Search Results (5,602)

Orphan enzymes are recognized and classified enzymatic activities that lack associated amino acid sequences. Since the term was coined in the mid-2000s, the proportion of orphan enzymes has substantially decreased; however, it is estimated that at least ≈900 enzymatic activities remain devoid of molecular identity to date. The putative mammalian metabolic pathway for L-fucose degradation represents a system that long consisted exclusively of orphan enzymes, with only a few recently “deorphaned” and biochemically characterized. L-Fucose is a unique monosaccharide frequently found in various glycolipids and glycoproteins synthesized by mammalian cells, such as the ABO blood group antigens in humans. While the importance of the biosynthetic pathways for its active form (GDP-L-fucose) is well established in diverse biological processes, the enzymology and physiological role of L-fucose catabolism remain largely enigmatic. In this review, we summarize the current knowledge regarding the enzymological and physiological aspects of L-fucose catabolism in mammals. Full article

Avian influenza viruses (AIVs) are widely distributed and have a wide range of hosts. Recently, the number of cases of infection associated with the circulation of highly pathogenic avian influenza H5N1 2.3.4.4b has raised concerns about its high transmission capacity in birds and mammals. This study analyzed swabs from bird and mammal species from the coast of Paraná and the northwest region of São Paulo, Brazil, for the presence of AIV in animals that did not present clinical or histopathological lesions of infection that indicated the need for molecular characterization during monitoring. Of the 661 animals analyzed, three tested positive, two of which were birds (Sula leucogaster and Thalasseus acuflavidus) while one was a mammal (Otaria flavescens) (0.45%, CI 95%: 0.16–1.33). A complete genome sequence of H5N1 AIV was obtained from a brown booby (Sula leucogaster) from the Paraná coast (GISAID accession number: EPI_ISL_1897537). Our study reinforces the importance of continuous genomic surveillance, especially in AIV hosts that do not show signs of infection, to enhance the One-Health assessment approach. Full article

The transforming growth factor-beta (TGF-β) superfamily regulates diverse biological processes, including proliferation, differentiation, apoptosis, tissue remodeling, and reproductive signaling across metazoans. Here, we performed a genome-wide characterization of the TGF-β gene family in donkey (Equus asinus, ASM1607732v2) using comparative genomics and bioinformatics analyses, with horse (Equus caballus, EquCab3.0) as a reference to investigate evolutionary conservation and functional divergence. Genome assemblies and proteomes were retrieved from NCBI, and TGF-β genes were identified using BLASTp and HMMER searches (Pfam PF00019), followed by phylogenetic, conserved motif, synteny, Ka/Ks, mutation prediction, subcellular localization, and tissue-specific expression analyses. We identified 40 TGF-β genes in donkeys, exceeding the numbers reported in several mammals, suggesting possible lineage-specific expansion or differential gene retention within Equidae. Phylogenetic and motif analyses demonstrated strong evolutionary conservation across the two principal clades (TGF-β-like and BMP-like). Four segmental duplications were identified, with Ka/Ks ratios ranging from 0.28 to 0.43, indicating strong purifying selection on duplicated genes. Synteny analysis revealed extensive collinearity with the horse genome, supporting conserved equid genomic architecture. Comparative sequence analysis identified 160 amino acid variants, including 11 predicted deleterious mutations in key genes (GDF6, GDF9, GDF10, BMP15, and RGMA), suggesting potential functional divergence associated with reproductive and developmental pathways. Importantly, transcriptomic validation using publicly available donkey RNA-seq tissue expression data (NCBI BioProject: PRJNA1017964) revealed distinct tissue-specific expression patterns, with reproductive tissues (ovary and uterus) displaying enriched expression of TGF-β/BMP signaling components, particularly TGFBR1, TGFBR2, TGFB1, BMP2, BMP4, and BMP7, while canonical fecundity genes (GDF9 and BMP15) exhibited ovary-associated expression. This receptor-dominant signaling profile may have a coordinated TGF-β regulatory network underlying folliculogenesis, reproductive tissue remodeling, and fertility-related processes in donkeys. Subcellular localization predictions showed that most proteins (22/40) were extracellularly localized, consistent with conserved signaling functions. Together, this study provides the first integrated genomic and tissue-expression atlas of the donkey TGF-β superfamily, offering new insights into equid-specific evolutionary conservation, reproductive signaling, and functional divergence. Full article

