Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers

Abstract Background Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species. Results We found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments). Conclusions The results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment

Genes Associated with 2-Methylisoborneol Biosynthesis in Cyanobacteria: Isolation, Characterization, and Expression in Response to Light

The volatile microbial metabolite 2-methylisoborneol (2-MIB) is a root cause of taste and odor issues in freshwater. Although current evidence suggests that 2-MIB is not toxic, this compound degrades water quality and presents problems for water treatment. To address these issues, cyanobacteria and actinomycetes, the major producers of 2-MIB, have been investigated extensively. In this study, two 2-MIB producing strains, coded as Pseudanabaena sp. and Planktothricoids raciborskii, were used in order to elucidate the genetic background, light regulation, and biochemical mechanisms of 2-MIB biosynthesis in cyanobacteria. Genome walking and PCR methods revealed that two adjacent genes, SAM-dependent methyltransferanse gene and monoterpene cyclase gene, are responsible for GPP methylation and subsequent cyclization to 2-MIB in cyanobacteria. These two genes are located in between two homologous cyclic nucleotide-binding protein genes that may be members of the Crp-Fnr regulator family. Together, this sequence of genes forms a putative operon. The synthesis of 2-MIB is similar in cyanobacteria and actinomycetes. Comparison of the gene arrangement and functional sites between cyanobacteria and other organisms revealed that gene recombination and gene transfer probably occurred during the evolution of 2-MIB-associated genes. All the microorganisms examined have a common origin of 2-MIB biosynthesis capacity, but cyanobacteria represent a unique evolutionary lineage. Gene expression analysis suggested that light is a crucial, but not the only, active regulatory factor for the transcription of 2-MIB synthesis genes. This light-regulated process is immediate and transient. This study is the first to identify the genetic background and evolution of 2-MIB biosynthesis in cyanobacteria, thus enhancing current knowledge on 2-MIB contamination of freshwater

Evidence for a Novel Marine Harmful Algal Bloom: Cyanotoxin (Microcystin) Transfer from Land to Sea Otters

“Super-blooms” of cyanobacteria that produce potent and environmentally persistent biotoxins (microcystins) are an emerging global health issue in freshwater habitats. Monitoring of the marine environment for secondary impacts has been minimal, although microcystin-contaminated freshwater is known to be entering marine ecosystems. Here we confirm deaths of marine mammals from microcystin intoxication and provide evidence implicating land-sea flow with trophic transfer through marine invertebrates as the most likely route of exposure. This hypothesis was evaluated through environmental detection of potential freshwater and marine microcystin sources, sea otter necropsy with biochemical analysis of tissues and evaluation of bioaccumulation of freshwater microcystins by marine invertebrates. Ocean discharge of freshwater microcystins was confirmed for three nutrient-impaired rivers flowing into the Monterey Bay National Marine Sanctuary, and microcystin concentrations up to 2,900 ppm (2.9 million ppb) were detected in a freshwater lake and downstream tributaries to within 1 km of the ocean. Deaths of 21 southern sea otters, a federally listed threatened species, were linked to microcystin intoxication. Finally, farmed and free-living marine clams, mussels and oysters of species that are often consumed by sea otters and humans exhibited significant biomagnification (to 107 times ambient water levels) and slow depuration of freshwater cyanotoxins, suggesting a potentially serious environmental and public health threat that extends from the lowest trophic levels of nutrient-impaired freshwater habitat to apex marine predators. Microcystin-poisoned sea otters were commonly recovered near river mouths and harbors and contaminated marine bivalves were implicated as the most likely source of this potent hepatotoxin for wild otters. This is the first report of deaths of marine mammals due to cyanotoxins and confirms the existence of a novel class of marine “harmful algal bloom” in the Pacific coastal environment; that of hepatotoxic shellfish poisoning (HSP), suggesting that animals and humans are at risk from microcystin poisoning when consuming shellfish harvested at the land-sea interface

Demographic, clinical and antibody characteristics of patients with digital ulcers in systemic sclerosis: data from the DUO Registry

