Plankton community structure and size spectra in the Georgian Bay and North Channel ecosystems

Patterns in the size distribution and taxonomic composition of phytoplankton and zooplankton communities for 1974 in Georgian Bay and the North Channel are described. The Diatomeae predominate the phytoplankton in both areas. Copepods, particularly Calanoida, comprise the greatest fraction of the zooplankton biomass. Normalized plankton biomass spectra for both ecosystems are typical of those found in Lake Superior and offshore Lake Huron. The plankton communities of Georgian Bay and the North Channel are thus similar to the most oligotrophic of the Laurentian Great Lakes.     

Exploring aquatic ecosystem health: a multi-trophic and an ecosystemic approach

The field of aquatic ecosystem health is a new and developing discipline. The restoration and recovery of habitats is extremely complex and requires a clear understanding of a desirable and maximum/minimum set of conditions which is acceptable, achievable, and cost-effective for implementation. Since this field of research is still in its infancy, the technology for an integrative and innovative assessment will require a combination of physical, chemical, and biological methods and researchers will have to adopt and use some of the routine chemical, limnological, physiological, ecological, and toxicological procedures. A multi-disciplinary, multi-trophic and an ecosystemic approach has been initiated and applied in the North American Great Lakes during the past several years. This strategy, consisting of structural and functional indicators and endpoints, was implemented in the Great Lakes Areas of Concern adopting a field to laboratory approach for a holistic and integrated evaluation of the ecosystem. Some examples from our Great Lakes experience are presented. The ecosystem health technology should look beyond the traditional approach and must develop innovative, sensitive, automated, and cost-effective procedures including computer-assisted techniques to deal with the problems of stress, healing, recovery, and remediation.     

A sensitive screening bioassay technique for the toxicological assessment of small quantities of contaminated bottom or suspended sediments

Biological impact assessment of sediment-bound contaminants is currently considered essential in addition to routine chemical characterization. Conventional methods of sediment bioassessment require relatively large quantities of the sample. When sample sizes are limited however, these methods become ineffective. To overcome this problem, the Limited Sample Bioassay (LSB) technique was developed. Bioassays conducted with bottom sediments and suspended particulates from western, central and Arctic regions of Canada indicated that the newly developed LSB technique successfully evaluated the contaminant/nutrient impact on laboratory-grown cultures of algae. The LSB method produced results which were comparable to those from standard elutriate bioassays conducted with natural phytoplankton size assemblages. The data suggest that the LSB can play an important role in providing a quick, simple, sensitive, and inexpensive screening technique for assessing the bioavailability of contaminants (or nutrients) from sediment of limited quantity.     

Assessing the impact of sewage effluent on the ecosystem health of the Toronto Waterfront (Ashbridges Bay), Lake Ontario

The ecosystem health of the Toronto Waterfront (Ashbridges Bay), Lake Ontario which receives treated sewage effluent was investigated during 1987 and 1988 by means of a functional and structural battery of tests. The functional tests included in situ size-fractionated primary productivity, Algal Fractionation Bioassays (AFBs), unfiltered and filtered bioassays, and sediment assays with Daphnia magna and Hyalella azteca. The structural evaluation involved the biomonitoring of the components of the microbial loop, such as bacteria, autotrophic picoplankton, heterotrophic nanoflagellates, and protozoa. The experimental results reveal a diversity of physiological responses to the complex nutrient and contaminant regimes by the indigenous phytoplankton. There was no evidence of the impact of chlorination on the primary productivity of the Bay. The overall productivity was higher during the post-chlorination period than the pre-chlorination phase. The high rates of microplankton + netplankton productivity near the outfall have been attributed to the bioavailability of nutrients which, quite possibly, exert ameliorating effects on metal toxicity. In contrast, the low ultraplankton rates have been interpreted to be due to their well-known sensitivity to contaminants. The Effluent Receiving Water Bioassays (ERWB) with filtered and unfiltered experiments provided interesting insight and appear to be a potentially useful assessment tool. Generally, the unfiltered water compared to the filtered was toxic to the offshore test phytoplankton. This demonstrates a unique ecological adaptation to the prevailing in situ conditions by the Bay community which might be important from the restoration point of view. However, the offshore population was found to be sensitive to the particulate-bound toxicity as indicated by the unfiltered bioassays. Consequently, it is essential to probe the complexity of nutrient-contaminant interactions which ultimately appear to determine the toxicity and the resulting health of the biota. Furthermore, our experiments have shown that the particulate-matter is an important carrier of both nutrients and contaminants in Ashbridges Bay. The sediment bioassays for Station 419 indicated that sediments were toxic during both the pre- and post-chlorination phases. Both solid and liquid phase testing indicated toxicity of sediment to the acute Daphnia test. The Hyalella chronic assay showed good survival during the 4-wk period of the experiment, in contrast to the toxicity observed for phytoplankton and Daphnia. This may be due to large mounts of organic matter available in the Bay. The invertebrate bioassays confirmed the lack of impact of chlorination. Finally, the microbial loop seems to be a sensitive, rapid, and an early warning bioindicator of anthropogenic stress. The multi-trophic battery of structural and functional strategy adopted in our laboratory appear to be holistic and effective. The strategy has a considerable potential for developing eco-technology for a badly needed assessment and restoration of ecosystem health of the Great Lakes as well as other perturbed environments in the world.     

