Arvicanthis

A study on the composition and seasonality of rodent diet was carried out during 2020-2022 years in Chimit Kola to determine the type, relative proportion and seasonality of food items consumed. A total of 166 stomach contents that belong to six rodent species ( Mastomys awashensis , Acomys louisae , Arvicanthis raffertyi , Lophuromys simensis , Gerbilliscus sp. and Lemniscomys macculus ) were investigated. Parametric and non-parametric analyses of variance were used to test the difference. Leaves and stems, seeds, invertebrates, fruits and unidentified food matters were the food items identified in the stomach contents of rodents...

In mammalian research, it has been debated what can initiate an evolutionary trade-off between different senses, and the phenomenon of sensory trade-off in rodents, the most abundant mammalian clade, is not evident. The Nile rat (Arvicanthis niloticus), a murid rodent, recently adapted to a diurnal niche through an evolutionary acquisition of daylight vision with enhanced visual acuity. As such, this model provides an opportunity for a cross-species investigation where comparative morphological and multi-omic analyses of the Nile rat are made with its closely related nocturnal species, e...

The African grass or Nile rat (NR) (Arvicanthis niloticus) is a herbivorous diurnal rodent which is used as a biological model for research on type 2 diabetes mellitus (T2DM) and the circadian rhythm. Similar to humans, male NRs develop T2DM with high-carbohydrate diets. The NR thus provides a unique opportunity to identify the nutritional and underlying genetic factors that characterise human T2DM, as well as the effects of potential anti-diabetic phytochemicals such as Water-Soluble Palm Fruit Extract. Whole genome sequencing (WGS) could help identify possible genetic causes why NRs spontaneously develop T2DM in captivity...

Seasonal affective disorder (SAD) is a recurrent depression triggered by exposure to short photoperiods, with a subset of patients reporting hypersomnia, increased appetite, and carbohydrate craving. Dysfunction of the microbiota - gut - brain axis is frequently associated with depressive disorders, but its role in SAD is unknown. Nile grass rats ( Arvicanthis niloticus ) are potentially useful for exploring the pathophysiology of SAD, as they are diurnal and have been found to exhibit anhedonia and affective-like behavior in response to short photoperiods...

Type 2 diabetes is a challenge in modern healthcare, and animal models are necessary to identify underlying mechanisms. The Nile rat (Arvicanthis niloticus) develops diet-induced diabetes rapidly on a conventional rodent chow diet without genetic or chemical manipulation. Unlike common laboratory models, the outbred Nile rat model is diurnal and has a wide range of overt diabetes onset and diabetes progression patterns in both sexes, better mimicking the heterogeneous diabetic phenotype in humans. While fasted blood glucose has historically been used to monitor diabetic progression, postprandial blood glucose is more sensitive to the initial stages of diabetes...

Urbanization processes are taking place at a very high rate, especially in Africa. At the same time, a number of small mammal species, be they native or invasive, take advantage of human-induced habitat modifications. They represent commensal communities of organisms that cause a number of inconveniences to humans, including potential reservoirs of zoonotic diseases. We studied via live trapping and habitat characterization such commensal small mammal communities in small villages to large cities of Senegal, to try to understand how the species share this particular space...

Diurnal and nocturnal mammals have evolved distinct pathways to optimize survival for their chronotype-specific lifestyles. Conventional rodent models, being nocturnal, may not sufficiently recapitulate the biology of diurnal humans in health and disease. Although diurnal rodents are potentially advantageous for translational research, until recently, they have not been genetically tractable. Here, we address this major limitation by demonstrating the first successful CRISPR genome editing of the Nile grass rat ( Arvicanthis niloticus ), a valuable diurnal rodent...

BACKGROUND: Bright light therapy (BLT) is widely used for treating Seasonal Affective Disorder (SAD). However, the neural mechanisms underlying the therapeutic effects of BLT remain largely unexplored. The present study used a diurnal rodent (Nile grass rats; Arvicanthis niloticus ) to test the hypothesis that the therapeutic effects of BLT could be, in part, due to reduced neuroinflammation and/or enhanced neuroplasticity. Our previous research has demonstrated that compared to grass rats housed in a summer-like daytime bright light condition (1000 lux), those housed in a winter-like daytime dim light condition (50 lux) showed increased depression- and anxiety-like behaviours, as well as impaired sociosexual behaviours and spatial memory, similar to what is observed in patients suffering from SAD...

Beyond visual perception, light has non-image-forming effects mediated by melanopsin-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs). The present study first used multielectrode array recordings to show that in a diurnal rodent, Nile grass rats ( Arvicanthis niloticus ), ipRGCs generate rod/cone-driven and melanopsin-based photoresponses that stably encode irradiance. Subsequently, two ipRGC-mediated non-image-forming effects, namely entrainment of daily rhythms and light-induced arousal, were examined...

BACKGROUND: Bright light therapy (BLT) is the first-line treatment for seasonal affective disorder. However, the neural mechanisms underlying BLT are unclear. To begin filling this gap, the present study examined the impact of BLT on sleep/wakefulness, daily rhythms, and the wakefulness-promoting orexin/hypocretin system in a diurnal rodent, Nile grass rats (Arvicanthis niloticus). METHODS: Male and female grass rats were housed under a 12:12 h light/dark cycle with dim light (50 lx) during the day...