OBJECTIVES: The Digital Ulcers Outcome (DUO) Registry was designed to describe the clinical and antibody characteristics, disease course and outcomes of patients with digital ulcers associated with systemic sclerosis (SSc). METHODS: The DUO Registry is a European, prospective, multicentre, observational, registry of SSc patients with ongoing digital ulcer disease, irrespective of treatment regimen. Data collected included demographics, SSc duration, SSc subset, internal organ manifestations, autoantibodies, previous and ongoing interventions and complications related to digital ulcers. RESULTS: Up to 19 November 2010 a total of 2439 patients had enrolled into the registry. Most were classified as either limited cutaneous SSc (lcSSc; 52.2%) or diffuse cutaneous SSc (dcSSc; 36.9%). Digital ulcers developed earlier in patients with dcSSc compared with lcSSc. Almost all patients (95.7%) tested positive for antinuclear antibodies, 45.2% for anti-scleroderma-70 and 43.6% for anticentromere antibodies (ACA). The first digital ulcer in the anti-scleroderma-70-positive patient cohort occurred approximately 5 years earlier than the ACA-positive patient group. CONCLUSIONS: This study provides data from a large cohort of SSc patients with a history of digital ulcers. The early occurrence and high frequency of digital ulcer complications are especially seen in patients with dcSSc and/or anti-scleroderma-70 antibodies

Effects of land management practices on water quality in Mississippi Delta oxbow lakes: Biochemical and microbiological aspects

The Mississippi Delta Management Systems Evaluation Area (MSEA) project was designed to assess the effects of land management practices on water quality in three small oxbow lake watersheds; Thighman (1338. ha, 16. ha lake); Beasley (915. ha, 25. ha lake); and Deep Hollow (132. ha, 8. ha lake). Monthly water samples were monitored for enzymatic activity (fluorescein diacetate hydrolysis, alkaline phosphatase, and substrate utilization), chemical and physical analysis (suspended solids, dissolved organic carbon, pH, nitrate, ammonium, orthophosphate, and electrical conductivity), phytoplankton and bacterioplankton populations. All of these parameters were influenced by the intrinsic nature of the watersheds, with some parameters shifting as management changes were imposed on the surrounding agricultural fields. Thighman lake water typically maintained the highest suspended solid levels, dissolved organic carbon, algal and bacterial populations, enzyme activities, and heterotrophic metabolic indexes. Introduction of reduced tillage practices and glyphosate-resistant crops in Beasley watershed resulted in lower levels of suspended sediments, but had minimal impact on overall ranking of biochemical or microbiological properties. Likewise, conversion of Deep Hollow watershed from reduced tillage to conventional tillage had little effect on suspended sediment, and most microbial activity parameters remained intermediate. However, canonical analysis indicated dynamic changes in the microbial community, suggesting that biological parameters of lake water quality were affected by changes in crop and soil management practices. © 2010

Gas Chromatographic Mass Spectrometry Determination of Geosmin and 2-methylisoborneol Off-Flavor in Mugil cephalus Roe

Botargo is the product of the industrial management of fresh roe of the grey mullet (Mugil cephalus). This food product is actually obtained from wild fish caught in different marine areas around the word. The increasing commercial demand of botargo has brought to carry out different fishing systems, gathering the wild mullet in restricted areas, lagoons, to be caught if necessary. This operating mode has caused the appearance of new problems related to the organoleptic approval by the consumers of fish and derived products, following off-flavor contamination derived from different microorganisms present in the lagoons. The most important off-flavor compounds are represented by 2-methylisoborneol (2-MIB) and geosmin (GSM) which give a muddy/musty smell and flavor to the fish. A simple and easy-to-use GC/MS method for the determination of 2-MIB and GSM has been developed. The method has been validated with the following parameters: instrument limit of detection (LOD) and of quantification (LOQ), precision, recovery, and linearity. The method carried out showed good LOD of 1.0 μg/kg and LOQ 2.0 and 5.0 μg/kg for GSM and 2-MIB, respectively. Validation parameters were in close agreement with those reported in the EC SANCO/12571/2013. Recoveries ranged from 80.2 to 121.4 %, with percent relative standard deviation (RSD%) ranging from 0.6 to 18.6 % in the most unfavorable case. Real sample analysis showed the presence of residues of both off-flavor in all botargo samples analyzed, except for sample S0, while in fresh roe samples, only S7 showed important residues of 2-MIB