Control of fermenters – a review

Fermenter control has been an active area of research and has attracted more attention in recent years. This is due to the new developments in other related areas which can be exploited to overcome the inherent difficulties in fermenter control. Beginning with conventional regulatory control of operating variables such as temperature, pH and dissolved oxygen concentration, research in fermenter control has undergone significant changes including the recent neural network based approaches. The objective of the paper is to focus the attention of the researchers to the developments in the control of batch, fed-batch and continuous fermenters over the past few years.     

Potential markers of preeclampsia – a review

Preeclampsia is a leading cause of maternal and fetal/neonatal mortality and morbidity worldwide. The early identification of patients with an increased risk for preeclampsia is therefore one of the most important goals in obstetrics. The availability of highly sensitive and specific physiologic and biochemical markers would allow not only the detection of patients at risk but also permit a close surveillance, an exact diagnosis, timely intervention (e.g. lung maturation), as well as simplified recruitment for future studies looking at therapeutic medications and additional prospective markers. Today, several markers may offer the potential to be used, most likely in a combinatory analysis, as predictors or diagnostic tools. We present here the current knowledge on the biology of preeclampsia and review several biochemical markers which may be used to monitor preeclampsia in a future, that, we hope, is not to distant from today.     

Cryopreservation of eukaryotic algae – a review of methodologies

Since pioneering work in the early 1960s, there has been growing interest and numerous experimental investigations into the cryopreservation of algal material. Mostly, these studies relate to the requirement for long term preservation and storage of algal material contained in culture collections or used in the seaweed mariculture industry. The present review deals with techniques used in the cryopreservation of biological samples and their application to both micro- and macroalgae. Methods for the prevention of cell damage and freezing injury during the cooling and low-temperature storage of algal material are discussed with reference to the effect on viability of such variables as cooling rates, final temperatures attained, the use of various types and concentrations of cryoprotectants, thawing rates, and storage times and temperatures. Some consideration is also given to the various methods used for increasing cell viability, including the induction of freezing tolerance. Cryopreservation protocols employed by numerous workers in this field are detailed, and concluding remarks are made on those techniques and conditions providing optimum viability of cryopreserved algae. This revised version was published online in June 2006 with corrections to the Cover Date.     

Prochlorophyta – a matter of class distinctions

Prochloron (a marine symbiont) and Prochlorothrix (from freshwater plankton) contain chlorophylls a and b; Prochlorococcus (common in marine picoplankton) contains divinyl-chlorophylls a and b. Like cyanophytes they are all clearly photosynthetic prokaryotes, but since they contain no blue or red bilin pigment they were assigned to a new algal sub-class, the Prochlorophyta. However, since their possible phylogenetic relationships to ancestral green-plant chloroplasts have not received support from molecular biology, it now seems expedient to consider them as aberrant cyanophytes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Production of pectolytic enzymes – a review

Pectolytic enzymes play an important role in food processing industries and alcoholic beverage industries. These enzymes degrade pectin and reduce the viscosity of the solution so that it can be handled easily. These enzymes are mainly synthesized by plants and microorganisms. Aspergillus niger is used for industrial production of pectolytic enzymes. This fungus produces polygalacturonase, polymethylgalacturonase and pectinlyase. This review mainly concerns with the production of pectolytic enzymes using different carbon sources. It also deals with the effect of operating parameters such as temperature, aeration rate, agitation and type of fermentation on the production of these enzymes.     

