Cellular localization of a metabotropic glutamate receptor in rat brain.

In rat brain, the cellular localization of a phosphoinositide-linked metabotropic glutamate receptor (mGluR1 alpha) was demonstrated using antibodies that recognize the C-terminus of the receptor. mGluR1 alpha, a 142 kd protein, is enriched within the olfactory bulb, stratum oriens of CA1 and polymorph layer of dentate gyrus in hippocampus, globus pallidus, thalamus, substantia nigra, superior colliculus, and cerebellum. Lower levels of mGluR1 alpha are present within neocortex, striatum, amygdala, hypothalamus, and medulla. Dendrites, spines, and neuronal cell bodies contain mGluR1 alpha. mGluR1 alpha is not detectable in presynaptic terminals. mGluR1 alpha and ionotropic alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor subunits show differential distributions, but in Purkinje cells, mGluR1 alpha and specific AMPA receptor subunits colocalize. The postsynaptic distribution of mGluR1 alpha is consistent with postulated physiological roles of this subtype of glutamate receptor.     

Human GluR6 Kainate Receptor (GRIK2): Molecular Cloning, Expression, Polymorphism, and Chromosomal Assignment

Glutamate receptors mediate the majority of excitatory neurotransmission in the brain, and molecular cloning studies have revealed several distinct families. Because neuropathological states and possibly human disorders may involve kainate-preferring glutamate receptors, we have isolated a cDNA clone for the human GluR6 kainate-preferring receptor. This clone shows a very high sequence similarity with that of the rat, except for a part of the 3′ untranslated region in which there is a TAA triplet repeat. When the protein was overexpressed in human embryonic kidney 293 cells, it had a molecular weight, an antibody recognition, and a glutamate ligand-binding profile similar to those of the rat GluR6 receptor. Northern analysis showed expression in both human cerebral and cerebellar cortices. By PCR analysis of rodent-human monochromosomal cell lines, the human GluR6 could be assigned to chromosome 6. The length of the TAA triplet repeat was polymorphic in the normal population, with at least four alleles and an observed heterozygosity of about 45%. These studies should provide the basis for expression or linkage studies of the GluR6 kainate receptor in human disease or neuropathologic states.     

Geographic differences in Blainville's beaked whale (Mesoplodon densirostris) echolocation clicks

Aim

Understanding cetacean species' distributions and population structure over space and time is necessary for effective conservation and management. Geographic differences in acoustic signals may provide a line of evidence for population-level discrimination in some cetacean species. We use acoustic recordings collected over broad spatial and temporal scales to investigate whether global variability in echolocation click peak frequency could elucidate population structure in Blainville's beaked whale (Mesoplodon densirostris), a cryptic species well-studied acoustically.

Location

North Pacific, Western North Atlantic and Gulf of Mexico.

Time period

2004–2021.

Major taxa studied

Blainville's beaked whale.

Methods

Passive acoustic data were collected at 76 sites and 150 cumulative years of data were analysed to extract beaked whale echolocation clicks. Using an automated detector and subsequent weighted network clustering on spectral content and interclick interval of clicks, we determined the properties of a primary cluster of clicks with similar characteristics per site. These were compared within regions and across ocean basins and evaluated for suitability as population-level indicators.

Results

Spectral averages obtained from primary clusters of echolocation clicks identified at each site were similar in overall shape but varied in peak frequency by up to 8 kHz. We identified a latitudinal cline, with higher peak frequencies occurring in lower latitudes.

Main conclusions

It may be possible to acoustically delineate populations of Blainville's beaked whales. The documented negative correlation between signal peak frequency and latitude could relate to body size. Body size has been shown to influence signal frequency, with lower frequencies produced by larger animals, which are subsequently more common in higher latitudes for some species, although data are lacking to adequately investigate this for beaked whales. Prey size and depth may shape frequency content of echolocation signals, and larger prey items may occur in higher latitudes, resulting in lower signal frequencies of their predators.     

The evolution and ecology of multiple antipredator defences

Prey seldom rely on a single type of antipredator defence, often using multiple defences to avoid predation. In many cases, selection in different contexts may favour the evolution of multiple defences in a prey. However, a prey may use multiple defences to protect itself during a single predator encounter. Such “defence portfolios” that defend prey against a single instance of predation are distributed across and within successive stages of the predation sequence (encounter, detection, identification, approach (attack), subjugation and consumption). We contend that at present, our understanding of defence portfolio evolution is incomplete, and seen from the fragmentary perspective of specific sensory systems (e.g., visual) or specific types of defences (especially aposematism). In this review, we aim to build a comprehensive framework for conceptualizing the evolution of multiple prey defences, beginning with hypotheses for the evolution of multiple defences in general, and defence portfolios in particular. We then examine idealized models of resource trade-offs and functional interactions between traits, along with evidence supporting them. We find that defence portfolios are constrained by resource allocation to other aspects of life history, as well as functional incompatibilities between different defences. We also find that selection is likely to favour combinations of defences that have synergistic effects on predator behaviour and prey survival. Next, we examine specific aspects of prey ecology, genetics and development, and predator cognition that modify the predictions of current hypotheses or introduce competing hypotheses. We outline schema for gathering data on the distribution of prey defences across species and geography, determining how multiple defences are produced, and testing the proximate mechanisms by which multiple prey defences impact predator behaviour. Adopting these approaches will strengthen our understanding of multiple defensive strategies.     

