The somatic chromosomes of the Mongolian gerbil /Meriones unguiculatus/

Somatic chromosomes study of Mongolian gerbil

Gerbil: A Fast and Memory-Efficient kk-mer Counter with GPU-Support

A basic task in bioinformatics is the counting of $k$-mers in genome strings. The $k$-mer counting problem is to build a histogram of all substrings of length $k$ in a given genome sequence. We present the open source $k$-mer counting software Gerbil that has been designed for the efficient counting of $k$-mers for $k\geq32$. Given the technology trend towards long reads of next-generation sequencers, support for large $k$ becomes increasingly important. While existing $k$-mer counting tools suffer from excessive memory resource consumption or degrading performance for large $k$, Gerbil is able to efficiently support large $k$ without much loss of performance. Our software implements a two-disk approach. In the first step, DNA reads are loaded from disk and distributed to temporary files that are stored at a working disk. In a second step, the temporary files are read again, split into $k$-mers and counted via a hash table approach. In addition, Gerbil can optionally use GPUs to accelerate the counting step. For large $k$, we outperform state-of-the-art open source $k$-mer counting tools for large genome data sets.Comment: A short version of this paper will appear in the proceedings of WABI 201

Population Coding of Interaural Time Differences in Gerbils and Barn Owls

Interaural time differences (ITDs) are the primary cue for the localization of low-frequency sound sources in the azimuthal plane. For decades, it was assumed that the coding of ITDs in the mammalian brain was similar to that in the avian brain, where information is sparsely distributed across individual neurons, but recent studies have suggested otherwise. In this study, we characterized the representation of ITDs in adult male and female gerbils. First, we performed behavioral experiments to determine the acuity with which gerbils can use ITDs to localize sounds. Next, we used different decoders to infer ITDs from the activity of a population of neurons in central nucleus of the inferior colliculus. These results show that ITDs are not represented in a distributed manner, but rather in the summed activity of the entire population. To contrast these results with those from a population where the representation of ITDs is known to be sparsely distributed, we performed the same analysis on activity from the external nucleus of the inferior colliculus of adult male and female barn owls. Together, our results support the idea that, unlike the avian brain, the mammalian brain represents ITDs in the overall activity of a homogenous population of neurons within each hemisphere

Time course of oxidative damage in different brain regions following transient cerebral ischemia in gerbils

The time course of oxidative damage in different brain regions was investigated in the gerbil model of transient cerebral ischemia. Animals were subjected to both common carotid arteries occlusion for 5 min. After the end of ischemia and at different reperfusion times (2, 6, 12, 24, 48, 72, 96 h and 7 days), markers of lipid peroxidation, reduced and oxidized glutathione levels, glutathione peroxidase, glutathione reductase, manganese-dependent superoxide dismutase (MnSOD) and copper/zinc containing SOD (Cu/ZnSOD) activities were measured in hippocampus, cortex and striatum. Oxidative damage in hippocampus was maximal at late stages after ischemia (48-96 h) coincident with a significant impairment in glutathione homeostasis. MnSOD increased in hippocampus at 24, 48 and 72 h after ischemia, coincident with the marked reduction in the activity of glutathione-related enzymes. The late disturbance in oxidant-antioxidant balance corresponds with the time course of delayed neuronal loss in the hippocampal CA1 sector. Cerebral cortex showed early changes in oxidative damage with no significant impairment in antioxidant capacity. Striatal lipid peroxidation significantly increased as early as 2 h after ischemia and persisted until 48 h with respect to the sham-operated group. These results contribute significant information on the timing and factors that influence free radical formation following ischemic brain injury, an essential step in determining effective antioxidant intervention

Population studies on gerbils of the western desert of Egypt, with special reference to Gerbillus andersoni DE Winton

Population studies on the gerbil, Gerbillus andersoni, were carried out in Omayed in the Western Desert of Egypt during the period from July 1976 through August 1978 inclusive. Studies included determination of the sex ratio in the different age and weight groups, as well as seasonal changes in this ratio. The mean weight and age at the onset of maturity and the reproductive activity of both sexes were determined. The study also included seasonal changes in mean body weights of both sexes, those of the testes in relation to body weights, as well as changes in the length of the testis and of the cauda epididymis. Changes in the age structure of the population were also studied

Anatomical identification of primary auditory cortex in the developing gerbil

Cortical development is an active field of study. The gerbil provides an excellent model for research because at the moment of birth its brain is rather immature, anatomically and functionally. Furthermore, the gerbil auditory cortex is particularly amenable to investigation in that the gerbil\u27s onset of hearing occurs approximately after 14 days of postnatal life. Despite these advantages of the gerbil for auditory cortex development not much is known about the anatomy of the postnatal gerbil auditory cortex. For example, where is the gerbil auditory cortex? Prior to the onset of hearing, sounds cannot be used to localize auditory cortex. Therefore, the localization of the auditory cortex with anatomical landmarks alone during development is necessary. Anatomical and physiological approaches to localize the auditory cortex are published in the literature, but evaluated only in adult gerbils, and many of them are based on the fresh brain slice preparation and not applicable in vivo. The present study compares the anatomical references of the adult gerbil published in the literature with the anatomical references in the developing gerbil. Using specific blood vessel positions as landmarks, the position of the primary auditory cortex was estimated on fixed brains and in vivo. The lipophilic tracer Neurovue was used to confirm whether the position resulting from the anatomical analysis was consistent with the position of the auditory cortex. The results showed that anatomical references present already in the developing gerbil are consistently related to the position of the auditory cortex and they can be reliable used as landmarks to detect the actual position of the auditory cortex

Mapping Children's Discussions of Evidence in Science to Assess Collaboration and Argumentation

The research reported in this paper concerns the development of children's skills of interpreting and evaluating evidence in science. Previous studies have shown that school teaching often places limited emphasis on the development of these skills, which are necessary for children to engage in scientific debate and decision-making. The research, undertaken in the UK, involved four collaborative decision-making activities to stimulate group discussion, each was carried out with five groups of four children (10-11 years old). The research shows how the children evaluated evidence for possible choices and judged whether their evidence was sufficient to support a particular conclusion or the rejection of alternative conclusions. A mapping technique was developed to analyse the discussions and identify different "levels" of argumentation. The authors conclude that suitable collaborative activities that focus on the discussion of evidence can be developed to exercise children's ability to argue effectively in making decisions