Single-cell RNA sequencing technology (scRNA-seq) has been steadily developing since its inception in 2009. Unlike bulk RNA-seq, scRNA-seq identifies the heterogeneity of tissue cells and reveals gene expression changes in individual cells at the microscopic level. Here, we review the development of scRNA-seq, which has gone through iterations of reverse transcription, in vitro transcription, smart-seq, drop-seq, 10 × Genomics, and spatial single-cell transcriptome technologies. The technology of 10 × Genomics has been widely applied in medicine and biology, producing rich research results. Furthermore, this review presents a summary of the analytical process for single-cell transcriptome data and its integration with other omics analyses, including genomes, epigenomes, proteomes, and metabolomics. The single-cell transcriptome has a wide range of applications in biology and medicine. This review analyzes the applications of scRNA-seq in cancer, stem cell research, developmental biology, microbiology, and other fields. In essence, scRNA-seq provides a means of elucidating gene expression patterns in single cells, thereby offering a valuable tool for scientific research. Nevertheless, the current single-cell transcriptome technology is still imperfect, and this review identifies its shortcomings and anticipates future developments. The objective of this review is to facilitate a deeper comprehension of scRNA-seq technology and its applications in biological and medical research, as well as to identify avenues for its future development in alignment with practical needs.

Camel milk is known for its exceptional medical uses. It has been used since ancient times to treat infant diarrhea, hepatitis, insulin-dependent diabetes (IDDM), lactose intolerance, alcohol-induced liver damage, allergies, and autism. It has the power to treat several diseases, with cancer being the most significant. This study investigated the evolutionary relationship, physiochemical characteristics, and comparative genomic analysis of the casein gene family (CSN1S1, CSN2, CSN1S2, and CSN3) in Camelus ferus. Molecular phylogenetics showing the camelid species clustered casein nucleotide sequences into four groups: CSN1S1, CSN2, CSN1S2, and CSN3. The casein proteins from camels were evaluated and found to be unstable, thermostable, and hydrophilic. CSN1S2, CSN2, and CSN3 were acidic, but CSN1S1 was basic. CSN1S1 showed positive selection for one amino acid (Q), CSN1S2 and CSN2 for three (T, K, Q), and CSN3 showed no positive selection. We also compared high-milk-output species such as cattle (Bos Tarus) and low-milk-yield species such as sheep (Ovies Aries) with camels (Camel ferus) and discovered that YY1 sites are more frequent in sheep than in camels and very low in cattle. We concluded that the ratio of YY1 sites in these species may affect milk production.

Dairy products contain complex types and contents of proteins, lipids, and lactose. The Maillard reaction (MR) occurs between proteins and reducing sugars during the processing and storage of dairy products. Maillard reaction products (MRPs) have garnered attention for their potential antioxidant activity. MRPs include melanoidins, reductones, and volatile heterocyclic compounds, which affect flavor and color. Relevant literature was identified through a structured search of PubMed and Web of Science; studies were included if they investigated MRPs in dairy products and reported antioxidant-related outcomes. This review offers a comprehensive overview of the MR in dairy products, systematically investigating the influence of protein, reducing sugars, and their ratios, as well as reaction conditions (process technology, temperature, time, pH, and water activity) on the formation and antioxidant activity of MRPs. The review also covers current applications and the future potential of MRPs as natural antioxidants in dairy products. Although MRPs effectively delay lipid oxidation and enhance stability in dairy products, research on their molecular structure and antioxidant mechanisms remains insufficient. Future research should focus on understanding the multifactorial synergistic effects within the complex dairy matrix, elucidating the molecular structure and extraction of antioxidant substances, and developing regulatory techniques to balance the antioxidant properties of MRPs with the safety concerns of potential harmful byproducts.

Double-Layer Steamed Milk Custard (DLSMC) is a famous traditional Chinese dessert. This study aimed to analyze the flavor and the changes in metabolites during different stages of DLSMC preparation, including raw buffalo milk, thermo-processing, first and second-layer milk skin formation. Electronic nose and electronic tongue were employed to preliminarily assess the overall flavor characteristics between these stages. The results indicated that DLSMC demonstrated increased sweetness, saltiness, and umami compared to raw buffalo milk, along with heightened levels of nitrogen oxides, methane, alcohols, aldehydes, ketones, and sulfur-containing compounds. Thus, the thermo-processing and second-layer milk skin formation were pinpointed as critical for flavor alterations. Additionally, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) detected a total of 46 volatile organic compounds (VOCs), with 8 compounds identified as key flavor components. Untargeted metabolomics revealed 98 differential metabolites, including amino acids, lipids, and nucleotides, that were significantly linked to changes in key flavor compounds. Indeed, the fluctuations in the levels of amino acids, lipids, and nucleotides play a crucial role in influencing flavor changes during the production of DLSMC made from buffalo milk.

Leeches are significant medicinal invertebrates, particularly well-known for their strong bioactive substances and therapeutic uses in analgesia, anticoagulation, and anti-inflammatory conditions. Despite this, insufficient information is available about the molecular processes driving species-specific functional diversity. We conducted a comparative transcriptomic study of three medically valuable leech species, Hirudinaria manillensis, Hirudo nipponia, and Whitmania pigra, and explored the interspecies differences in gene expression and regulatory networks. In total, 18,107 mRNAs and 183 long non-coding RNAs (lncRNAs) were identified from 27 cDNA libraries, and pairwise comparison differential gene expression analysis retrieved 1681, 2156, and 468 DEGs in HM vs HN, HM vs WP, and HN vs WP, respectively, with 81 common genes among all species. These DEGs are mainly enriched in muscle growth, metabolic regulation, and cytoskeletal structure. Muscle-related genes (TPM, TNNT, and TNNI) exhibited higher expressions in H. nipponia, suggesting greater contractile adaptability, whereas H. manillensis displayed high expression of anticoagulant (HIRM2, ANTA, FLNA, PROS), analgesic (AGRIN, MMEL1, NEP), and anti-inflammatory (MMP17, MMP25, TLR4, CYTB) genes, highlighting its robust pharmacological potential. In contrast, W. pigra had comparatively lower expression of these functional genes. Besides, co-expression evaluation presented DElncRNAs, including MSTRG.1617, MSTRG.484, and MSTRG.1673 were shown to be crucial cis-regulators of muscle and bioactive genes (TPM, TNNT, PROS, and MMP25), demonstrating intricate lncRNA–mRNA connections influencing physiological specificity. Together, we provided the first transcriptome comparison of medicinal leech species, signifying their molecular basis of muscle function and therapeutic efficiency, establishing a fundamental resource for future multi-omics integration, functional gene validation, and targeted molecular breeding to advance leech-derived medicinal applications.