Cyanobacterial diversity held in microbial biological resource centers as a biotechnological asset: the case study of the newly established LEGE culture collection

Cyanobacteria are a well-known source of bioproducts which renders culturable strains a valuable resource for biotechnology purposes. We describe here the establishment of a cyanobacterial culture collection (CC) and present the first version of the strain catalog and its online database (http://lege.ciimar.up.pt/). The LEGE CC holds 386 strains, mainly collected in coastal (48%), estuarine (11%), and fresh (34%) water bodies, for the most part from Portugal (84%). By following the most recent taxonomic classification, LEGE CC strains were classified into at least 46 genera from six orders (41% belong to the Synechococcales), several of them are unique among the phylogenetic diversity of the cyanobacteria. For all strains, primary data were obtained and secondary data were surveyed and reviewed, which can be reached through the strain sheets either in the catalog or in the online database. An overview on the notable biodiversity of LEGE CC strains is showcased, including a searchable phylogenetic tree and images for all strains. With this work, 80% of the LEGE CC strains have now their 16S rRNA gene sequences deposited in GenBank. Also, based in primary data, it is demonstrated that several LEGE CC strains are a promising source of extracellular polymeric substances (EPS). Through a review of previously published data, it is exposed that LEGE CC strains have the potential or actual capacity to produce a variety of biotechnologically interesting compounds, including common cyanotoxins or unprecedented bioactive molecules. Phylogenetic diversity of LEGE CC strains does not entirely reflect chemodiversity. Further bioprospecting should, therefore, account for strain specificity of the valuable cyanobacterial holdings of LEGE CC.

Histological alterations in the structure of the testis in tench (Tinca tinca) after exposure to 17 alpha-ethynylestradiol

Environmental pollution with synthetic estrogens may pose a serious threat to reproduction of aquatic wildlife species. The current study describes the effects of 17α-ethynylestradiol (EE2 ) on the structure of the testis in tench (Tinca tinca). Adult male tench were exposed to sublethal doses of EE2 (50, 100, and 500 μg/Kg t.w.) under semistatic conditions for a period of 30 days. The condition factor (CF), testicular somatic index (TSI), and histology (including a morphometric analysis) of the testis were examined. No consistent differences were observed in the CF of EE2 -exposed tench when compared with nonexposed fish. A significant decrease in TSI could only be observed at a 50 μg/Kg t.w. EE2 dose (p < 0.05) when compared with the control group. The histopathology of the testis was associated with loss of normal tubular structure with increased doses of exposure, decrease of tubule number, degeneration in Sertoli and Leydig cells, increase in necrotic testicular cells including formation of syncytia structures and, finally, a high incidence of fish with early primary oocytes at 100 and 500 μg/Kg t.w. EE2 . These results indicate that long-term exposure to EE2 may produce clear negative effects on testicular structure in tench.

Production of anatoxin-a by cyanobacterial strains isolated from Portuguese fresh water systems

The occurrence of anatoxin-a in several freshwater systems in Portugal and its production by Portuguese cyanobacterial strains, after cultivation in laboratory, were studied. Surface water samples from 9 water bodies, for recreational and human consumption usage, were surveyed for anatoxin-a presence and for obtaining cultures of pure cyanobacterial strains. Anatoxin-a analysis was performed by high performance liquid chromatography (HPLC) with fluorescence detection (FLD) followed by Mass Spectrometry (MS) confirmation. No anatoxin-a was detected in all the natural water samples (limit of detection (LOD) = 25 ng l(-1)) but among the 22 isolated cyanobacterial strains, 13 could produce anatoxin-a in laboratory conditions (LOD = 3 ng g(-1) dw). This proportion of anatoxin-a producing strains (59.1%) in laboratory is discussed considering the hypothesis that anatoxin-a is a more frequent metabolite in cyanobacteria than it was thought before and making its occurrence in Portuguese freshwaters almost certain. Therefore, health and ecological risks caused by anatoxin-a in Portugal, should be seriously considered.