Range-body mass interactions of a northern ungulate – a test of hypothesis

Summer diet, summer temperature, length of the growth season and animal density appeared to best explain annual and regional differences in calf and yearling body mass in moose from southeastern Norway. In general animals inhabiting steep, alpine landscapes had less body mass than animals using flat, low-altitude habitats. Autumn body mass of calves and yearlings decreased with increasing snow depth during the preceding winter and spring. However, calf body mass was more influenced by the summer range and less by the winter range than was body mass of yearlings. There was no indication that the effect of snow depth on autumn body mass was greater in moose living on poor than on good summer ranges. Body mass decreased with increasing competition for summer forage, while the winter range mainly had an density-independent effect. Habitat quality, expressed as regression lines between calf and yearling body mass and animal density (hunting yield), differed between regions. On ranges of medium and high altitude where birch (Betula spp.) rowan (Sorbus aucuparia) and bilberry (Vaccinium myrtillus) dominated moose summer diet, body mass decreased at a rapid rate with increasing animal density. Body mass decreased at a slower rate at low-altitude ranges and at high-altitude ranges where willow (Salix spp.) and forbs dominated the diet. Body mass of lactating cows decreased with increasing animal density, but animal density did not affect body mass of non-lactating cows. There was no indication that the decrease in autumn body mass with increasing moose density over the last 25 years has caused a decrease in animal condition (ability to survive the winter). The results are discussed in relation to the effect of summer and winter range on population regulation in moose. It is concluded that a density-dependent effect is apparent on the summer range even at low and intermediate population densities. On the winter range, on the other hand, density-dependence is likely to occur only at high levels of population density. Received: 4 February 1997 / Accepted: 1 February 1999     

Transdermal applications of ethosomes – a detailed review

Skin, the largest organ of the body serves as a potential route of drug delivery for local and systemic effects. However, the outermost layer of skin, the stratum corneum (SC) acts as a tough barrier that prevents penetration of hydrophilic and high molecular weight drugs. Ethosomes are a novel phospholipid vesicular carrier containing high ethanol concentrations and offer improved skin permeability and efficient bioavailability due to their structure and composition. This article gives a review of ethosomes including their compositions, types, mechanism of drug delivery, stability, and safety behaviour. This article also provides a detailed overview of drug delivery applications of ethosomes in various diseases.     

EIIaCre – Utility of a general deleter strain

Transgenic Research -     

The hydraulic architecture of Pinaceae – a review

We reviewed the literature to examine the vulnerability to water stress-induced embolism of Pinaceae relative to other conifers and to study the inter-relationships among the main traits involved in the hydraulic function within the Pinaceae. Results showed that Pinaceae (particularly the genus Pinus) are more vulnerable to xylem embolism, and show less variability in this character, than other conifers. Detailed data from 12 populations of Pinaceae (11 species) from three different areas (Piñol and Sala 2000; Martínez-Vilalta and Piñol 2002; Oliveras et al. 2003) was used to study the relationships among hydraulic properties of stems. These included: leaf-to-wood area ratio (A_L:A _W), wood- and leaf-specific hydraulic conductivity (K_W and K_L, respectively), vulnerability to xylem embolism (Ψ_50PLC), carbon isotope composition of needles (δ¹³C) and minimum needle water potential (minimum Ψ_L). Results showed that hydraulic properties tended to be more correlated among each other than with indicators of environmental (precipitation to potential evapotranspiration ratio, P/E) or physiological water stress (minimum Ψ_L). The only exception was an increase of δ¹³C with decreasing minimum Ψ_L and P/E. Overall, A_L:A _W ratio decreased with increasing vulnerability to xylem embolism, and with increasing K_W and K_L (P<0.05). We found a strong positive relationship between carbon isotope composition and the estimated maximum loss of conductivity due to xylem embolism under field conditions, suggesting stronger stomatal control in more vulnerable species with higher levels of native embolism. Overall, results are consistent with a range of drought-avoidance strategies to minimise the gradient of water potential through the xylem, and show that different relationships among traits are possible depending on the scale of study (individual vs. species or populations). The strong interdependence among hydraulic traits implies that no single trait is a sufficient predictor of drought-resistance in Pinaceae. Finally, it is hypothesised that the intrinsically vulnerable xylem of pines may limit their survival under extremely dry conditions.     

