Reproductive responses of male Brandt's voles (Lasiopodomys brandtii) to 6-methoxybenzoxazolinone (6-MBOA) under short photoperiod

RNA-seq transcriptome analysis provides new insights into the negative effects of tannic acid on the intestinal function of Brandt's voles (Lasiopodomys brandtii)

Tannic acid (TA), a significant plant secondary metabolite, is contained in the daily food of Brandt's voles. Its adverse effect on gut function has been shown in earlier research, but the underlying molecular mechanisms remain uncertain. In this study, male Brandt's vole (13 weeks old) were divided into two groups and given 0 (control) or 1,200 (TA-treated) mg•kg-1 TA for 18 days. Then RNA sequencing was used to conduct a thorough transcriptome analysis on the duodenum, jejunum, and ileum of Brandt's voles. Results showed that TA significantly increased serum total cholesterol concentration (P < 0.05) and decreased the nutrient digestibility (P < 0.05) of Brandt's voles. Furthermore, there were 174 differentially expressed genes (DEGs) in the duodenum, 96 DEGs in the jejunum, and 88 DEGs in the ileum between the control and TA-treated groups. Enrichment analysis revealed that many genes associated with bile secretion, fat digestion and absorption, innate immune response, and tight junction such as ABCG2, ABCG8, PEAK1, and IFR2, etc. were altered after TA treatment, which were verified by quantitative real-time PCR. These findings suggested that TA can change the expression of intestinal genes, thereby, altering nutrition metabolism and immunological function, eventually hindering the growth of Brandt's voles. The results of this study provide a theoretical basis for explaining how TA affects the gut function of Brandt's voles at the molecular level.

Effect of 6-Methoxybenzoxazolinone on the Cecal Microbiota of Adult Male Brandt's Vole

The anti-microbial effects of plant secondary metabolite (PSM) 6-methoxybenzoxazolinone (6-MBOA) have been overlooked. This study investigated the effect of 6-MBOA on the cecal microbiota of adult male Brandt’s voles (Lasiopodomys brandtii), to evaluate its effect on the physiology of mammalian herbivores. The growth of voles was inhibited by 6-MBOA. A low dose of 6-MBOA enhanced the observed species, as well as the Chao1 and abundance-based coverage estimator (ACE) indices and introduced changes in the structure of cecal microbiota. The abundance of the phylum Tenericutes, classes Mollicutes and Negativicutes, order Selenomonadales, families Ruminococcaceae and Veillonellaceae, genera Quinella, Caproiciproducens, Anaerofilum, Harryflintia, and unidentified Spirochaetaceae in the cecal microbiota was enhanced upon administration of a low dose of 6-MBOA, which also inhibited glucose metabolism and protein digestion and absorption in the cecal microbiota. 6-MBOA treatment also stimulated butyrate production and dose-dependently enhanced the metabolism of xenobiotics in the cecal microbiome. Our findings indicate that 6-MBOA can affect Brandt’s voles by inducing changes in the abundance of cecal bacteria, thereby, altering the contents of short-chain fatty acids (SCFAs) and pathway intermediates, ultimately inhibiting the growth of voles. Our research suggests that 6-MBOA could potentially act as a digestion-inhibiting PSM in the interaction between mammalian herbivores and plants.

Timing outweighs magnitude of rainfall in shaping population dynamics of a small mammal species in steppe grassland

Disentangling the effects of rainfall timing and magnitude on animal and plant populations is essential to reveal the biological consequence of diverse climate change scenarios around the world. We conducted a 10-y, large-scale, manipulative experiment to examine the bottom-up effects of changes in rainfall regime on the population dynamics of Brandt’s voles in the steppe grassland of Inner Mongolia, China. We found that a moderate rainfall increase during the early growing season could produce marked increases in vole population size by increasing the biomass of preferred plant species, whereas large increases in rainfall produced no additional increase in vole population growth. Our study highlights the importance of rainfall magnitude and timing on the nonlinear population dynamics of herbivores.

Climate change–induced shifts in species phenology differ widely across trophic levels, which may lead to consumer–resource mismatches with cascading population and ecosystem consequences. Here, we examined the effects of different rainfall patterns (i.e., timing and amount) on the phenological asynchrony of population of a generalist herbivore and their food sources in semiarid steppe grassland in Inner Mongolia. We conducted a 10-y (2010 to 2019) rainfall manipulation experiment in 12 0.48-ha field enclosures and found that moderate rainfall increases during the early rather than late growing season advanced the timing of peak reproduction and drove marked increases in population size through increasing the biomass of preferred plant species. By contrast, greatly increased rainfall produced no further increases in vole population growth due to the potential negative effect of the flooding of burrows. The increases in vole population size were more coupled with increased reproduction of overwintered voles and increased body mass of young-of-year than with better survival. Our results provide experimental evidence for the fitness consequences of phenological mismatches at the population level and highlight the importance of rainfall timing on the population dynamics of small herbivores in the steppe grassland environment.

