滨海湿地生态系统微生物驱动的氮循环研究进展

滨海湿地生态系统介于陆地生态系统和海洋生态系统之间,其类型多种多样,环境差异极大,微生物种类丰富。近年来,随着人为氮源的大量输入,造成滨海湿地生态系统富营养化污染问题日趋严重。本文主要总结了滨海湿地生态系统微生物驱动的固氮、硝化、反硝化、厌氧氨氧化、NO_3~-还原成铵等主要氮循环过程,并综述了通过功能基因(如nifH、amoA、hzo、nirS、nirK、nrfA)检测微生物群落多样性及其环境影响因素的相关研究,旨在更好理解微生物驱动氮循环过程以去除氮,以期为减轻富营养化和危害性藻类爆发提供科学依据。     

The effect of input pressure and flow on the pattern and resistance to flow in the isolated perfused gill of a teleost fish

Summary When an isolated gill arch of the marine teleost,Ophiodon elongatus, was perfused under conditions which mimic those present in the intact animal, only two thirds of the gill lamellae were perfused. An increase in either input (afferent) pressure and flow or input pulse pressure caused an increase in the number of lamellae perfused as well as altering the distribution of the efferent outflow between the efferent artery and the venolymphatic drainage of the gill. The gill is compliant and an increase in efferent pressure reduced gill resistance to flow without altering the number of lamellae perfused. In these experiments there was no simple relationship between the number of lamellae perfused and gill resistance.These observations are of importance in the interpretation of results from pharmacological and ion exchange studies of isolated gills as well as indicating how cardiovascular changes could bring about alterations in gill blood flow in the intact fish.     

Antiviral activity of selected medicinal plants and marine seaweeds on the grasserie infected larvae of silkworm,Bombyx mori

Nuclear polyhedrosis virus (NPV) is the most harmful virus responsible for the manifestation of grasserie disease in the larvae of silkworm, Bombyx mori. It causes a huge economic loss in the sericulture industry. An attempt was made in the present investigation for the screening of antiviral activity using medicinal plants such as Lantana camara, Phyllanthus amarus and marine seaweeds such as Sargassum wightii, Turbinaria ornata against BmNPV. Crude extracts were prepared using different solvents, such as hexane, ethyl acetate, methanol and water. The silkworm feeding bioassay study was carried out with the crude extracts to investigate the presence of anti-BmNPV activity after inoculating fifth instar larvae of silkworm with occlusion bodies (OBs) of BmNPV. Each extract was tested for their anti-BmNPV activity using various concentrations of crude extracts ranging from 200 μg to 1000 μg. Among the crude extracts tested, methanol and aqueous extracts of P. amarus showed significant anti-BmNPV activity.     

Cyanotoxins from Black Band Disease of Corals and from Other Coral Reef Environments

Many cyanobacteria produce cyanotoxins, which has been well documented from freshwater environments but not investigated to the same extent in marine environments. Cyanobacteria are an obligate component of the polymicrobial disease of corals known as black band disease (BBD). Cyanotoxins were previously shown to be present in field samples of BBD and in a limited number of BBD cyanobacterial cultures. These toxins were suggested as one of the mechanisms contributing to BBD-associated coral tissue lysis and death. In this work, we tested nine cyanobacterial isolates from BBD and additionally nine isolated from non-BBD marine sources for their ability to produce toxins. The presence of toxins was determined using cell extracts of laboratory grown cyanobacterial cultures using ELISA and the PP2A assay. Based on these tests, it was shown that cyanobacterial toxins belonging to the microcystin/nodularin group were produced by cyanobacteria originating from both BBD and non-BBD sources. Several environmental factors that can be encountered in the highly dynamic microenvironment of BBD were tested for their effect on both cyanobacterial growth yield and rate of toxin production using two of the BBD isolates of the genera Leptolyngbya and Geitlerinema. While toxin production was the highest under mixotrophic conditions (light and glucose) for the Leptolyngbya isolate, it was highest under photoautotrophic conditions for the Geitlerinema isolate. Our results show that toxin production among marine cyanobacteria is more widespread than previously documented, and we present data showing three marine cyanobacterial genera (Phormidium, Pseudanabaena, and Spirulina) are newly identified as cyanotoxin producers. We also show that cyanotoxin production by BBD cyanobacteria can be affected by environmental factors that are present in the microenvironment associated with this coral disease.     