The promise of e-Health – a Canadian perspective

Canadians value their health care system above any other social program. Canada's system of health care faces significant financial and population pressures, relating to cost, access, quality, accountability, and the integration of information and communication technologies (ICTs). The health-system also faces certain unique challenges that include care delivery within a highly decentralised system of financing and accountability, and care delivery to a significant portion of the population sparsely distributed across a landmass of 10 million square kilometres, in areas of extreme climatic conditions. All of these challenges are significant catalysts in the development of technologies that aim to significantly mitigate or eliminate these selfsame challenges.The system is undergoing widespread review, nationally, and within each province and territory, where the bulk of care provision is financed and managed. The challenges are being addressed by national, regional and provincial initiatives in the public, private and not-for-profit sectors.The promise of e-Health lies in the manner and degree to which it can mitigate or resolve these challenges to the health system and build on advancements in ICTs supporting the development of a health infostructure. Canada is actively developing and implementing technological solutions to deliver health information and health care services across the country. These solutions, while exciting and promising, also present new challenges, particularly in regard to acceptable standards, choice of technologies, overcoming traditional jurisdictional boundaries, up-front investment, and privacy and confidentially.Many organisations and governments are working to address these challenges. The Canadian Institute for Health Information (CIHI) will play an increasingly significant role in these initiatives, as the management of health information becomes a more crucial factor in the successful delivery of health care services in the new millennium.     

Biocatalytic conversion of turpentine – a wood processing waste – into oxygenated monoterpenes

Abstract

Three kinds of turpentine (a waste by-product of industrial wood processing) of various monoterpene compositions were transformed by Picea abies cells and the product yields monitored in relation to the initial turpentine concentration. The major products obtained were trans-verbenol, trans-pinocarveol, myrtenol, α-terpineol, and p-cymen-8-ol depending on the substrate composition. The absolute quantitative values of the major products were evaluated for a substrate concentration of 0.86 g L^?1. The concentration of trans-verbenol and trans-pinocarveol after twelve days of biotransformation was 768 and 388 mg L^?1, respectively. The substrate was uptaken by Picea abies cells within the first three days and the majority of products released in five days. Although not all the starting material was consumed, the Picea abies suspension culture was able to convert concentrations of turpentine as high as 4.3 g L^?1 into valuable products. By precise selection of the substrate concentration and time course, favourable conversion to products could be achieved.     

Biomechanics of a branch – stem junction in softwood

Direct measurement of strain field in a mechanically loaded Norway spruce branch–stem junction was performed by means of electronic speckle pattern analysis. Results were compared with strain distribution in a polyester cast of identical shape as the branch–stem junction, and a simplified polyester model consisting of two half-cylinders. Compared to polyester models, the branch–stem junction was characterised by a very homogeneous distribution of strain, which can be interpreted as a homogeneous distribution of stress in terms of fraction of material strength. This optimised transfer of mechanical load from the branch to the stem is achieved by a combination of naturally optimised shape with, additionally, optimised mechanical wood properties in the junction area.     

