Species Richness and Trophic Diversity Increase Decomposition in a Co-Evolved Food Web

Ecological communities show great variation in species richness, composition and food web structure across similar and diverse ecosystems. Knowledge of how this biodiversity relates to ecosystem functioning is important for understanding the maintenance of diversity and the potential effects of species losses and gains on ecosystems. While research often focuses on how variation in species richness influences ecosystem processes, assessing species richness in a food web context can provide further insight into the relationship between diversity and ecosystem functioning and elucidate potential mechanisms underpinning this relationship. Here, we assessed how species richness and trophic diversity affect decomposition rates in a complete aquatic food web: the five trophic level web that occurs within water-filled leaves of the northern pitcher plant, Sarracenia purpurea. We identified a trophic cascade in which top-predators — larvae of the pitcher-plant mosquito — indirectly increased bacterial decomposition by preying on bactivorous protozoa. Our data also revealed a facultative relationship in which larvae of the pitcher-plant midge increased bacterial decomposition by shredding detritus. These important interactions occur only in food webs with high trophic diversity, which in turn only occur in food webs with high species richness. We show that species richness and trophic diversity underlie strong linkages between food web structure and dynamics that influence ecosystem functioning. The importance of trophic diversity and species interactions in determining how biodiversity relates to ecosystem functioning suggests that simply focusing on species richness does not give a complete picture as to how ecosystems may change with the loss or gain of species

Phospholipase D signaling: orchestration by PIP2 and small GTPases

Hydrolysis of phosphatidylcholine by phospholipase D (PLD) leads to the generation of the versatile lipid second messenger, phosphatidic acid (PA), which is involved in fundamental cellular processes, including membrane trafficking, actin cytoskeleton remodeling, cell proliferation and cell survival. PLD activity can be dramatically stimulated by a large number of cell surface receptors and is elaborately regulated by intracellular factors, including protein kinase C isoforms, small GTPases of the ARF, Rho and Ras families and, particularly, by the phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 is well known as substrate for the generation of second messengers by phospholipase C, but is now also understood to recruit and/or activate a variety of actin regulatory proteins, ion channels and other signaling proteins, including PLD, by direct interaction. The synthesis of PIP2 by phosphoinositide 5-kinase (PIP5K) isoforms is tightly regulated by small GTPases and, interestingly, by PA as well, and the concerted formation of PIP2 and PA has been shown to mediate receptor-regulated cellular events. This review highlights the regulation of PLD by membrane receptors, and describes how the close encounter of PLD and PIP5K isoforms with small GTPases permits the execution of specific cellular functions

Genomic reconstruction of the SARS-CoV-2 epidemic in England.

The evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus leads to new variants that warrant timely epidemiological characterization. Here we use the dense genomic surveillance data generated by the COVID-19 Genomics UK Consortium to reconstruct the dynamics of 71 different lineages in each of 315 English local authorities between September 2020 and June 2021. This analysis reveals a series of subepidemics that peaked in early autumn 2020, followed by a jump in transmissibility of the B.1.1.7/Alpha lineage. The Alpha variant grew when other lineages declined during the second national lockdown and regionally tiered restrictions between November and December 2020. A third more stringent national lockdown suppressed the Alpha variant and eliminated nearly all other lineages in early 2021. Yet a series of variants (most of which contained the spike E484K mutation) defied these trends and persisted at moderately increasing proportions. However, by accounting for sustained introductions, we found that the transmissibility of these variants is unlikely to have exceeded the transmissibility of the Alpha variant. Finally, B.1.617.2/Delta was repeatedly introduced in England and grew rapidly in early summer 2021, constituting approximately 98% of sampled SARS-CoV-2 genomes on 26 June 2021

Atuação da cirurgia plástica no tratamento de feridas complexas

OBJETIVO: Relatar a atuação da Cirurgia Plástica no tratamento das feridas complexas em hospital terciário, analisando suas características, tipos de lesões e condutas adotadas, com ênfase no tratamento cirúrgico. MÉTODOS: Análise retrospectiva dos pacientes com feridas complexas atendidos pela Cirurgia Plástica em hospital terciário, através dos pedidos de consulta, em um período de cinco anos (2006 a 2010). A coleta dos dados foi obtida a partir de atendimentos realizados, avaliações seriadas e registros do prontuário médico. RESULTADOS: Foram atendidos 1927 pacientes (32 consultas/mês), com média de idade de 46,3 anos, predominando o sexo masculino (62%). As especialidades cirúrgicas solicitaram 1076 consultas (56%) e as clínicas, 851 (44%). A distribuição por tipo de ferida demonstrou predomínio das úlceras por pressão (635/33%), das feridas traumáticas (570/30%), cirúrgicas complicadas (305/16%) e necrotizantes (196/10%), sendo o restante representado por vasculite (83/4%), úlceras venosas (79/4%), diabéticas (41/2%) e pós-radiação (18/1%). O tratamento foi operatório em 1382 pacientes (72%) e não-operatório em 545 casos (28%). Nos pacientes operados, realizaram-se 3029 operações, predominando os desbridamentos (1988/65%) e enxertias de pele (619/21%) associadas ou não com a terapia por pressão negativa (vácuo), seguido pelos retalhos pediculados (237/8%), reimplantes digitais (81/3%), retalhos microcirúrgicos (66/2%) e outros procedimentos (38/1%). CONCLUSÃO: O cirurgião plástico demonstrou ter importante atuação no tratamento das feridas complexas por adotar o tratamento cirúrgico mais precocemente, colaborando para a efetiva resolução dos casos