Effects of cyanobacterial extracts containing anatoxin-a and of pure anatoxin-a on early developmental stages of carp

This study compares the effects of pure anatoxin-a and cyanobacterial extracts of an anatoxin-a producing strain on early stages of development of carp. Carp eggs were exposed from 2:30 h to 4 days post-fertilization to different ecologically relevant concentrations of anatoxin-a, provided as pure toxin or contained in the cyanobacterial extracts. Data on time to mortality, mortality rate, time to hatching, hatching rate, skeletal malformations rate, and larval standard length were registered until 8 days post-fertilization. At any tested concentration of anatoxin-a, the pure toxin was almost harmless to carp early stages of development, contrarily to cell extracts that were highly toxic. Only an adverse effect on the larval length was found at the highest concentration of pure toxin, while increasing concentrations of cell extracts caused increasing adverse effects in all the analyzed parameters. Anatoxin-a producing cyanobacteria should be regarded as putative modulators of aquatic ecosystems communities.

Uptake and depuration of anatoxin-a by the mussel Mytilus galloprovincialis (Lamarck, 1819) under laboratory conditions

Cyanobacterial blooms tend to be more common in warm and nutrient-enriched waters and are increasing in many aquatic water bodies due to eutrophication. The aim of this work is to study the accumulation and depuration of anatoxin-a by Mytilus galloprovincialis a widespread distributed mussel living in estuarine and coastal waters and recognized worldwide as a bioindicator (e.g. Mussel Watch programs). Research on the distribution and biological effects of anatoxin-a in M. galloprovincialis is important. Nevertheless, the risk of human intoxication due to the consumption of contaminated bivalves should also be considered. A toxic bloom was simulated in an aquarium with 5 x 10(5) cell ml(-1) of Anabaena sp. (ANA 37), an anatoxin-a producing strain. Mussels were exposed to Anabaena for 15 days and then 15 days of depuration followed. Three or more animals were sampled every 24h for total toxin quantification and distribution in soft tissues (edible parts). Water samples were also taken every 24h in order to calculate total dissolved and particulate anatoxin-a concentrations. Anatoxin-a was quantified by HPLC with fluorescence detection. No deaths occurred during accumulation and depuration periods. One day after the beginning of depuration, the toxin could not be detected in the animals. Anatoxin-a is distributed in the digestive tract, muscles and foot and is probably actively detoxified.

Toxicology and detection methods of the alkaloid neurotoxin produced by cyanobacteria, anatoxin-a

Freshwater resources are under stress due to naturally occurring conditions and human impacts. One of the consequences is the proliferation of cyanobacteria, microphytoplankton organisms that are capable to produce toxins called cyanotoxins. Anatoxin-a is one of the main cyanotoxins. It is a very potent neurotoxin that was already responsible for some animal fatalities. In this review we endeavor to divulgate much of the internationally published information about toxicology, occurrence and detection methods of anatoxin-a. Cyanobacteria generalities, anatoxin-a occurrence and production as well as anatoxin-a toxicology and its methods of detection are the aspects focused in this review. Remediation of anatoxin-a occurrence will be addressed with a public health perspective. Final remarks call the attention for some important gaps in the knowledge about this neurotoxin and its implication to public health. Alterations of aquatic ecosystems caused by anatoxin-a is also addressed. Although anatoxin-a is not the more frequent cyanotoxin worldwide, it has to be regarded as a health risk that can be fatal to terrestrial and aquatic organisms because of its high toxicity.

Analysis of anatoxin-a in biological samples using liquid chromatography with fluorescence detection after solid phase extraction and solid phase microextraction

Anatoxin-a is a naturally occurring, potent neurotoxin produced by some species of cyanobacteria in freshwaters. This toxin, which is a potential health hazard, especially to animals, has been determined in different biological matrices such as several cyanobacterial cultures and water samples and carps and mussels tissue using a sensitive High Performance Liquid Chromatography with Fluorescence detection method. Sonication was the technique selected for the extraction of intracellular anatoxin-a and solid phase extraction using weak cation exchange was used for the concentration and purification of the samples. 4-Fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was used to convert anatoxin into a highly fluorescent derivative. Recovery experiments were performed for each type of matrix used in this work, and adequate values were obtained (71-87%). Limits of detection for anatoxin-a were estimated to be in the ng/L and ng/g level for water and cyanobacterial samples, respectively. The results obtained were also compared with those obtained after using solid phase microextraction, as an alternative for the extraction and purification of the samples. Advantages and disadvantages regarding to the efficiency for impurities removal, simplicity and rapidity and the potential for concentration enhancement of using both methodologies have been also discussed.