The noradrenergic Locus Cœruleus is one of the major arousal structures involved in inducing wakefulness. While brain noradrenaline (NA) amounts display 24-h variations, the origin of NA rhythm is currently unknown. In this study, we tested the hypothesis that NA rhythm could result from its rhythmic synthesis. Therefore, we investigated the 24-h expression profile of NA rate-limiting enzyme, tyrosine hydroxylase (th), in the Locus Cœruleus (LC) of the nocturnal rat and the diurnal rodent Arvicanthis, under 12 h:12 h light/dark (LD) and constant darkness (DD) conditions...

BACKGROUND: Assemblages of mummified and preserved animals in necropoleis of Ptolemaic Period Egypt (ca. 332-30 BC) document some aspects of the ceremonial and religious practices of the ancient Egyptians, but study of these animal remains can also provide insight into the local environments in which the animals and humans lived. RESULTS: Excavations of the Sacred Falcon Necropolis at Quesna in the Nile Delta have yielded many thousands of animal remains, mostly of raptors, but also of a lesser number of small, wild mammals...

RNA sequencing (RNA-seq) has been a widely used high-throughput method to characterize transcriptomic dynamics spatiotemporally. However, RNA-seq data analysis pipelines typically depend on either a sequenced genome and/or corresponding reference transcripts. This limitation is a challenge for species lacking sequenced genomes and corresponding reference transcripts. The Nile rat (Arvicanthis niloticus) has two key features - it is daytime active, and it is prone to diet-induced diabetes, which makes it more similar to humans than regular laboratory rodents...

In mammals, daily physiological activities are regulated by a central circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). Recently, an increasing number of studies have used diurnal grass rats to analyze neuronal mechanisms regulating diurnal behavior. However, spontaneous action potential firing rhythms in SCN neurons have not been demonstrated clearly in diurnal grass rats. Therefore, the present study examined extracellular single-unit recordings from SCN neurons in acute hypothalamic slices of Arvicanthis niloticus (Nile grass rats)...

BACKGROUND: The Nile rat (Avicanthis niloticus) is an important animal model because of its robust diurnal rhythm, a cone-rich retina, and a propensity to develop diet-induced diabetes without chemical or genetic modifications. A closer similarity to humans in these aspects, compared to the widely used Mus musculus and Rattus norvegicus models, holds the promise of better translation of research findings to the clinic. RESULTS: We report a 2.5 Gb, chromosome-level reference genome assembly with fully resolved parental haplotypes, generated with the Vertebrate Genomes Project (VGP)...

OBJECTIVE: Whether dietary carbohydrate (CHO) or fat is more involved in type 2 diabetes (T2DM) induction uncomplicated by dietary fiber was addressed in a spontaneous diabetic model, the diurnal Nile rat that mimics the human condition. METHODS: A total of 138 male Nile rats were fed plant-based and animal-based saturated fat where 10% energy as CHO and fat were exchanged across 5 diets keeping protein constant, from 70:10:20 to 20:60:20 as CHO:fat:protein %energy...

Seasonal changes in peripheral inflammation are well documented in both humans and animal models, but seasonal changes in neuroinflammation, especially the impact of seasonal lighting environment on neuroinflammation remain unclear. To address this question, the present study examined the effects of environmental lighting conditions on neuroinflammation in a diurnal rodent model, Nile grass rats (Arvicanthis niloticus). Male and female grass rats were housed in either bright (brLD) or dim (dimLD) light during the day to simulate a summer or winter light condition, respectively...

PURPOSE: In many retinal pathological conditions, rod and cone degeneration differs. For example, the early-onset maculopathy Stargardts disease type 1 (STGD1) is typified by loss of cones while rods are often less affected. We wanted to examine whether there exist intrinsic membrane differences between rods and cones that might explain such features. METHODS: Abca4 mRNA and protein levels were quantified in rod- and cone-enriched samples from wild-type and Nrl-/- mice retinas; rod- and cone-enriched outer segments (ROS and COS respectively) were prepared from pig retinas, and total lipids were analyzed by flame ionization, chromatography, and tandem mass spectrometry...

Ectoparasite load in small mammals can be influenced by both environmental conditions and host species characteristics. However, the nature of these influences is poorly understood in many ecosystems. We used zero-inflated negative binomial (ZINB) regression models with a log link function to assess variation in ectoparasite load among 19 small mammal host species across different land uses (protection in a park, pastoralism and agriculture), habitat types, seasons, age classes, sexes and breeding statuses...

Evolution of vertebrate endemics in oceanic islands follows a predictable pattern, known as the island rule, according to which gigantism arises in originally small-sized species and dwarfism in large ones. Species of extinct insular giant rodents are known from all over the world. In the Canary Islands, two examples of giant rats, † Canariomys bravoi and † Canariomys tamarani , endemic to Tenerife and Gran Canaria, respectively, disappeared soon after human settlement. The highly derived morphological features of these insular endemic rodents hamper the reconstruction of their evolutionary histories...