Heat shock proteins of the 70 kDa family (HSP70s) are essential molecular chaperones that preserve proteostasis by assisting protein folding, transport, and degradation. Although the core HSP70 architecture is deeply conserved, the degree and functional significance of sequence divergence across vertebrates remain incompletely understood. Here, an integrative comparative analysis of HSP70 proteins from ten representative vertebrate species spanning mammals, birds, amphibians, and teleost fish was performed. Multiple sequence alignment, phylogenetic reconstruction, motif discovery, entropy-based conservation profiling, hydrophobicity analysis, and structural mapping reveal a strikingly conserved ATPase domain alongside a more variable substrate-binding domain and C-terminal region. Multiple Expectation Maximization for Motif Elicitation (MEME) motif analysis identifies both universally conserved motifs and lineage-specific elements, highlighting functional constraint as well as adaptive diversification. Structural projection onto the human HSP70 crystal structure (PDB 5AQV) demonstrates that conserved hydrophobic residues cluster in the protein core, whereas variable residues are predominantly surface-exposed. Together, these findings illuminate how evolutionary pressures shape both the conserved chaperone machinery and flexible regulatory regions of HSP70, and they establish a scalable analytical framework for comparative protein evolution studies. Full article

Sulfur-containing amino acids (SCAA) and their metabolites constitute an integrated metabolic network essential for central nervous system (CNS) function. In mammals, sulfur metabolism links one-carbon metabolism, the methionine cycle and the transsulfuration pathway, thereby connecting nutrient availability with redox regulation, methylation reactions, neurotransmitter synthesis and cellular adaptation to stress. Among these metabolites, methionine, cysteine, glutathione, taurine, homocysteine and hydrogen sulfide play key roles in neuronal physiology, mitochondrial homeostasis, synaptic plasticity and antioxidant defense. Alterations in SCAA metabolism have been increasingly associated with neurological and neurodevelopment disorders, which share common features such as oxidative stress, mitochondrial dysfunction, altered glutamatergic signaling, impaired methylation capacity and neuroinflammation. These pathological mechanisms are also observed following exposure to toxic metals, suggesting the existence of convergent pathways between environmental neurotoxicity and neurological diseases. Several studies showed that chronic exposure to arsenic, mercury, cadmium, lead, and other toxic metals disrupts sulfur amino acid homeostasis by affecting methionine remethylation, transsulfuration activity, glutathione synthesis and reactive sulfur species production. Due to sulfur-containing metabolites possessing antioxidant and metal-binding properties, these pathways are also involved in adaptive detoxification response. However, sustained disruption of sulfur metabolism may compromise neuronal resilience and increase vulnerability to neurological dysfunction. This narrative review integrates current evidence on the physiological roles of SCAA in the CNS, and examines how toxic metals disrupt sulfur metabolic pathways. By combining findings from experimental studies, human data and exploratory transcriptomic analyses, we propose that disruption of SCAA homeostasis represents a mechanistic link between environmental metal exposure and increased vulnerability to neurological disease. Full article

The role of birds of the Strigiformes order in the transmission of globally distributed Sarcocystis parasites remains insufficiently studied. In the present work we aimed to evaluate the diversity of Sarcocystis species in the intestines of 22 naturally infected Tawny Owls (Strix aluco) sampled in Lithuania. The Sarcocystis infection was established using combined light microscopy and DNA sequence analysis. Samples were analyzed using Sarcocystis-genus and species-specific primers in nested PCR followed by Sanger sequencing. Sporocysts of Sarcocystis spp. were detected in 45.5% of samples, while 77.3% of samples were positive by molecular methods. Comparison of 28S rRNA and ITS1 sequences obtained and phylogenetic analyses indicated the presence of eight Sarcocystis taxa: S. halieti, S. kutkienae, S. turdusi, and Sarcocystis sp. ex Corvus corax, associated with birds, and S. funereus, S. glareoli, Sarcocystis sp. LT24Sa1, and Sarcocystis sp. LT24Sa11, associated with small mammals. Our results supplement previous findings that some Sarcocystis species can be transmitted by birds of three orders: Accipitriformes, Falconiformes, and Strigiformes. Overall, the low burden of sporocysts and predominance of single-species infections (63.6%) suggest that Tawny Owls transmit a limited number of Sarcocystis species associated with small mammals and birds. Full article