Communicating (gap) junctions between chloride cells in the gill epithelium of the lamprey,Geotria australis

Summary Freeze-fracture replicas show that communicating (gap) junctions are present between chloride cells in the gill epithelium of young adults of the Southern Hemisphere lamprey, Geotria australis, acclimated to full-strength sea water. The junctions, which were already present when these lampreys were migrating downstream, may help coordinate the secretory activities of the chloride cells during the marine phase of the lamprey life cycle.     

Why are there so few freshwater fish species in most estuaries?

The freshwater fish assemblage in most estuaries is not as species rich as the marine assemblage in the same systems. Coupled with this differential richness is an apparent inability by most freshwater fish species to penetrate estuarine zones that are mesohaline (salinity: 5·0–17·9), polyhaline (salinity: 18·0–29·9) or euhaline (salinity: 30·0–39·9). The reason why mesohaline waters are avoided by most freshwater fishes is difficult to explain from a physiological perspective as many of these species would be isosmotic within this salinity range. Perhaps, a key to the poor penetration of estuarine waters by freshwater taxa is an inability to develop chloride cells in gill filament epithelia, as well as a lack of other osmoregulatory adaptations present in euryhaline fishes. Only a few freshwater fish species, especially some of those belonging to the family Cichlidae, have become fully euryhaline and have successfully occupied a wide range of estuaries, sometimes even dominating in hyperhaline systems (salinity 40+). Indeed, this review found that there are few fish species that can be termed holohaline (i.e. capable of occupying waters with a salinity range of 0–100+) and, of these taxa, there is a disproportionally high number of freshwater species (e.g. Cyprinodon variegatus, Oreochromis mossambicus and Sarotherodon melanotheron). Factors such as increased competition for food and higher predation rates by piscivorous fishes and birds may also play an important role in the low species richness and abundance of freshwater taxa in estuaries. Added to this is the relatively low species richness of freshwater fishes in river catchments when compared with the normally higher diversity of marine fish species for potential estuarine colonization from the adjacent coastal waters. The almost complete absence of freshwater fish larvae from the estuarine ichthyoplankton further reinforces the poor representation of this guild within these systems. An explanation as to why more freshwater fish species have not become euryhaline and occupied a wide range of estuaries similar to their marine counterparts is probably due to a combination of the above described factors, with physiological restrictions pertaining to limited salinity tolerances probably playing the most important role.     

X-cell gill disease in Pagothenia borchgrevinki from McMurdo Sound, Antarctica

The Antarctic nototheniid fish Pagothenia borchgrevinki is a schooling, cryopelagic fish growing to about 280 mm maximum length. It is affected by X-cell disease, which causes gross swelling of gill filaments. Overall, 22% of the fish sampled had X-cell disease with individual schools ranging from 9.2 to 43.9%, which is a very high incidence compared to figures of other fish with the disease. In P. borchgrevinki, the disease caused a doubling of gill mass but had no effect on liver mass. Condition factor of affected fish was low. Received: 24 March 1997 / Accepted: 12 July 1997     

Paroxysmal and cognitive phenotypes in Prrt2 mutant mice

Mutations in proline‐rich transmembrane protein 2 (PRRT2) cause a range of episodic disorders that include paroxysmal kinesigenic dyskinesia and benign familial infantile epilepsy. Mutations are generally loss of function and include the c649dupC frameshifting mutation that is present in around 80% of affected individuals. To investigate how Prrt2 loss of function mutations causes disease, we performed a phenotypic investigation of a transgenic Prrt2 knockout (Prrt2 KO) mouse. We observed spontaneous paroxysmal episodes with behavioural features of both seizure and movement disorders, as well as unexplained deaths in KO and HET animals. KO mice showed spatial learning deficits in the Morris water maze, as well as gait abnormalities in the quantitative Digigait analysis; both of which may be representative of the more severe phenotypes experienced by homozygous patients. These findings extend the described phenotypes of Prrt2 mutant mice, further confirming their utility for in vivo investigation of the role of Prrt2 mutations in episodic diseases.     

Deleterious effect of Chattonella marina on short-necked clam (Ruditapes philippinarum); possible involvement of reactive oxygen species

In laboratory exposure experiments, Chattonella marina showeda deleterious effect on short-necked clams (Ruditapes philippinarum).Accumulated C. marina cells were observed in gill tissues ofthe clams exposed to C. marina. Immunohistochemical analysisusing antiserum against the crude glycocalyx of C. marina suggestedthat the glycocalyx was present on the gill surface. Mucus substancesprepared from gill tissue of the clams stimulated C. marinato generate increased amounts of O₂^– in a concentration-dependentmanner. These results suggest that reactive oxygen species (ROS)-mediatedgill tissue damage is one of the causative factors responsiblefor the harmful effect of C. marina on shellfish.     

