A comparative analysis of fruit fly and human glutamate dehydrogenases in Drosophila melanogaster sperm development

Neanderthal and Denisovan Glutamate Dehydrogenase 2 Evolution and Clinical Significance

Mammalian glutamate dehydrogenase (GDH) is an indispensable metabolic enzyme. GDH duplication has led to the presence of two paralogs, GDH1 and GDH2, in apes. Multiple GDH pseudogenes are also present in the human genome. The novel GDH2, supposed to be a target of positive selection, differs from GDH1 in regulation and is believed to be tightly linked to brain development. Although the differences of modern human GDH2 from GDH2 of other apes have been studied, the evolution of ancient human GDH2 remains a blank space. The goal of this work was to elucidate GDH2 evolution in the genus Homo using the accumulated data on the ancient genomes with high coverage-three Neanderthal and one Denisovan genome. Such analysis clarifies the difference between GDH2 of the last common ancestor of humans and chimpanzees and all Homo to be in M468L substitution, localized in the regulatory "antenna" region of the protein. A few novel missense mutations have been found in Denisovan and Altai Neanderthal GDH2, namely R76H, present in both genomes, and Denisovan-specific T154P, I358L, and S498A substitutions. Another mutation, R352K, has likely occurred independently in modern humans and later Neanderthals. The potential impact of these mutations was estimated using GDH2 structural data and evidence from contemporary medical data. All substitutions are supposed to be benign, with only the S498A GDH2 substitution connected to Parkinson's disease with late onset. Additionally, the ancient genomes were revealed to have all GDH pseudogenes present in modern humans, including the RNA-coding ones. The GLUD1P3 RNA expression was found to correlate negatively with GDH1 in human tissues. A possible regulatory role has been proposed, and the GLUD1P3 RNA sequence identity in all the studied human genomes suggests its conservation in the genus Homo.

A metabolomic study uncovering key amino acids and amines in Duroc boar semen as biomarkers of sexual maturity

Metabolomic analysis of boar semen associated with sexual maturation is essential for improving fertility management and breeding, with amino acids and amines playing key roles in the reproductive process. This study aimed to explore changes in amino acids and amines in boar spermatozoa and seminal plasma during puberty to sexual maturity and identify potential biomarkers of sexual maturity. Semen was collected from the same 15 Duroc boars over time at approximately 7 months (Age 1), 8.5 months (Age 2), and 10 months (Age 3). Liquid chromatography-mass spectrometry was used to analyse amino acids and amines in spermatozoa and seminal plasma separately. Multivariate analysis (PLS-DA) revealed pronounced age-dependent changes in amino acids and amines in spermatozoa between Age 1 and Age 3, and more subtle shifts in seminal plasma. Univariate analysis (Repeated measure ANOVA/Friedman) revealed that glutamate and taurine had significant pairwise differences in seminal plasma (P < 0.05). In sperm, 15 amino acids (glutamate, alanine, aspartate, choline, taurine, histidine, methionine, tryptophan, leucine, cystine, tyrosine, arginine, lysine, valine and glycine) exhibited significant pairwise differences (P < 0.05). VIP scoring (>1.5) prioritised glutamate, alanine, aspartate, and choline as key contributors to the variations and pathway analysis implicated alanine, aspartate and glutamate metabolism, and histidine metabolism linked to sexual maturity. Our study highlights metabolic changes during sexual maturation, identifying potential biomarkers for assessing reproductive maturity. These findings are initial steps toward optimising younger boars' usage in breeding, enhancing genetic gain, and reducing costs associated with their non-productive days at AI centres.

Evolutionary Changes in Primate Glutamate Dehydrogenases 1 and 2 Influence the Protein Regulation by Ligands, Targeting and Posttranslational Modifications

There are two paralogs of glutamate dehydrogenase (GDH) in humans encoded by the GLUD1 and GLUD2 genes as a result of a recent retroposition during the evolution of primates. The two human GDHs possess significantly different regulation by allosteric ligands, which is not fully characterized at the structural level. Recent advances in identification of the GDH ligand binding sites provide a deeper perspective on the significance of the accumulated substitutions within the two GDH paralogs. In this review, we describe the evolution of GLUD1 and GLUD2 after the duplication event in primates using the accumulated sequencing and structural data. A new gibbon GLUD2 sequence questions the indispensability of ancestral R496S and G509A mutations for GLUD2 irresponsiveness to GTP, providing an alternative with potentially similar regulatory features. The data of both GLUD1 and GLUD2 evolution not only confirm substitutions enhancing GLUD2 mitochondrial targeting, but also reveal a conserved mutation in ape GLUD1 mitochondrial targeting sequence that likely reduces its transport to mitochondria. Moreover, the information of GDH interactors, posttranslational modification and subcellular localization are provided for better understanding of the GDH mutations. Medically significant point mutations causing deregulation of GDH are considered from the structural and regulatory point of view.

Mitochondrial Differentiation during Spermatogenesis: Lessons from Drosophila melanogaster

Numerous diseases can arise as a consequence of mitochondrial malfunction. Hence, there is a significant focus on studying the role of mitochondria in cancer, ageing, neurodegenerative diseases, and the field of developmental biology. Mitochondria could exist as discrete organelles in the cell; however, they have the ability to fuse, resulting in the formation of interconnected reticular structures. The dynamic changes between these forms correlate with mitochondrial function and mitochondrial health, and consequently, there is a significant scientific interest in uncovering the specific molecular constituents that govern these transitions. Moreover, the specialized mitochondria display a wide array of variable morphologies in their cristae formations. These inner mitochondrial structures are closely associated with the specific functions performed by the mitochondria. In multiple cases, the presence of mitochondrial dysfunction has been linked to male sterility, as it has been observed to cause a range of abnormal spermatogenesis and sperm phenotypes in different species. This review aims to elucidate the dynamic alterations and functions of mitochondria in germ cell development during the spermatogenesis of Drosophila melanogaster.