder X-ray diffraction, and elemental analysis support the identity of all fluorinated chitin derivatives. The fluorinated chitin derivatives were subjected to MTT assay using human (ATCC CCL-186) and mouse (ATCC CCL-1) fibroblast cell lines. Fluorinated chitin derivatives prepared from C₄H₁₀NSF₃ at 1, 6, 12, 72 and 96 h showed good cell viability of 80–100% for human fibroblast and 60–70% for mouse fibroblast. The % cell viability for the other fluorinated chitin derivatives were above 60% for both cell lines.     

Upper limbs dysmetria caused by cervical spinal cord injury: a case report

Background  

Upper limbs dysmetria caused by spinal cord injury is very rare. We will discuss the associated mechanism in our articles.     

Towards an integrated understanding of the structural characteristics of protein residue networks

A protein residue network or PRN is a network induced by spatial contacts between amino acid residues of a protein. Studies of the structure of PRNs have revealed a list of network characteristics common to a diverse class of proteins. Explanations for the observed network characteristics for protein folding have been suggested but not tested in an integrated way. In this article, in silico experiments are performed to understand how structural characteristics of PRNs influence protein folding as modeled by a search problem. We find that the blend of structural characteristics PRNs possess help to place them in a sweet spot within the space of all network configurations tested. PRNs are plausible 3D structures and yield competitive search performances. Hence, it appears that PRNs are in a form suited to the function they evolved into. However, this conclusion is partially contingent upon the fitness function preferentially satisfying short-range links but also allowing short- and long-range interactions to cooperate towards the satisfaction of all links. We close with a discussion on the rather intricate interplay among the three main structural characteristics of PRNs, i.e., clustering, average path length, and assortativity, and their impact on search performance and 3D structure plausibility.     

A likelihood method for the detection of selection and recombination using nucleotide sequences

Different regions along nucleotide sequences are often subject to different evolutionary forces. Recombination will result in regions having different evolutionary histories, while selection can cause regions to evolve at different rates. This paper presents a statistical method based on likelihood for detecting such processes by identifying the regions which do not fit with a single phylogenetic topology and nucleotide substitution process along the entire sequence. Subsequent reanalysis of these anomalous regions may then be possible. The method is tested using simulations, and its application is demonstrated using the primate psi eta-globin pseudogene, the V3 region of the envelope gene of HIV-1, and argF sequences from Neisseria bacteria. Reanalysis of anomalous regions is shown to reveal possible immune selection in HIV-1 and recombination in Neisseria. A computer program which implements the method is available.      

Ethnobiology of snappers (Lutjanidae): target species and suggestions for management

In this study, we sought to investigate the biology (diet and reproduction) and ethnobiology (fishers knowledge and fishing spots used to catch snappers) of five species of snappers (Lutjanidae), including Lutjanus analis, Lutjanus synagris, Lutjanus vivanus, Ocyurus chrysurus, and Romboplites saliens at five sites along the northeast (Riacho Doce, Maceió in Alagoas State, and Porto do Sauípe, Entre Rios at Bahia State) and the southeast (SE) Brazilian coast (Paraty and Rio de Janeiro cities at Rio de Janeiro State, and Bertioga, at São Paulo State.). We collected 288 snappers and interviewed 86 fishermen. The stomach contents of each fish were examined and macroscopic gonad analysis was performed. Snappers are very important for the fisheries of NE Brazil, and our results indicated that some populations, such as mutton snapper (L. analis) and lane snapper (L. synagris), are being caught when they are too young, at early juvenile stages. Local knowledge has been shown to be a powerful tool for determining appropriate policies regarding management of target species, and artisanal fishermen can be included in management processes. Other suggestions for managing the fisheries are discussed, including proposals that could provide motivation for artisanal fishermen to participate in programs to conserve resources, such as co-management approaches that utilize local knowledge, the establishment of fishing seasons, and compensation of fishermen, through 'payment for environmental services'. These suggestions may enhance the participation of local artisanal fishermen in moving to a more realistic and less top-down management approach of the fish population.     