Neoparamoebic gill infections: host response and physiology in salmonids

Amoebic gill diseases (AGD) caused primarily by the amphizoic Neoparamoeba spp. have been identified as significant to fish health in intensive aquaculture. These diseases have consequently received significant attention with regard to disease pathophysiology. Neoparamoeba perurans has been putatively identified as the aetiological agent in salmonids, with other species such as turbot Psetta maxima and sea bass Dicentrarchus labrax also affected. Similarly, Neoparamoeba spp. have also been identified in co‐infections with other gill diseases in salmonids. While infection of the gills results in an acute multifocal hyperplastic host response, reduced gill surface area and increased mucous cell densities, ion regulation and respiration in terms of blood gasses are only marginally affected. This may be partially attributed to reserve respiratory capacity and a reduction in mucous viscosity allowing for a greater flushing of the gill, so reducing the gill mucus boundary layer. Clinical and acute infections result in significant cardiovascular compromise with increases in aortic blood pressure, and systemic vascular resistance in Atlantic salmon, Salmo salar, which are not seen in rainbow Oncorhynchus mykiss and brown trout Salmo trutta. Increases in vascular resistance appear to be due to vascular constriction potentially reducing blood flow to the heart in compromised fishes, the overall effect being to lead to a compensatory tissue remodelling and change in cardiac shape in chronically infected fishes. The combined effect of reduced gill surface area and cardiovascular compromise leads to a significant reduction in swimming performance and increases in the routine metabolic rate that lead to an increase in the overall metabolic cost of disease.     

Aufwuchs Protozoa and Bacteria on the Gills of the Rock Crab,Cancer irroratus Say: A Survey by Light and Electron Microscopy1

Histological examination of gills of the rock crab (Cancer irroratus Say, 1917) taken from specimens collected in polluted and nonpolluted areas indicated that gill discoloration was not directly related to the degree of microbial fouling. Light microscope studies demonstrated that bacteria, peritrich and suctorian ciliates, and some naviculoid diatoms were the principal members of the fouling community. Examination of the bacteria by electron microscopy showed that several distinct types were present, and that some of these were attached to the gill by holdfast structures while others were enmeshed in a filamentous slime layer. An unusual small marine flagellate and an unidentified amoeba were also examined ultrastructurally.     

Biochemical and cytogenetic biomarkers of pollutant exposure in marine fish (Aldrichetta forsteri Valenciennes and Sillago schomburgkii Peters) near industrial and metropolitan centres in South Australia

This project aimed to measure biochemical and cytogenetic biomarkers in marine fish (Aldrichetta forsteri and Sillago schomburgkii) associated with industrial and urban centres in South Australia. These sites were Port Pirie (affected by metal-contaminated outflows), Barker Inlet (adjacent to Metropolitan Adelaide), and Wills Creek (reference site). The biochemical biomarkers included sorbitol dehydrogenase (SDH) and alanine aminotransferase (ALAT) in serum, adenylate levels (ATP, ADP and AMP) and adenylate energy charge (AEC) in gill and liver, and sodium/potassium ATPase (Na⁺, K⁺-ATPase) in gill. Erythrocyte micronucleus frequency was a marker of cytogenetic effect. Serum enzyme levels were generally higher in fish from Port Pirie and Barker Inlet than in those from Wills Creek, with SDH demonstrating the clearest site-associated differences. Tissue adenylates were consistently lower at Port Pirie than elsewhere, suggesting a greater metabolic strain in fish at this site. AEC in gill and liver were consistently lower at Port Pirie than at Wills Creek, with Barker Inlet generally between these two. The reversed rank order was observed with erythrocyte micronucleus frequencies. Seasonal variations in the biomarkers may be attributed either to seasonal physiological changes in fish or changes in pollutant input levels or compositions. Na⁺, K⁺-ATPase did not differ between sites nor seasons in this study. This work shows that biochemical and cytogenetic differences occur in marine fish at specific locations in South Australia. It also shows that of these tests, serum SDH and erythrocyte micronuclei are potentially the most sensitive and reliable biomarkers of pollutants effects on marine fish. The results also suggest that these data may be used as a baseline against which future changes in marine water quality, and their consequent biological effects, can be compared.     

