Biological Reviews最新文献

Intervertebral disc degeneration (IDD) can contribute to lower back and neck pain. In IDD, the most affected component of the intervertebral disc is the nucleus pulposus (NP). Derived from the notochord, where cells are organized into a tandem configuration, young NP cells cluster in three-dimensional (3D) networks embedded in a gelatinous matrix. Here, we review the current understanding of NP development, homeostasis, physiology, and degeneration with a focus on the roles of the cell adhesion molecule N-cadherin in these processes. Based on the literature, we hypothesize that N-cadherin contributes to the architectural transition from the notochord to the NP by mediating a switch in cellular organization from tandem to random orientational cell adhesions (OCAs). We further hypothesize that the 3D clustering of NP cells may facilitate N-cadherin to act as a mechanosensor to modulate NP gene expression under mechanical stresses. We hope these hypotheses promote future research on the etiology of human IDD and the development of measures to prevent and treat IDD. Some open questions on N-cadherin functions in the NP are also discussed.

Mass mortality events (MMEs) have been occurring since the dawn of time. However, in contrast to terrestrial events, most marine MMEs remain undetected, largely due to the inaccessibility of many marine environments. One of the most notorious and best-studied marine MMEs in modern times is that of the population collapse of the echinoid Diadema antillarum in the Caribbean Sea during the mid-1980s, which triggered a catastrophic phase shift in local benthic communities from which the region never fully recovered – illustrating the ecological significance of echinoids in maintaining marine habitat stability. In recent years echinoid MMEs have reached an unprecedented scale, affecting populations across multiple ocean basins, climatic regions, and taxonomic range. Most recently, pathogenic-driven mortalities spreading from the Caribbean to the Mediterranean and Red Sea and further expanding into the Indo-Pacific, pose a significant threat to ecological integrity across thousands of kilometres. The apparent intensification of global echinoid MMEs underscores the urgency of elucidating the mechanisms driving these events and their implications for marine conservation.

Here we present a comprehensive review of global echinoid MMEs, including scientific literature dating back to 1888. We identify and formulate the five main mechanisms driving echinoid MMEs: (i) pathogens (33%); (ii) catastrophic events (25%); (iii) harmful algal blooms (11%); (iv) extreme temperatures and tides (24%); and (v) human activities (7%). We then explore spatio-temporal trends and the underlying functional morphology traits that drive these events.

In social species, group functions often benefit from variation among individual group members. Many highly integrated social insect colonies rely on division of labour among colony members and emergent properties of their collective behaviour and physiology. Response threshold models are a prominent proximate explanation of division of labour, but how variation in response thresholds arise is largely unexplored. We propose the Weak Worker Hypothesis, a novel conceptual framework suggesting that response thresholds are determined by an individual's susceptibility to the stressor that underlies the task. Thus, specific tasks are preferentially performed, or at least initiated, by the individuals that are most susceptible to the corresponding stressor. Consequently, ‘weak’ workers that are susceptible to a particular stressor play a disproportionate role in the group's defence against this stressor. The response threshold manifests as an internal evaluation of a task-specific stimulus that is influenced by the severity of the physiological perturbation of the individual, which simultaneously determines the susceptibility of this individual to succumb to the external disturbance. As long as individual stress susceptibilities vary among different stressors, this model generates division of labour and thus group stability. The Weak Worker Hypothesis provides a functional explanation for individual-level responses to environmental deviations from optimal conditions. Such a deviation could be directly perceived as stimulus and simultaneously lead to physiological stress, or the physiological stress caused by the deviation could be the stimulus itself. In support of the Weak Worker Hypothesis, we present experimental evidence of a link between individual heat susceptibility and fanning behaviour in honey bees (Apis mellifera L.). We also discuss other possible cases and how to test our idea empirically in other contexts, keeping in mind the important distinction between cause and consequence. Finally, we conclude that the Weak Worker Hypothesis could provide a useful extension of response threshold models for understanding the division of labour in social groups, which might have repercussions for applied social insect science, selective breeding and eradication efforts.

Hill, M. & Hill, A. (2012). The magnesium inhibition and arrested phagosome hypotheses: new perspectives on the evolution and ecology of Symbiodinium symbioses. Biological Reviews 87, 804-821. https://doi.org/10.1111/j.1469-185X.2012.00223.x

In the originally published online version, the first and last names of the authors were erroneously transposed. The correct names are:

Malcolm Hill and April Hill

The online version has been corrected accordingly.

We apologize for this error.

Biological invasions are one of the major drivers of biodiversity decline and have been shown to have far-reaching consequences for society and the economy. Preventing the introduction and spread of alien species represents the most effective solution to reducing their impacts on nature and human well-being. However, implementing effective solutions requires a good understanding of where the species are established and how biological invasions develop over time. Knowledge of the status and trends of biological invasions is thus key for guiding research efforts, informing stakeholders and policymakers, for targeted management efforts, and preparing for the future. However, information about the status and trends of alien species is scattered, patchy, and highly incomplete, making it difficult to assess. Published reports for individual regions and taxonomic groups are available, but large-scale overviews are scarce. A global assessment therefore requires a review of available knowledge with careful consideration of sampling and reporting biases. This paper provides a comprehensive global assessment of the status and trends of alien species for major taxonomic groups [Bacteria, Protozoa, Stramenopila, Alveolata, and Rhizaria (SAR), fungi, plants, and animals] for Intergovernmental Panel of Biodiversity and Ecosystem Services (IPBES) regions.

The review provides irrefutable evidence that alien species have been introduced to all regions worldwide including Antarctica and have spread to even the most remote islands. The numbers of alien species are increasing within all taxa and across all regions, and are often even accelerating. Large knowledge gaps exist, particularly for taxonomic groups other than vascular plants and vertebrates, for regions in Africa and Central Asia, and for aquatic realms. In fact, for inconspicuous species, such as Bacteria, Protozoa, and to some degree SAR and fungi, we found records for very few species and regions. Observed status and trends are thus highly influenced by research effort. More generally, it is likely that all lists for alien species of any taxonomic group and region are incomplete. The reported species numbers therefore represent minima, and we can expect additions to all lists in the near future. We identified six key challenges which need to be addressed to reduce knowledge gaps and to improve our ability to assess trends and status of biological invasions.