Why Do People Feed Free-roaming Cats? The Role of Anticipated Regret in an Extended Theory of Planned Behavior in Malaysia

Free-roaming cats are common in residential and public areas in Malaysia and approach people for food. However, the psychological determinants of public feeding are unknown. This study investigated public perceptions of feeding free-roaming cats, based on an extended theory of planned behavior (TPB). It consisted of qualitative belief-elicitation interviews with 25 participants, followed by a quantitative survey of 167 participants, representative of the country’s population. The majority (87.2%) of the sample had fed free-roaming cats. The mean intention score (4.88 out of 7) indicated the public was likely, and would make an effort, to feed free-roaming cats in the future. The public’s benevolence toward animals largely explained the findings, based on generally positive attitudes and perceptions of moderate social credence and capability and confidence, underpinned by affective and cognitive beliefs. An important finding was the role of anticipated regret in predicting and explaining intentions, which contributed variance over and above that explained by the TPB constructs. The extended framework is explained by the influence of anticipated regret on the perceived evaluation of potential TPB outcomes, which in turn leads to the behavior becoming less volitional. Therefore, future TPB studies of people’s interactions with animals, such as free-roaming cats, should take account of affective and emotional antecedents of behavior, such as anticipated regret, to improve explanatory power. The study also has implications for managing public feeding of free-roaming cats, such as drawing on and strengthening the Malaysian public’s positive attitudes and emotional concern to redirect current feeding practices toward more constructive animal welfare initiatives. Such humane approaches align with the public’s sensitivity toward animal welfare and the historical development of cat population control from lethal methods to humane non-lethal methods to ensure adequate care.     

Targeting myomiRs by tocotrienol-rich fraction to promote myoblast differentiation

Background

Several muscle-specific microRNAs (myomiRs) are differentially expressed during cellular senescence. However, the role of dietary compounds on myomiRs remains elusive. This study aimed to elucidate the modulatory role of tocotrienol-rich fraction (TRF) on myomiRs and myogenic genes during differentiation of human myoblasts. Young and senescent human skeletal muscle myoblasts (HSMM) were treated with 50 μg/mL TRF for 24 h before and after inducing differentiation.

Results

The fusion index and myotube surface area were higher (p?<?0.05) on days 3 and 5 than that on day 1 of differentiation. Ageing reduced the differentiation rate, as observed by a decrease in both fusion index and myotube surface area in senescent cells (p?<?0.05). Treatment with TRF significantly increased differentiation at days 1, 3 and 5 of young and senescent myoblasts. In senescent myoblasts, TRF increased the expression of miR-206 and miR-486 and decreased PTEN and PAX7 expression. However, the expression of IGF1R was upregulated during early differentiation and decreased at late differentiation when treated with TRF. In young myoblasts, TRF promoted differentiation by modulating the expression of miR-206, which resulted in the reduction of PAX7 expression and upregulation of IGF1R.

Conclusion

TRF can potentially promote myoblast differentiation by modulating the expression of myomiRs, which regulate the expression of myogenic genes.

     

Electrolytic extraction drives volatile fatty acid chain elongation through lactic acid and replaces chemical pH control in thin stillage fermentation

Background

Volatile fatty acids (VFA) are building blocks for the chemical industry. Sustainable, biological production is constrained by production and recovery costs, including the need for intensive pH correction. Membrane electrolysis has been developed as an in situ extraction technology tailored to the direct recovery of VFA from fermentation while stabilizing acidogenesis without caustic addition. A current applied across an anion exchange membrane reduces the fermentation broth (catholyte, water reduction: H₂O + e^? → ½ H₂ + OH^?) and drives carboxylate ions into a clean, concentrated VFA stream (anolyte, water oxidation: H₂O → 2e^? + 2 H⁺ + O₂).

Results

In this study, we fermented thin stillage to generate a mixed VFA extract without chemical pH control. Membrane electrolysis (0.1 A, 3.22 ± 0.60 V) extracted 28 ± 6 % of carboxylates generated per day (on a carbon basis) and completely replaced caustic control of pH, with no impact on the total carboxylate production amount or rate. Hydrogen generated from the applied current shifted the fermentation outcome from predominantly C2 and C3 VFA (64 ± 3 % of the total VFA present in the control) to majority of C4 to C6 (70 ± 12 % in the experiment), with identical proportions in the VFA acid extract. A strain related to Megasphaera elsdenii (maximum abundance of 57 %), a bacteria capable of producing mid-chain VFA at a high rate, was enriched by the applied current, alongside a stable community of Lactobacillus spp. (10 %), enabling chain elongation of VFA through lactic acid. A conversion of 30 ± 5 % VFA produced per sCOD fed (60 ± 10 % of the reactive fraction) was achieved, with a 50 ± 6 % reduction in suspended solids likely by electro-coagulation.

Conclusions

VFA can be extracted directly from a fermentation broth by membrane electrolysis. The electrolytic water reduction products are utilized in the fermentation: OH^? is used for pH control without added chemicals, and H₂ is metabolized by species such as Megasphaera elsdenii to produce greater value, more reduced VFA. Electro-fermentation displays promise for generating added value chemical co-products from biorefinery sidestreams and wastes.