Regeneration in vertebrates

One way or another, all species possess the ability to regenerate damaged tissues. The degree of regeneration, however, varies considerably among tissues within a body and among species, with urodeles being the most spectacular. Such differences in regenerative capacity are indicative of specific mechanisms that control the different types of regeneration. In this review the different types of regeneration in vertebrates and their basic characteristics are presented. The major cellular events, such as dedifferentiation and transdifferentiation, which allow complex organ and body part regeneration, are discussed and common molecular mechanisms are pinpointed.     

Resource polymorphisms in vertebrates

Discrete resource polymorphisms occur in various vertebrate species and probably occur more frequently than is generally appreciated. They are manifested in a number of ways, including morphological, behavioral and life history characters. Research on a number of unrelated taxa suggests that resource polymorphisms may be underestimated as a diversifying force and potentially play important roles in population divergence and initial steps in speciation. In an ecological context, they are important in resource partitioning and reducing intraspecific competition. Recent research suggests that the mechanisms maintaining these polymorphisms may be similar in diverse taxa, that phenotypic plasticity is important, and that some are under simple genetic control.     

Left-right asymmetry in vertebrates

A mechanism for the generation of the morphological left-right asymmetry in higher organisms is proposed, based on the idea that chirality at the molecular level is the primordial source for macroscopic asymmetry. This mechanism accounts for a variety of experimental results on artificial production of situs inversus and fits well with mutations in mice causing visceral transposition.     

Mechanisms of group-hunting in vertebrates

Group-hunting is ubiquitous across animal taxa and has received considerable attention in the context of its functions. By contrast much less is known about the mechanisms by which grouping predators hunt their prey. This is primarily due to a lack of experimental manipulation alongside logistical difficulties quantifying the behaviour of multiple predators at high spatiotemporal resolution as they search, select, and capture wild prey. However, the use of new remote-sensing technologies and a broadening of the focal taxa beyond apex predators provides researchers with a great opportunity to discern accurately how multiple predators hunt together and not just whether doing so provides hunters with a per capita benefit. We incorporate many ideas from collective behaviour and locomotion throughout this review to make testable predictions for future researchers and pay particular attention to the role that computer simulation can play in a feedback loop with empirical data collection. Our review of the literature showed that the breadth of predator:prey size ratios among the taxa that can be considered to hunt as a group is very large (<10⁰ to >10²). We therefore synthesised the literature with respect to these predator:prey ratios and found that they promoted different hunting mechanisms. Additionally, these different hunting mechanisms are also related to particular stages of the hunt (search, selection, capture) and thus we structure our review in accordance with these two factors (stage of the hunt and predator:prey size ratio). We identify several novel group-hunting mechanisms which are largely untested, particularly under field conditions, and we also highlight a range of potential study organisms that are amenable to experimental testing of these mechanisms in connection with tracking technology. We believe that a combination of new hypotheses, study systems and methodological approaches should help push the field of group-hunting in new directions.     

Vestibulospinal system organization in vertebrates

The data on the vestibular nuclear complex and vestibulospinal systems in vertebrates are reviewed. Literature data on the topography, structure, and fiber connections of vestibular cell groups forming descending projections and the effects on the spinal cord and skeletal muscles are summarized. Current conceptions of the structural and functional specificity of different vestibulospinal systems are discussed.O. O. Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 24, No. 2, pp. 215–238, March–April, 1992.     

Cardiac regeneration in non-mammalian vertebrates

The heart is a robust organ, capable of pumping nutrients and transferring oxygen throughout the body via a network of capillaries, veins and arteries, for the entirety of a human's life. However, the fragility of mammalian hearts is also evident when it becomes damaged and parts of the organ fail to function. This is due to the fact that rather than replenishing the damaged areas with functional cellular mass, fibrotic scar tissue is the preferred replacement, resulting in an organ with functional deficiencies. Due to the mammalian hearts incapability to regenerate following damage and the ever-increasing number of people worldwide suffering from heart disease, tireless efforts are being made to discover ways of inducing a regenerative response in this most important organ. One such avenue of investigation involves studying our distantly related non-mammalian vertebrate cousins, which over the last decade has proved to us that cardiac regeneration is possible. This review will highlight these organisms and provide insights into some of the seminal discoveries made in the heart regeneration field using these amazing chordates.