Background/Objectives: Healthy animals can harbor complex and diverse bacterial communities, including pathogenic taxa capable of causing disease and mortality, and individuals that are kept in zoos may act as asymptomatic carriers of a broad range of pathogens. Therefore, this study aimed to investigate the rectal bacterial microbiota of multiple animal classes (reptiles, birds, and mammals), maintained in enclosures, identify known or emerging bacterial pathogens, and characterize the antibiotic resistance profiles of the isolated strains. Methods: A total of 40 samples were collected by rectal swabbing for bacteriological analysis from 31 different animal species living in enclosures in four Algerian zoos. The isolated and identified bacterial strains were tested against certain antibiotics used in human and veterinary medicine. Statistical analyses were performed to assess differences in bacterial isolation among animal classes, sex, age categories, and zoological facilities, as well as the degree of similarity between isolated strains based on their antibiotic resistance profiles. Results: A total of 94 bacterial isolates were recovered from 40 fecal samples. Overall, the bacterial isolates belonged to seven families, 13 genera, and 16 taxa. The families identified were Enterobacteriaceae (50/94; 53.19%), Staphylococcaceae (28/94; 29.78%), Pseudomonadaceae (6/94; 6.38%), Brucellaceae (2/94; 2.12%), Morganellaceae (4/94; 4.25%), Yersiniaceae (3/94; 3.19%), and Erwiniaceae (1/94; 1.06%). Reptiles accounted for the highest number of isolates (37/94; 39.36%), followed by 31/94 isolates (32.97%) for birds and 26/94 isolates (27.65%) for mammals. The highest resistance rates were observed for ampicillin (AMP; 95.73%), followed by amoxicillin/clavulanic acid (AMC; 75.54%) and cephalothin (CEP; 44.90%). Lower resistance rates were detected for trimethoprim–sulfamethoxazole (SXT; 18.87%), cefotaxime (CTX; 17.41%), ceftazidime (CX; 13.67%), ciprofloxacin (CIP; 6.38%), and gentamicin (GEN; 1.05%). Conclusion: This study shows the first report that vertebrates in Algerian zoos can harbor a diverse range of cultivable bacteria, often with polymicrobial carriage. Antimicrobial resistance patterns were generally consistent with commonly used veterinary drugs. Overall, these findings contribute to a better understanding of the composition of rectal bacterial carriage in zoos. Full article

Genetic recombination occurs in many organisms, from simple RNA viruses to mammals and plants with DNA genomes. In sexual reproduction, two parental genomes come together and undergo recombination, producing an offspring genome with a combination of information from the two parental genomes. Genome recombination that occurs during sexual reproduction can involve any one of several mechanisms, including copy-choice recombination as well as breakage and exchange. Across widely different organisms, recombination is generally promoted by factors that damage the genetic material. In organisms such as bacteriophage and Paramecium, it was experimentally demonstrated that recombinational repair during sexual reproduction can overcome otherwise deleterious or lethal damage. For many decades, it has been recognized that there are higher biological costs of sexual reproduction than for asexual reproduction. Theories assuming that genetic variation, due to recombination, is the main adaptive benefit of sexual reproduction have been widely accepted. Such a benefit was considered to compensate for the high cost of sexual reproduction. However, it has been difficult to find a strong, consistent benefit of variation. The repair of lethal damage, involving recombinational interactions of two different genomes, now appears to be the major selective factor underlying sexual reproduction in organisms both simple and complex. Full article