Effect of gallic acid on the reproduction of adolescent male Brandt’s voles (Lasiopodomys brandtii)

Gallic acid (GA), a phenol that is present in various plants, potentially contains antioxidant properties. This study aimed to investigate the effects of GA on the reproduction of adolescent male Brandt’s voles (Lasiopodomys brandtii (Radde, 1861)). Antioxidant levels and apoptosis in the testis, as well as reproductive physiology, were evaluated in adolescent males treated with GA. The results showed that a low dose of GA enhanced relative epididymis mass and the sperm density in the epididymis, increased the mRNA levels of steroidogenic acute regulatory protein in the testis, and reduced the percentages of abnormal and dead sperm. In addition, a low dose of GA significantly increased the levels of superoxide dismutase, catalase, and glutathione peroxidase, and decreased the level of malondialdehyde in the testis, as well as the mRNA and protein levels of the apoptosis-related gene, caspase-3. However, a high dose of GA sharply reduced the mean diameter of the seminiferous tubules compared with a low dose. Collectively, these findings demonstrate that GA treatment during puberty affects the reproductive responses of male Brandt’s voles in a dose-dependent manner by regulating antioxidant levels and apoptosis.

The KiSS-1/GPR54 system: Essential roles in physiological homeostasis and cancer biology

KiSS-1, first identified as an anti-metastasis gene in melanoma, encodes C-terminally amidated peptide products, including kisspeptin-145, kisspeptin-54, kisspeptin-14, kisspeptin-13 and kisspeptin-10. These products are endogenous ligands coupled to G protein-coupled receptor 54 (GPR54)/hOT7T175/AXOR12. To date, the regulatory activities of the KiSS-1/GPR54 system, such as puberty initiation, antitumor metastasis, fertility in adulthood, hypothalamic-pituitary-gonadal axis (HPG axis) feedback, and trophoblast invasion, have been investigated intensively. Accumulating evidence has demonstrated that KiSS-1 played a key role in reproduction and served as a promising biomarker relative to the diagnosis, identification of therapeutic targets and prognosis in various carcinomas, while few studies have systematically summarized its subjective factors and concluded the functions of KiSS-1/GPR54 signaling in physiology homeostasis and cancer biology. In this review, we retrospectively summarized the regulators of the KiSS-1/GPR54 system in different animal models and reviewed its functions according to physiological homeostasis regulations and above all, cancer biology, which provided us with a profound understanding of applying the KiSS-1/GPR54 system into medical applications.

Effect of Group Density on the Physiology and Aggressive Behavior of Male Brandt's Voles (Lasiopodomys brandtii)

Xin Dai, Ling-Yu Zhou, Jie-Xia Cao, Yan-Qi Zhang, Feng-Ping Yang, Ai-Qin Wang, Wan-Hong Wei, and Sheng-Mei Yang (2018) Population density is well known to influence animal physiology and behavior. How population density affects the aggressive behavior of the Brandt's vole (Lasiopodomys brandtii) is, however, little known. The aim of this study was to investigate the effect of group density on physiologic responses and aggressive behavior of male Brandt's voles and their potential underlying neuro-mechanism. The results show that increasing group density led to elevated serum corticosterone levels and increased spleen weight; it also induced more male-male aggressive behavior. By contrast, it had a negative effect on body growth and the weight of testis and epididymis. Aging also increased male-male aggressive behavior. Higher density reduced mRNA levels of tryptophan hydroxylase 2 (TPH2), 5-hydroxytryptamine receptor 1A (5HT1A), and 5-hydroxytryptamine receptor 1B (5HT1B) in the amygdala and the dorsal raphe nucleus (DRN). Our results demonstrate that higher population density can intensify stress reactions and male-male aggressive behavior in Brandt's voles at the price of inhibiting body growth and reproduction. Serotonergic systems in the amygdala and the DRN may take part in the control of aggressive behavior among male voles. Our results provide novel insights into the neuro-mechanism underlying the influence of population density on aggressive behavior in Brandt's vole, and imply that aggressive behavior may play an important role in the population fluctuation of the animal.

Effect of photoperiod and 6-methoxybenzoxazolinone (6-MBOA) on the reproduction of male Brandt's voles (Lasiopodomys brandtii)

Plant secondary metabolite 6-methoxybenzoxazolinone (6-MBOA) has been suggested to stimulate animal reproduction. 6-MBOA is detected in Leymus chinensis, a main diet of Brandt's vole (Lasiopodomys brandtii). We have previously reported a stimulatory effect of 6-MBOA on reproduction of male Brandt's voles under a short-day photoperiod. The goal of this study was to investigate the effect of 6-MBOA on reproductive physiology of male Brandt's voles under a long-day photoperiod and examine if 6-MBOA under this photoperiodic regime altered the reproductive status of male Brandt's voles differently than the short-day photoperiod. Under the long-day photoperiod, a high dose of 6-MBOA decreased KiSS-1 mRNA in the arcuate nucleus (ARC), and we also saw a decrease in circulating levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone (T). Steroidogenic acute regulatory protein (StAR) and cytochrome P450_11a1 (CYP11a1) in the testes, and relative testis weight also decreased with 6-MBOA administration. Compared to the short-day photoperiod, animals under the long-day photoperiod exhibited increased body weight as well as all other reproductive parameters. Our results showed that 6-MBOA inhibited the reproduction of male Brandt's vole under a long-day photoperiod, a stark contrast from its stimulatory effects under a short-day photoperiod. The paradoxical effects of 6-MBOA suggest it may act as a partial agonist of melatonin. These results provide insight into the complex interactions between environmental factors such as photoperiod and diet in the control of Brandt's vole reproduction.