Serological Cross-Reaction Between O-Antigens of Shigella dysenteriae Type 4 and an Environmental Escherichia albertii Isolate

An environmental freshwater bacterial isolate, DM104, appearing as Shigella-like colonies on selective agar plates was found to show strong and specific serological cross-reactivity with Shigella dysenteriae type 4. Biochemical identification according to the analytical profile index, molecular serotyping by restriction of the amplified O-antigen gene cluster (rfb-RFLP), together with phylogenetic analysis of the 16S rRNA gene and multi-locus sequence analysis, identified the isolate as Escherichia albertii. rfb-RFLP of DM104, revealed a profile different from that of S. dysenteriae type 4. However, western blot analysis of extracted lipopolysaccharides demonstrated strong cross-reactivity with S. dysenteriae type 4 using specific monovalent antisera and a lipopolysaccharide gel banding profile similar to that of S. dysenteriae type 4. The observed O-antigen cross-reaction between an E. albertii isolate and S. dysenteriae extends our knowledge of the extent of O-antigen cross-reaction within the Escherichia/Shigella group of organisms, and offers the possibility of using DM104 and similar cross-reacting strains as shigellosis vaccine candidates.     

Prospects for robust biocatalysis: engineering of novel specificity in a halophilic amino acid dehydrogenase

Heat- and solvent-tolerant enzymes from halophiles, potentially important industrially, offer a robust framework for protein engineering, but few solved halophilic structures exist to guide this. Homology modelling has guided mutations in glutamate dehydrogenase (GDH) from Halobacterium salinarum to emulate conversion of a mesophilic GDH to a methionine dehydrogenase. Replacement of K89, A163 and S367 by leucine, glycine and alanine converted halophilic GDH into a dehydrogenase accepting l-methionine, l-norleucine and l-norvaline as substrates. Over-expression in the halophilic expression host Haloferax volcanii and three-step purification gave ~98 % pure protein exhibiting maximum activity at pH 10. This enzyme also showed enhanced thermostability and organic solvent tolerance even at 70 °C, offering a biocatalyst resistant to harsh industrial environments. To our knowledge, this is the first reported amino acid specificity change engineered in a halophilic enzyme, encouraging use of mesophilic models to guide engineering of novel halophilic biocatalysts for industrial application. Calibrated gel filtration experiments show that both the mutant and the wild-type enzyme are stable hexamers.     

A preliminary study of vertical movement of Eudorina elegans and trinema lineare during a bloom caused by them

Summary The paper describes a polluted pond from India, which exhibited a well marked thermal stratification in summer. The surface and bottom strata of water exhibited a temperature difference of 8° C. The paper also describes the diurnal movement of Eudorina elegans and Trinema lineare which formed a bloom in the pond. The movements of these organisms are interpreted on the basis of fluctuations in temperature and light conditions. The possibility of the competition for space is also discussed.

---

Sommaire On a décrit un cas de stratification thermale bien marquée dans un étang pollué en dépit de peu de profondeur de son bassin, dans un été en Inde. Les couches superficielles et de fond de l'eau ont montré une différence de temperature de 8° C. On décrit également le mouvement diurnal d'Eudorina elegans et Trinema lineare qui ont formé une floraison dans l'étang. Le déplacement de ces organismes est interprété en fonction du changement de temperature et de la luminosité. La possibilité d'une concurrence pour l'espace est discutée.

---

---

Hydrobiological Laboratory, Department of Botany, Osmania University, Hyderabad-7 (A.P.), India.     

Preface

Aquatic Ecosystem Health and Management Society     

Association of Angiotensin-Converting Enzyme gene polymorphism in Pakistani women with the atypical steroidogenesis in Polycystic ovarian syndrome: A case-control study

BackgroundPolymorphism in the angiotensin-converting enzyme gene (ACE) is responsible for elevated ACE concentrations in plasma. High ACE levels induce insulin resistance and hyperandrogenism, which are the main attributes of polycystic ovary syndrome (PCOS). Therefore, it was hypothesized that I/D polymorphism plays a role in the pathogenesis of PCOS.ObjectiveA case-control study was designed to investigate the association of I/D polymorphism of the ACE gene with PCOS in Pakistani women of reproductive age.MethodsACE I/D polymorphism was assessed in 252 women of age group 16–40 years. For genotypic analysis, PCR amplification of genomic DNA was carried out. Statistical analysis was performed to interpret the results using SPSS software.ResultsOur study showed that PCOS women were more likely to have a high body mass index and waist circumferences. Most PCOS patients had menstrual irregularities 99.3%, hirsutism 75.2% and cysts in ovaries 66.6%, along with other hyperandrogenic conditions (P-value = 0.001). The genotypic and allelic frequencies were significantly different between patients and controls. There was a significant association of three genotypes with the ratio of LH: FSH among PCOS patients (P = 0.05). Anthropometric characters, comorbidities, clinical symptoms, and PCOS conditions showed no statistical significance with ACE polymorphism.ConclusionsACE I/D polymorphism was not found associated with clinical conditions of PCOS in women of reproductive age. However, it was associated with atypical steroidogenesis. So, it indicates that ACE I/D polymorphism aggravates the pathogenesis of PCOS.