This review describes a novel method for increasing the effectiveness of inactivated enveloped whole-virus vaccines by targeting them for extensive uptake by antigen-presenting cells (APCs). Several inactivated whole-virus vaccines with dense glycan shields display suboptimal effectiveness because the multiple carbohydrate chains (glycans) on the virus mask immunogenic peptides and surround the virus with a negative electrostatic charge that decreases uptake by APCs. It is postulated that engineering such vaccinating viruses to present the carbohydrate antigen “α-gal epitope” on the glycan shields will immunocomplex them with the anti-Gal antibody; thus, it will target them for robust uptake by APCs. Anti-Gal is an abundant natural antibody in humans, constituting ~1% of human circulating immunoglobulins. The ligand of anti-Gal is the α-gal epitope, which is naturally synthesized in non-primate mammals and New World monkeys by the glycosylation enzyme α1,3galactosyltransferase. This enzyme is encoded by the GGTA1-gene. Viral vaccines presenting multiple α-gal epitopes on their glycan shield bind anti-Gal and activate the complement system to produce complement chemotactic cleavage peptides C5a and C3a that induce extensive recruitment of APCs to vaccine injection sites. The virion-bound anti-Gal further targets the viral vaccine for robust uptake by APCs, following binding of its Fc “tail” to Fcγ-receptors on APCs. The efficacy of this method was studied in anti-Gal-producing mice with α-gal presenting inactivated influenza virus vaccine and with gp120 of HIV presenting this epitope. These studies indicated that virus vaccines engineered to present α-gal epitopes increase anti-virus antibody production and virus-specific T-cell activation by 15- to 100-fold in comparison to the same vaccines lacking α-gal epitopes. It is suggested that α-gal presenting inactivated SARS-CoV-2 virus vaccines can induce a similar protective long-term immune memory against S- M-, E-, and N-viral proteins. Furthermore, immune-escaping variants of the mutated S-protein may be destroyed by antibodies to M and E proteins, and cells infected with such variants may be killed by cytotoxic T cells specific to peptides of the N-protein. Such an anti-M-, E-, and N-protein immune protection may prevent expansion of these variants and thus may avoid the need for immunization with COVID-19 vaccines every 6 months or following the appearance of new variants. A similar potent immunization may be achieved with an inactivated Ebolavirus vaccine engineered to present α-gal epitopes on the glycan shield. The resulting immune response to the various Ebolavirus proteins also may contribute to cross-reactive protection against other Ebolavirus species containing proteins with evolutionarily conserved structures. An effective method for the preparation of a whole-virus vaccine presenting α-gal epitopes is by arming it with the GGTA1-gene inserted into the viral genome. Such virions will present multiple α-gal epitopes on their glycan shield, which will amplify their immunogenicity instead of reducing it in the wild-type virus. Full article

Yaks (Bos grunniens) are large mammals endemic to the Qinghai–Tibet Plateau. Efficient lung development is crucial for their adaptation to high-altitude hypoxia. As progenitor cells of the alveoli, type II alveolar epithelial (AT2) cells warrant further investigation into their physiological functions; however, relevant studies remain limited. In this study, primary AT2 cells were isolated from the lungs of yaks. Concurrently, lung tissues were collected from yaks at distinct developmental stages to investigate the role of the EGF/EGFR axis in regulating AT2 cell proliferation and apoptosis, as well as its essential contribution to yak lung development. Here, we demonstrate that the EGF/EGFR axis plays a beneficial role in yak alveolar development. Exogenous EGF supplementation or EGFR activation upregulated the downstream factors AKT and STAT3, enhanced AT2 cell proliferation, and reduced apoptosis. In contrast, EGFR inhibition promoted AT2 cell apoptosis and suppressed proliferation. Cell cycle analysis revealed that both exogenous EGF and EGFR activation increased the proportion of AT2 cells in the S and G2 phases, whereas EGFR inhibition caused cell cycle arrest at the G0/G1 phase. Moreover, the expression of cell cycle regulators cyclin D1, CDK4, and CDK6 was upregulated, while p16 and p21 expression was downregulated. Further comparative analyses indicated that the EGF/EGFR axis positively contributes to alveolar development in juvenile yaks. Collectively, these findings confirm that in plateau environments, activation of the EGF/EGFR axis promotes AT2 cell proliferation and inhibits apoptosis, thereby facilitating alveolar development in juvenile yaks. A key limitation is the lack of parallel comparisons with low-altitude cattle and other plateau-endemic species (e.g., Tibetan sheep), which precludes definitive assessment of the specificity of the EGFR/EGF axis in yak AT2 cell proliferation and lung development. Full article