Hydrobiology of the Cochin backwater system – a review

On the south west coast of India, there is an extensiveestuarine system of backwaters, of which Vembanad Lake is the largest. The backwaters of Kerala support as much biological productivity and diversity as tropical rain forests. They are responsible for the rich fisheries potential of Kerala. Cochin backwaters situated at the tip of the northern Vembanad lake is a tropical positive estuarine system extending between 9° 40 and 10° 12N and 76° 10' and 76° 30 E with its northern boundary at Azheekode and southern boundary at Thannirmukham bund. The lake has a length of 80 km and the width varies between 500 and 4000 m. A channel, about 450 m wide at Cochin gut and another at Azheekode, make permanent connections with the Arabian Sea. The depth of the estuary varies considerably. While the shipping channels are maintained at a depth of 10–13 m, the major portion of the estuary has a depth range of 2–7 m. Water from two major rivers viz., Periyar and Muvattupuzha drain into this estuary. During south west monsoon, the estuary is virtually converted into a freshwater basin even in areas around barmouth where salt water penetration occurs below 5 m depth only. The major hydrological variable in the Cochin backwaters is salinity, similar to the situations encountered in estuaries with a gradual declension of salinity from 30 at the entrance of the estuary to 0.2 at the point of entry of the rivers. Salinity gradient in the Cochin backwaters supports diverse species of flora and fauna depending on their capacity to tolerate oligohaline, mesohaline or marine conditions. Low lying swamps and tidal creeks, dominated by sparse patches of mangroves with their nutrient rich physical environment, support larvae and juveniles of many economically important species. Backwaters also act as nursery grounds of commercially important prawns and fishes. The fields around the backwater are suitable for aquaculture. These areas support traditional, seasonal and perennial prawn fishery. The changes in the hydrology controlled by the seasons play an important role in regulating the migrant fauna of the estuary. The Cochin backwater supports a well established endemic fauna. The nutrients and pollutants introduced into the estuary control to a great extent the distribution and abundance of less tolerant species in ecologically sensitive areas in the backwaters. Cochin backwaters, widely regarded as one of the polluted estuaries in India, receive contaminated freshwater inputs and discharges of effluents and partially treated sewage from many points throughout its tidally mixed zone. Recently, changes brought about in the estuary like reclamation and consequent shrinkage of the backwaters and the discharge of pollutants have made an adverse impact on the potential of aquatic ecosystems that used to support high levels of bioproductivity and biodiversity. The construction of Thannirmukham bund and Thottapally spillway to prevent salt water penetration into the paddy fields during pre-monsoon has led to serious ecological problems by interrupting the natural ebb and flow of tides. The hydrography, floral and faunal composition – its spatial and temporal variation plus assessments of the impact of the anthropogenic activities are presented in this review. An attempt to critically evaluate the status of the estuary from the biological and pollutional stand point is also done.     

The Høylandet area – patterns and processes of a pristine boreal-subalpine ecosystem – a synopsis

The research activities on soil–freshwaterinteractions and freshwater biotic structure andprocesses in the Høylandet area during the years 1986–89are presented in this issue ofHydrobiologia. The 9 papers cover a range of topicsfrom physiochemical gradients and processes in soilsand freshwaters to selected aspects of freshwaterbiotic community structure and temporal variability.This synopsis aims (a) to present an overview of majorfindings, (b) to interpret the results in the contextof air pollution effects and (c) to outlinesuggestions for future research activities inHøylandet. The area has a sub-oceanic climate varyingfrom 1100 to 2200 mm of precipitation normallyoriginating from unpolluted airmasses from the NorthAtlantic. It is chemically dominated by sea salts, haslow concentrations and low deposition of mineralacids. The catchment geology is variable and complexand consists mainly of various granites and gneisses.The soils are undisturbed ancient soils,primarily iron podzols associated with forests, orintact histosols with strong organic characterassociated with mires, often quite acidic.They are sensitive because occurrence of predominantlyinsoluble unstable Al-complexes may leach out ifexposed to anthropogenically acidified soil drainagewater and turn up as toxic inorganic aqueous Al insurface runoff. Small amounts of locally generatednitrogen compounds are mostly retained in thecatchment. The water qualities of these Høylandetsites are run by inputs of sea salts, hydrologicalprocesses including dilution of the base flow, orlateral surface or overland flow and in-catchmentprocesses. Relative to affected areas, it appears thatthe inputs and catchment processes are in balance,i.e., that the inputs of strong acid anions, hydrogenions and sea salts are equilibrated by internalweathering and other processes and integrated withinapparently intact biogeochemical cycles. The overallresult is that these soils remain a net source ofalkalinity to the runoff. These results are confirmedby regional studies of water quality both at low andhigh flow which show that the humus and ionic contentof the water decreased with elevation, headwatersbeing more dominated by sea salts and dilutionprocesses. Excess sulphate concentrations are low, andfew if any sites appear anthropogenically acidified,the most acid pHs reflecting presence of natural weakorganic acids.The resulting surface water quality allows a diverseaquatic fauna and flora with representatives of manyacid-sensitive groups. The fish fauna consists ofself-reproducing salmonid populations with normaldemography and ecological interactions. Despite highin-lake mortality, both brown trout and Arctic charrexhibited normal age-class compositions, with noindication of the recruitment failure or highpost-spawning mortality commonly observed inacid-stressed situations. The zooplankton and benthos in the lakesare inhabited by populations of several acid sensitivespecies, like Daphnia spp and Gammaruslacustris, and with dominance of mayfly species ofthe genus Baetis in the stream fauna. Thediatom flora includes many species which are rare orabsent in acidified waters. The observed gradients indiversity and biomass seem dominated by localenvironmental conditions which reflect natural ratherthan man-made processes. The pristine nature of thearea also emerges from the paleoecological studies inLake Røyrtjønna which show that the low acidity ofthis lake evironment has persisted from preindustrialtill present times. Suggestion for future researchactivities in Høylandet are outlined.     