Mating success and oviposition of a butterfly are not affected by non-lethal tissue sampling

Non-lethal methods of tissue sampling are increasingly used for genetic studies of insect species and the effects of this approach have long been assumed to be minimal. Tissue removal has the potential to influence insect reproductive behaviours such as mate recognition, courtship or oviposition but the effects of non-lethal sampling on reproductive success have not been widely and adequately tested. Here, we test potential effects of both wing-clipping and leg removal on reproductive behaviours of the cabbage white butterfly (Pieris rapae). We conducted a total of 93 male and 59 female mating trials, and found no significant differences in mating success between treated (i.e., tissue removed) and control individuals in either sex. We also monitored the number and location of eggs laid by 58 females. We found no significant differences in egg-laying behaviour among leg removed and control individuals. Power analysis indicated that we had sufficient statistical power to detect moderate effects of treatment on both mating and oviposition. Our study provides the most comprehensive examination to date of the effects of non-lethal sampling on reproductive behaviours in a butterfly/insect species, and supports the contention that tissue sampling is non-detrimental. To fully comprehend the general impacts of tissue sampling on butterfly reproductive behaviour however, additional similar studies need to be conducted on a variety of species with differing mating behaviours. Only through meta-analysis, may it be possible to detect more subtle effects of tissue removal which cannot be revealed within a single study due to sample size limitations.     

Safety and immunomodulatory effects of allogeneic canine adipose-derived mesenchymal stromal cells transplanted into the region of the lacrimal gland,the gland of the third eyelid and the knee joint

Background aimsMesenchymal stromal cells (MSCs) have been extensively studied as a cellular therapeutic for various pathologic conditions. However, there remains a paucity of data regarding regional and systemic safety of MSC transplantations, particularly with multiple deliveries of allogeneic cells. The purpose of this study was to investigate the safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs into the region of the lacrimal gland, the gland of the third eyelid and the knee joint in dogs.MethodsAllogeneic adipose tissue-derived canine MSCs were delivered to the regions of the lacrimal gland and the third eyelid gland as well as in the knee joints of six healthy laboratory beagles as follows: six times with 1-week intervals for delivery to the lacrimal gland and the third eyelid gland regions and three to four times with 1- to 2-week intervals for intra-articular transplantations. Dogs were sequentially evaluated by clinical examination. At the conclusion of the study, dogs were humanely euthanized, and a complete gross and histopathologic examination of all organ systems was performed. Mixed leukocyte reactions were also performed before the first transplantation and after the final transplantation.ResultsClinical and pathologic examinations found no severe consequences after repeated MSC transplantations. Results of mixed leukocyte reactions demonstrated suppression of T-cell proliferation after MSC transplantations.ConclusionsThis is the first study to demonstrate regional and systemic safety and systemic immunomodulatory effects of repeated local delivery of allogeneic MSCs in vivo.     

Why did eukaryotes evolve only once? Genetic and energetic aspects of conflict and conflict mediation

According to multi-level theory, evolutionary transitions require mediating conflicts between lower-level units in favour of the higher-level unit. By this view, the origin of eukaryotes and the origin of multicellularity would seem largely equivalent. Yet, eukaryotes evolved only once in the history of life, whereas multicellular eukaryotes have evolved many times. Examining conflicts between evolutionary units and mechanisms that mediate these conflicts can illuminate these differences. Energy-converting endosymbionts that allow eukaryotes to transcend surface-to-volume constraints also can allocate energy into their own selfish replication. This principal conflict in the origin of eukaryotes can be mediated by genetic or energetic mechanisms. Genome transfer diminishes the heritable variation of the symbiont, but requires the de novo evolution of the protein-import apparatus and was opposed by selection for selfish symbionts. By contrast, metabolic signalling is a shared primitive feature of all cells. Redox state of the cytosol is an emergent feature that cannot be subverted by an individual symbiont. Hypothetical scenarios illustrate how metabolic regulation may have mediated the conflicts inherent at different stages in the origin of eukaryotes. Aspects of metabolic regulation may have subsequently been coopted from within-cell to between-cell pathways, allowing multicellularity to emerge repeatedly.     

A Conserved Role for Atlastin GTPases in Regulating Lipid Droplet Size

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