The voltage-dependent anion channel (VDAC) is the primary conduit for ion and metabolite transport across the mitochondrial outer membrane. Positioned at the interface between the cytosol and the mitochondrial compartment, VDAC is uniquely accessible to proteins on both sides of the membrane, making it an interaction hub whose biophysical properties and signaling functions are shaped by protein complexation in addition to its intrinsic pore specialization. Mammals express three isoforms—VDAC1, VDAC2, and VDAC3—sharing a conserved β-barrel scaffold with about 70% identity. However, minor differences in the sequence lead to drastic changes in VDAC isoform affinity with other proteins. Here, we review the molecular mechanisms and physiological consequences of VDAC complexation with a set of well-characterized partners: hexokinase, dimeric tubulin, α-synuclein, mitochondria-associated membrane proteins, B-cell lymphoma 2 (BCL-2) family proteins, and the translocase of the outer membrane (TOM) protein import complex. For each complex, we evaluate the available structural, biophysical, and genetic evidence for isoform specificity, highlight where mechanistic understanding is most advanced, and identify open questions. A consistent principle emerges across all complexes: functionally nonredundant isoform contributions are primarily governed by differential partner affinity and complexation, rather than by differences in pore architecture alone. This framework has direct implications for mitochondria-associated pathologies, including cancer, cardiovascular disease, and neurodegeneration, as well as for the rational design of VDAC-targeting therapeutics. Full article

Background: During life, all organisms experience multiple stressful events capable of disrupting their somatic integrity. As mammals, humans respond to environmental, sociocultural, and cognitive stressors via allostasis, a systemic neurophysiological response that supports physiological homeostasis. Unfortunately, allostatic mechanisms are incapable of countering all stressors, and systemic physiological damage accumulates with age; thereby contributing to physiological dysregulation and an increasing allostatic load (AL). Previously, we reported that a ten-factor allostatic load index (ALI) varied significantly by age, gender, and rural–urban residence in a sample of Polish citizens ages 55+ years but a five-biomarker frailty index did not. Here we determine whether an estimated ALI covaries with self-reported food intakes across age, residential setting, and gender. Methods: Two hundred and ten residents of Greater Poland ages 55–91 years, residing in either the Nekla commune (N = 103) or the capital of Greater Poland, Poznan (N = 107), participated in research designed to estimate a study-specific 10-biomarker ALI and its possible associations with their self-reported dietary choices, age, gender, and residential location. Of these, 206 completed study protocols including a food frequency questionnaire, verifying their age, self-reporting their gender, and allowing research personnel to obtain data for assessing 10 physiological biomarkers of allostatic load for inclusion in a study-specific ALI. Statistical significance for nominal measures was estimated using chi-square analyses; those for continuous measures, t-tests. Results: In the full sample, self-reported higher red meat and snack intakes were significantly associated with higher ALI at younger ages (55–69 years). No food item was significantly associated with estimated ALI at older ages (70+ years). Further, low self-reported intakes of fish and seafood consumption were significantly associated with a higher ALI in Poznan, but not Nekla residents. Within the full sample, average ALI was almost identical between younger and older women. Conclusions: In this cross-sectional sample of older Nekla and Poznan residents allostatic load not only varied by age, sex, and residential location, but also with self-reported consumption of red meat, snacks, fish and seafood. Observed differences in biomarkers of AL between younger and older residents of Poland across this sample suggest possible higher incidences of chronic disease occur among women residing in Nekla than those in Poznan. Similarly, the significant associations of red meat and snack consumption with ALI at younger ages in both settings may portend increasing vascular disease and related complications among those ages 55–69 years in this sample as they age. As does the higher estimated ALI among Poznan residents reporting low fish and seafood consumption. Full article