Acute effects of an anatoxin-a producing cyanobacterium on juvenile fish—Cyprinus carpio L

The worldwide increase of eutrophication in fresh water bodies has caused cyanobacterial blooms to be more frequent. Anatoxin-a is a potent neurotoxin known to be produced by several genera of cyanobacteria including Anabaena. In this work, we exposed juvenile carps to freeze-dried cells of a toxic strain of the cyanobacterium Anabaena sp. during a 4-day period. Two different cell density--10(5) and 10(7) cell ml(-1)--were assayed. Lethality and anatoxin-a concentration in the whole fish were determined. In the higher cell density, all fish died between 26 and 29 h after exposure to toxin, whereas in the 10(5) cell ml(-1) density no deaths were observed. Levels of anatoxin-a in the whole fish ranged between 0.031 microg g(-1)d.w. at the 10(5) cell ml(-1) concentration and 0.768 microg g(-1)d.w. at 10(7) cell ml(-1). Minor uptake of anatoxin-a occurred.

[Results of regular follow-up after removal of colorectal adenomas]

After resection of colorectal adenoma 453 patients were included in a follow-up program between 1. 1. 1980 and 30. 6. 1991. 275 patients underwent regular follow-up examinations, the primary drop-out rate was 39.2%. In the 275 participating patients 492 primary adenoma were removed. 174 patients (63.3%) had a single adenoma, while 101 patients showed multiple primary adenoma (36.7%). The average follow-up interval was 37 (+/- 28.2) months. During follow-up we found new adenoma in 105 patients (38.2%), the Kaplan-Meier estimation of the five-year-recurrence rate was 55.9% (95% confidence-interval 46.9 to 64.8%). The risk of recurrence was increased in patients with multiple primary adenoma (p = 0.003) and multivariate risk analysis showed an independent influence of histology on recurrence rate (p = 0.07). In six patients colorectal carcinoma were detected during adenoma follow-up. During regular follow-up examinations after surgical treatment for colorectal adenoma in more than 30% of all patients new colorectal polyps were detected and removed. Therefore follow-up for colorectal adenoma is effective in prevention of colorectal carcinoma. Still frequency of follow-up examinations have to be adapted to the individual risk of recurrence for each patient.

[Follow-up in stomach carcinoma]

For ten years after resection of stomach cancer patients were routinely examined to detect early asymptomatic recurrence, 96 records were analyzed, 21 patients with recurrence of cancer were found--3 local recurrence and 18 distant metastases. There was no anastomosis recurrence, 20 of these patients had clinical symptoms. About 90 percent of all recurrences were found in the first two years. After diagnosis of recurrence the one-year-survival-rate was only eight percent. We believe that the regular follow-up following resection of stomach cancer is not an effective method of detections asymptomatic curable recurrence. For this reason we recommend intensifying individual care and decreasing endoscopic or radiological examinations.

[Individual risk-related after-care in colorectal cancer?]

Efficacy of the regular follow-up program and influence on survival rate following treatment of recurrence were evaluated. 556 follow-up records of patients after resection of colorectal cancer were analysed. The primary drop-out rate was 12.4%. Recurrences were found in 26.6% (n = 128). 53.1% of recurrences were symptomatic at diagnosis of recurrence. Curative resection of recurrence was only performed in 19.5%. 46.1% were given palliative and 34.4 no specific oncologic treatment. We define efficacy as the rate of curative asymptomatic recurrence. This was 3.5% of all patients. From the curative resection of recurrence only 6 patients were free of recurrence longer than 2 years. No second resection of recurrence was possible. Different treatment of recurrence did influence the survival rate (p = 0.09). There was no difference in prognosis for asymptomatic and symptomatic recurrences (p greater than 0.8). In order to increase the efficacy of follow-up for colorectal cancer we are introducing a new concept based on individual risk factors.

[Routine gastroscopy before cholecystectomy]

We are of the opinion that the investigation of the upper gastrointestinal tract must precede an elective cholecystectomy. In a prospective study the value of preoperative oesophagogastroduodenoscopy preceding elective cholecystectomy is considered. 589 gastroscopies were performed in our endoscopy unit on 960 patients coming to elective gallbladder surgery. Only in 56% of patients we detected no abnormalities. Our plan of therapy was changed in 113 patients (11.7%). 11 patients were discharged after conservative medical therapy (1.1%), in 31 cases simultaneous procedures were performed (3.2%). After additional medical treatment 71 patients came to elective cholecystectomy (7.4%).

[Rupture of a hydatid cyst of the liver into the bile ducts evaluated by computerized tomography (author's transl)]

Case report of an cysto-biliary fistula in hydatid disease of the liver evaluated by computed tomography and endoscopic retrograde cholangiography.