Covalent coupling of pullulanase to an acrylic copolymer using a water soluble carbodi-imide

Pullulanase (EC 3.2.1.9) prepared from a culture of Acrobacter aerogeneshas been covalently bound to an inert crosslinked copolymer of aerylamide-acrylic acid by using a water-soluble carbodi-imide. The binding yield based on the amount of added pullulanase was 34%. The residual enzymic activity was 43%, of that of free enzyme. Coupling in the presence of the substrate pullulan gave a 5-fold increase in activity over that obtained when substrate was lacking. The effect of different carbodi-imide concentrations on the coupling has been investigated. The isoelectric point of the pullulanase preparation (3.5–4.0) was determined using isoelectric, focusing, in order to find optimal pH conditions for the coupling procedure. The immobilized pullulanase in a packed bed column was used to debranch amylopeetin to low molecular weight amylose.     

Clostridium perfringens (Holland) as an indicator of human effluent in the sediment of Lake Tuomiojärvi,central Finland

The horizontal and vertical distribution of the gram-positive, non-motile, spore-forming and rod-shaped bacterium Clostridium perfringens Holland was studied. The aim of the study was to estimate the quantity of C. perfringens at different depths of the sediment and evaluate the effect of human effluent which the lake received between 1940 and 1956. C. perfringens lives in the colon of man. Because it is spore forming and cannot multiply under a temperature of 20 °C and, according to the studies of Seppänen et al. (1979) it can be at least 300 years old, it may be a suitable paleolimnological indicator of pollution by human effluent. The results showed that the amounts of Clostridium increased at the same level where redox potential decreased in the sediment due to the beginning of effluent disposal at a depth of 40 mm. The maximum number of Clostridium colonies occurred between 0–30 mm depth.     

The D blood group system of the horse1

Three new horse blood group factors designated E₂, E' and Y were described. Evidence was presented that these three factors as well as the factors D, J and E₁ known before, belong to the D system established by Stormont & Suzuki (1964). That system was thus extended from being a two factor, three allele system, to the most complex system known in the horse so far. It was demonstrated that the D system is closed through the factors E₂ and E'. However a few exceptions to that rule were encountered. A minimum of 10 alleles, two of which were extremely rare seemed to control the system. Frequencies of the factors and the genes of the system were given for the Swedish Trotter breed and the North-Swedish Horse breed.     

Temporal development of biodiversity of macrophytes in newly established lakes

1. Every year, a vast number of wetlands are constructed to restore ecosystem function and biodiversity, thus counteracting massive historical losses by reclamation to farmland. However, our knowledge of the long-term effects on biodiversity, particularly of large systems such as lakes, is very limited.
2. Our objective was to follow the development of macrophytes over 3–4 decades in 24 new, shallow, eutrophic lakes in order to test the hypotheses that: (1) species richness reaches a maximum after some years and then declines; and (2) species composition changes substantially from small early colonisers to taller, competitive later colonisers, which causes ongoing high β-diversity.
3. A generalised linear mixed-effect model showed that species richness was related to lake size, phosphorus concentration and spatial setting, which are known to influence natural lakes as well. Moreover, species composition and richness were affected by lake age. Species colonised rapidly and richness peaked at an intermediate age and then declined.
4. Temporal species turnover within lakes was high in three lake age groups of ≤10, 11–20 or >20 years since establishment, although lowest after 11–20 years. Species replacement tended to contribute most to β-diversity in the youngest lakes, whereas richness fluctuated in older lakes and appeared to contribute most to temporal turnover there.
5. Early colonisers in ≤10-year-old lakes were commonly replaced by tall canopy-forming species in 11–20-year-old lakes, probably as a result of increasing competition for light and space over time. After 20 years, rootless Ceratophyllum submersum as well as species with floating and emergent leaves became dominant, potentially due to the gradual accumulation of more organic sediment difficult to root and grow in, along with gradually reduced light penetration in the water.
6. Establishing new lakes for biodiversity remains a challenge because of the falling richness and continuous species turnover with lake age, but our results suggest that constructing large, nutrient-poor lakes in species-rich landscapes ensures the best prerequisites for obtaining diverse communities.