Tissue Microenvironments Define and Get Reinforced by Macrophage Phenotypes in Homeostasis or during Inflammation, Repair and Fibrosis

Current macrophage phenotype classifications are based on distinct in vitro culture conditions that do not adequately mirror complex tissue environments. In vivo monocyte progenitors populate all tissues for immune surveillance which supports the maintenance of homeostasis as well as regaining homeostasis after injury. Here we propose to classify macrophage phenotypes according to prototypical tissue environments, e.g. as they occur during homeostasis as well as during the different phases of (dermal) wound healing. In tissue necrosis and/or infection, damage- and/or pathogen-associated molecular patterns induce proinflammatory macrophages by Toll-like receptors or inflammasomes. Such classically activated macrophages contribute to further tissue inflammation and damage. Apoptotic cells and antiinflammatory cytokines dominate in postinflammatory tissues which induce macrophages to produce more antiinflammatory mediators. Similarly, tumor-associated macrophages also confer immunosuppression in tumor stroma. Insufficient parenchymal healing despite abundant growth factors pushes macrophages to gain a profibrotic phenotype and promote fibrocyte recruitment which both enforce tissue scarring. Ischemic scars are largely devoid of cytokines and growth factors so that fibrolytic macrophages that predominantly secrete proteases digest the excess extracellular matrix. Together, macrophages stabilize their surrounding tissue microenvironments by adapting different phenotypes as feed-forward mechanisms to maintain tissue homeostasis or regain it following injury. Furthermore, macrophage heterogeneity in healthy or injured tissues mirrors spatial and temporal differences in microenvironments during the various stages of tissue injury and repair. Copyright (C) 2012 S. Karger AG, Base

Palaeoclimatic implications of the occurrence of the arcoid bivalve Anadara trapezia (Deshayes) in the Quaternary of Australasia

The arcoid bivalve Anadara trapezia (Deshayes, 1840) is a eurythermal estuarine mollusc that flourishes at present in eastern Australia between Port Phillip Bay, Victoria and Townsville in northern Queensland. A. trapezia first appeared in the Australian Quaternary fossil record during Oxygen Isotope Stage (OIS) 7. In New Zealand, where it is now extinct, the earliest known occurrences are in the Rangitawa 'fossil beds' and in uppermost Castlecliffian strata west of Wanganui, North Island (OIS 11, ca. 400 ka). The species had an extensive distribution during the Last Interglacial Maximum (OIS 5e) in both Australia and New Zealand and appears to have had a slightly wider than present geographic range in southeastern Australia during the Middle Holocene, as shown by records from Tasmania and western Victoria, where it no longer lives. Apart from an isolated population inhabiting Oyster Harbour, Western Australia, A. trapezia has not been confirmed living in coastal waters west of Port Phillip Bay, Victoria. It became extinct in New Zealand sometime after OIS 5e. The extensive distribution and abundance of A. trapezia and other fauna of subtropical affinity during the Last Interglacial Maximum, in areas where both are now extinct, appears to be associated with an enhanced Leeuwin Current at that time, coinciding with higher, less seasonally concentrated levels of precipitation and river discharge. The arrival of A. trapezia in Australasian coastal waters may have been a consequence of planktonic dispersal from southern South America. A. bravardi del Rio, from the Middle Miocene Puerto Madryn Formation, on the Valdes Peninsula, Argentina, may be a possible ancestor for A. trapezia. (C) 2000 Elsevier Science Ltd

Holocene freshwater history of the Lower River Murray and its terminal lakes, Alexandrina and Albert, South Australia, and its relevance to contemporary environmental management

Recent claims based on hydrodynamic modelling within a sequence stratigraphical perspective of incised valley fill sedimentation have argued that the Lower River Murray and its terminal lakes Alexandrina and Albert represented a marine–estuarine lake system, with marine salinities for some 200 km upstream from the Murray Mouth. These claims have encouraged proposals for the removal of barrages near the Murray Mouth to restore the ‘original natural condition’ of the lakes. It has also been suggested that fine-grained terrestrial sediments were trapped in this mega-lake, necessitating a re-assessment of the Holocene climatic history of southeastern Australia determined from the study of continental slope cores. We show that throughout Holocene time (the past 11.7 ka), the Lower River Murray remained a freshwater-dominated system, based on a range of mutually complementary sedimentary evidence. Radiocarbon dating of Aboriginal middens adjacent to the river and lakes comprising freshwater mussels (dominantly Velesunio ambiguous), crayfish (Euastacus armatus), turtles (Emydura macquarii) and otoliths of freshwater fish species, such as Murray cod (Maccullochella peelii), confirm freshwater riverine and lacustrine conditions throughout the Holocene. Lake Alexandrina also contains endemic obligate freshwater fishes, including a genetically divergent and locally adapted lineage of southern pygmy perch (Nannorpeca australis), revealing an evolutionary history linked to freshwater habitat in the lakes since the late Pleistocene. Freshwater diatoms from fine-grained fluvial clay successions at Riverglen Marina, and diatoms and lacustrine sediments, including sapropels in the lower lakes and their former embayments of Cooke Plains and Waltowa Swamp, also chronicle a history of freshwater deposition. Lakeshore ridges of terrestrially derived quartz sand formed during elevated freshwater lake levels 8.0 ± 1.2 ka ago, while consolidated masses of the freshwater clam Corbicula australis, radiocarbon dated at 2650 ± 90 year BP, also attest to long-term freshwater conditions. An open Murray Mouth is prima facie evidence for sustained river discharge, and the mouth remained open throughout the Holocene based on geomorphological evidence. The barrages that were built to retain freshwater within the lower lakes, in response to upstream water abstractions, which had reduced river flows, provide the closest analogue of the ‘original’ conditions of this environment. With increased automation, nuanced barrage operation could even better simulate the original environment, whereas removing the barrages and building a weir at Wellington would destroy the character of this internationally significant Ramsar Wetland, with detrimental impacts farther upstream.KEY POINTS Paleoclimatic, geomorphological and modelling reconstructions, together with sedimentary records based on freshwater diatoms, molluscs, fish, turtles and lacustrine systems and evidence of genetically divergent and locally adapted obligate freshwater fishes, demonstrate that predominantly freshwater conditions were present in the Lower River Murray and its terminal lakes throughout Holocene time (11.7 ka). The empirical observations presented in this paper reveal that a large marine-dominated mid-Holocene estuary was not present in the Lower River Murray, Australia. Proposals to remove the barrages near the Murray Mouth would destroy the long-term freshwater environment of this Internationally Significant Wetland Site with negative ecological impacts.No Full Tex