“Immature” or “late-maturing” neurons exist in layer II of the cerebral cortex (cortical immature neurons; cINs) and within the amygdaloid complex (subcortical immature neurons; scINs). These cells remain in a prolonged state of arrested development yet retain the ability to resume maturation and to functionally integrate into neural circuits. Both cINs and scINs are abundant in large-brained mammals with respect to small-brained, lissencephalic rodents. In previous reports, using a comparable method for quantification in diverse mammals, including mice, chimpanzees, and other species, we showed positive correlation of immature neuron cell density with brain size and gyrencephaly. Here, we quantified the cINs and scINs in the cerebral cortex and amygdala of young adult rhesus macaques to determine how they compare to phylogenetic variation. Our results further demonstrate the existence of covariance between cIN density and both increasing brain size and neocortical expansion, as well as the specialized increase of scINs in the amygdala of primates. These findings support the emerging view that immature neurons may represent a reservoir of undifferentiated (stem cell-independent) neuronal cells for the widely expanded cortices and amygdala of mammals endowed with high-order cognitive functions and complex sociality. The detailed mapping of cortical and subcortical immature neurons in a primate often used in translational research sets the foundation for deeper, functional studies aimed at understanding human brain plasticity. Full article

The subgenus Megatrypanum Hoare, 1964, with the type species Trypanosoma theileri Laveran, 1902, comprises stercorarian trypanosomes of mammals. A substantial portion of this subgenus consists of T. theileri-like trypanosomes parasitizing cervids and bovids worldwide. Similar to most other members of the genus Trypanosoma that lack obvious economic importance, the biology of T. theileri-like trypanosomes remains poorly understood. In particular, fundamental aspects such as their host specificity, host–parasite interactions, and the morphology of developmental stages have been studied only to a limited extent. In this work, we provide a detailed description of the development and cellular organization of T. theileri-like trypanosomes in the horsefly Hybomitra montana using transmission electron microscopy (TEM). We show for the first time that T. theileri-like trypanosomes possess a well-developed cytostome–cytopharyngeal complex, morphologically similar to those in other stercorarian trypanosomes. This complex is present in the studied trypanosomes at the epimastigote stage and degrades during metacyclogenesis. In the host ileum, epimastigotes and trypomastigotes at different stages of metacyclogenesis are embedded in a fibrillar matrix that isolates them from the gut lumen. This promotes their accumulation in the vector, thereby increasing the efficiency of future infection of the vertebrate host, which occurs via contamination of the oral mucosa. Full article

Pubertal initiation critically determines reproductive performance in female pigs. Histone H3 lysine 27 trimethylation (H3K27me3) has been implicated in ovarian development. However, its genome-wide regulatory landscape during the pubertal transition remains unexplored. Here, we obtained transcriptomes of GCs treated with the pharmacological H3K27me3 agonist GSK-J4 or H3K27me3 inhibitor EPZ005687. We found that H3K27me3 substantially remodels the transcriptomic landscape of porcine GCs, with differentially expressed genes significantly enriched in pathways governing cell proliferation and apoptosis. Mechanistically, H3K27me3 suppressed GC proliferation by downregulating the expression of PCNA and promoting apoptosis through upregulation of CASP3, thereby delaying pubertal initiation. Furthermore, genome-wide ChIP-seq analysis on porcine ovaries from pre-pubertal and in-pubertal gilts revealed higher H3K27me3 enrichment around transcription start sites in the In-puberty stage than in the Pre-puberty stage. Genes with promoters exhibiting reduced H3K27me3 occupancy during the pubertal transition were enriched in pathways related to sex differentiation and serine-type endopeptidase inhibitor activity. Notably, secretory leukocyte peptidase inhibitor (SLPI) was identified by ChIP-qPCR as a direct target repressed by H3K27me3. Functional validation demonstrated that SLPI promoted GC proliferation and inhibited GC apoptosis in vitro. Intraperitoneal injection of LV-Slpi or sh-Slpi into C57BL/6J mice showed that Slpi accelerated pubertal initiation of mice in vivo. Collectively, our findings confirmed that developmental stage-specific loss of H3K27me3 at the SLPI promoter derepressed SLPI transcription, which in turn promoted porcine GC proliferation, suppressed apoptosis, and facilitated pubertal initiation in mice. These results provided valuable insights into the epigenetic regulation of pubertal initiation in mammals. Full article