First record of the occurrence of "gill disease" in Mytilus edulis trossulus from the Gulf of Gdańsk (Baltic Sea, Poland)

We are presenting the first report of the occurrence of "gill disease" in Mytilus edulis trossulus from the southern Baltic Sea, Gulf of Gdańsk (Poland). The disease preliminary diagnosis was based on the presence of white and yellow "spots" causing deep indentations in the gills with degeneration, destruction and necrosis of gill filaments. Average prevalence of gill erosion in the blue mussels population was 15.8%. According to other authors, gill erosion may affect over 80% of the bivalve population resulting in mortality rates of up to 40%. The origin of the gill erosion remains unknown, but viruses are most likely involved in the etiology of these pathological conditions. The disease as such may indicate a decrease in the immunological resistance of organisms to infections and inflammations directly or indirectly caused by harmful factors in the ambient environment. Furthermore, the occurrence of numerous pathologies in bivalves is a particular problem in the Gulf of Gdańsk being a low biodiversity ecosystem. Pathologies reduce bilvalves' reproduction ability, worsen their physiological condition and increase their mortality rate. Those factors may also pose a significant ecological danger and lead to negative alterations of the ecosystem.     

Mutagenic,genotoxic and bioaccumulative potentials of tannery effluents in freshwater fishes of River Ganga

The tannery industries are the reason of major environmental concerns as they release toxic heavy metals, like chromium, in rivers posing risks of genotoxicity and mutagenicity in aquatic organism and indirectly in humans through food chain. In the present analysis, the freshwater inhabitant fishes of River Ganges, viz., Labeo calbasu, Puntius sophore, and Mystus vittatus, were examined for assessing the genotoxic, mutagenic, and bioaccumulative potentials of tannery effluents. For genotoxicity assessment, the blood and gill samples of fishes prevailed from polluted sites of River Ganges adjoining Kanpur city were utilized for comet assay and micronucleus test. The present investigation revealed the presence of significantly (p < 0.05) higher micronuclei induction and % tail DNA in erythrocytes and gill cells of the fishes collected from the polluted sites. The bioaccumulation studies revealed chromium concentration in muscle (0.89 µg/g) and gill tissues (0.24 µg/g) of L. calbasu; muscle (0.44 µg/g) and gills (1.23 µg/g) of P. sophore; and muscle (0.9617 µg/g) and gills (0.3628 µg/g) of M. vittatus, quite higher than the permissible limits of the World Health Organization. Consequently, the present study indicates strongly that River Ganges is contaminated with harmful tannery pollutants causing genotoxicity and mutagenicity in freshwater fishes.     

Marine <Emphasis Type="Italic">Streptomyces</Emphasis> as a novel source of bioactive substances

Marine actinobacteria are the most economically as well as biotechnologically valuable prokaryotes. Representative genera of marine actinobacteria include Actinomadura, Aeromicrobium, Dietzia, Gordonia, Marinophilus, Micromonospora, Nonomuraea, Rhodococcus, Saccharomonospora, Saccharopolyspora, Salinispora, Streptomyces, Solwaraspora, Williamsia, Verrucosispora and several others. Among the genera of marine actinobacteria, the genus Streptomyces is represented in nature by the largest number of species and varieties, which differ greatly in their morphology, physiology, and biochemical activities. Marine Streptomyces occur in different biological sources such as fishes, molluscs, sponges, seaweeds and mangroves, besides seawater and sediments. In this review an evaluation is made on the present state of research on marine Streptomyces and its perspectives. The highlights include the production of metabolites such as antibiotics, anticancer compounds, enzymes, enzyme inhibitors and pigments by marine Streptomyces and their application as single cell protein and as probiotics in aquaculture. The marine environment contains a wide range of distinct Streptomyces that are not present in the terrestrial environment. With increasing advancement in science and technology, there would be greater demands in future for new bioactive compounds synthesised by Streptomyces from various marine sources.     

Flagellate Cryptobia branchialis (Bodonida: Kinetoplastida), ectoparasite of tilapia from the Salton Sea

An infestation of young tilapia, Oreochromis mossambicus Peters, by the flagellate Cryptobia branchialiswas observed at the Salton Sea, California, in September, 1997. This is the first report of C. branchialis in a highly saline water-body (43 g l^–1). Ultrastructure of C. branchialis as well as its effect on the gills of tilapia were studied using the scanning and transmission electron microscopy. No direct effect of C. branchialis on the epithelial cells of fish gills was observed. However, alterations of gill general structure, such as deposition of copious mucus on the gill surface, swelling of filaments, reduction of respiratory lamellae and their transformation into short club-shaped structures were found in infected fish. This suggests mortality of young tilapia may arise from decreased gill function in response to Cryptobia infestation.     