Structure-function relationship of type-IV prepilin peptidase of Pseudomonas aeruginosa – a review

The bifunctional enzyme prepilin peptidase (PilD) from Pseudomonas aeruginosa is a key determinant in both type-IV pilus biogenesis and extracellular protein secretion, in its roles as a leader peptidase and MTase. It is responsible for endopeptidic cleavage of the unique leader peptides that characterize type-IV pilin precursors, as well as proteins with homologous leader sequences that are essential components of the general secretion pathway found in a variety of Gram-negative pathogens. Following removal of the leader peptides, the same enzyme is responsible for the second posttranslational modification that characterizes the type-IV pilins and their homologues, namely N-methylation of the newly exposed N-terminal amino acid residue. This review discusses some of the work begun in order to answer questions regarding the structure-function relationships of the active sites of this unique enzyme.     

Interaction of porphyrins with heme proteins – a brief review

In the past years, in our laboratory, several cell lines have been generated starting from a human liver (H7). Some of them have been used successfully in studies of the infection with and propagation of Hepatitis B and Hepatitis C viruses. Recently, several lines of evidence indicated that the origin of these cell lines was uncertain. Therefore, we now have determined the genetic characteristics of these cell lines in comparison to HepG2 cells received from ATCC and to HepG2 isolates grown at other laboratories. Quadruplex fluorescent short tandem repeat (STR) typing and karyotyping were performed. In addition, some biochemical characteristics of selected clones were studied. Genetically, all H7-derived cell lines were identical to HepG2 cells. However, some liver-specific functions varied between the different sub-cloned lines. The H7-derived cell lines that were generated proved to be sub-cloned lines of HepG2. The problem of cross-contamination during cloning of cell lines appears to be not uncommon. We found that two out of six HepG2 isolates obtained from other laboratories were not derived from the same individual as the original HepG2 cells. Therefore, STR typing should be applied as a rapid and sensitive technique to determine and monitor the origin of cell lines and to safeguard against contamination.     

Maternal age and trisomy – a unifying mechanism of formation

The mechanism of trisomy formation and its relationship to increased maternal age is not understood. Molecular analysis of the pattern of inheritance of DNA markers in trisomy families shows trisomies can be grouped according to whether the affected chromosomes inherited from their mothers are heterozygous or homozygous with respect to the centromeres. Furthermore, molecular analysis reveals that those that are heterozygous have fewer chiasmata, which are located more distally, while those that are homozygous have more chiasmata proximally located. Cytogenetic analysis of human oocytes shows that the kind of imbalance predicted by the classic hypothesis of nondisjunction, i.e. extra whole chromosomes at the second metaphase, is rarely found, whereas the common expression of imbalance is seen as single chromatids. We hypothesise that one mechanism links these data: the mechanism depends on the prediction from the cytogenetic data that cohesion within the bivalent complex is severely weakened during the extended dictyate stage in older women. Consequently, when meiosis resumes, at the time of ovulation, the bivalent emerges as four chromatids held together only by its chiasmata. In accordance with the rules of orientation on the spindle, the final balanced shape of the configuration achieved at metaphase I, in this case determined by the position of the chiasmata, will dictate whether the subsequent segregation of the chromatids will result in their heterozygosity or homozygosity. It follows that the concept of "first division" and "second division" errors, i.e. of nondisjunction originating at first or second meiotic division as defined by centromeric hetero- or homozygosity, may be erroneous.