Retrospective eDNA assessment of potentially harmful algae in historical ship ballast tank and marine port sediments

Microalgal bloom events can cause major ecosystem disturbances, devastate local marine economies, and endanger public health. Therefore, detecting and monitoring harmful microalgal taxa is essential to ensure effective risk management in waterways used for fisheries, aquaculture, recreational activity, and shipping. To fully understand the current status and future direction of algal bloom distributions, we need to know how populations and ecosystems have changed over time. This baseline knowledge is critical for predicting ecosystem responses to future anthropogenic change and will assist in the future management of coastal ecosystems. We explore a NGS metabarcoding approach to rapidly identify potentially harmful microalgal taxa in 63 historic and modern Australian marine port and ballast tank sediment samples. The results provide a record of past microalgal distribution and important baseline data that can be used to assess the efficacy of shipping guidelines, nutrient pollution mitigation, and predict the impact of climate change. Critically, eDNA surveys of archived sediments were able to detect harmful algal taxa that do not produce microscopic fossils, such as Chattonella, Heterosigma, Karlodinium, and Noctiluca. Our data suggest a potential increase in Australian harmful microalgal taxa over the past 30 years, and confirm ship ballast tanks as key dispersal vectors. These molecular mapping tools will assist in the creation of policies aimed at reducing the global increase and spread of harmful algal taxa and help prevent economic and public‐health problems caused by harmful algal blooms.     

Physiological seawater adaptation in juvenile Atlantic salmon (Salmo salar) autumn migrants

Summary

• 1 About 25 % of juvenile Atlantic salmon (Salmo salar) migrating downstream in the River Frome in southern England do so in the autumn rather than in the spring. Here, we examine the physiological status of these fish with regard to those features that adapt them to sea water during the parr–smolt transformation (i.e. gill Na⁺K⁺ ATPase activity; the number, size and type of chloride cells on the gill lamellae; salinity tolerance and relative plasma thyroid levels).
• 2 Autumn migrants, and those fish which subsequently reside in the tidal reaches during the winter, are not sufficiently physiologically adapted to permit permanent or early, entry into the marine environment.
• 3 It is not known what proportion of autumn migrating fish survive and return to spawn as adults. If significant numbers do return, however, the production from tidal reach habitats must be taken into account in the development of salmon stock management strategies, especially monitoring and assessment programmes, and in the evaluation of factors affecting stocks.

     

A Systematic Review of Changes in Marine Mammal Health in North America, 1972-2012: The Need for a Novel Integrated Approach

Marine mammals are often cited as “sentinels of ocean health” yet accessible, synthesized data on their health changes that could effectively warn of ocean health changes are rare. The objectives of this study were to 1) perform a systematic review of published cases of marine mammal disease to determine spatial and temporal trends in disease from 1972–2012, including changes in regions and taxa affected and specific causes; and 2) compare numbers of published cases of neoplasia with known, hospital-based neoplasia records to explore the causes of discrepancy between numbers of published cases and true disease trends. Peer-reviewed literature was compiled, and data were collected from The Marine Mammal Center database in Sausalito, California for comparison of numbers of neoplasia cases. Toxicoses from harmful algal blooms appear to be increasing. Viral epidemics are most common along the Atlantic U.S. coastline, while bacterial epidemics, especially leptospirosis, are most common along the Pacific coast. Certain protozoal and fungal zoonoses appear to be emerging, such as Toxoplasma gondii in southern sea otters in California, and Cryptococcus gattii in cetaceans in the Pacific Northwest. Disease reports were most common from California where pinniped populations are large, but increased effort also occurs. Anthropogenic trauma remains a large threat to marine mammal health, through direct mortality and indirect chronic disease. Neoplasia cases were under-reported from 2003–2012 when compared to true number of cases, and over-reported in several years due to case duplication. Peer-reviewed literature greatly underestimates the true magnitude of disease in marine mammals as it focuses on novel findings, fails to reflect etiology of multifactorial diseases, rarely reports prevalence rather than simple numbers of cases, and is typically presented years after a disease first occurs. Thus literature cannot guide management actions adequately, nor inform indices of ocean health. A real-time, nationally centralized system for reporting marine mammal disease data is needed to be able to understand how marine mammal diseases are changing with ecosystem changes, and before these animals can truly be considered ‘sentinels of ocean health’.