Present and future needs for algae and algal products

A review of the present needs, mainly for production of phycocolloids and food condiments, is given. Supply and demand vary from balanced, in some, to disproportionate in other fields. World-wide shortage of agarophytes contrasts with huge, unexploited beds of brown seaweeds.In future, partly conflicting trends will decide the needs for algae and algal products. Growth in the human population, pollution, overexploitation of land and lack of freshwater will encourage use of seaweeds. Modern biotechnology will favour this development, but will also be a serious threat to industrial exploitation of seaweeds. Future uses of marine algae will be decisively influenced by the effort put into and the results coming out of seaweed research.     

The 'Gut index', a new parameter to measure the gross nutritional state of arctic char, Salvelinus alpinus (L.) and brown trout, Salmo trutta L.

The main energy reserves in brown trout, Salmo trutta and Arctic char, Salvelinus alpinus are located in the abdominal cavity and the musculature. The energy content of the rest of the intestines after removal of the gonads, swim bladder, and liver is a good parameter to assess the gross nutritional state of Arctic char and brown trout. This method is laborious, but analysing the dry matter fraction (or the water content) of the same organs instead of their energy content is a practical alternative. The dry matter fraction of these organs expressed as a percentage of its wet weight is here called the 'Gut index'.     

Excitatory Amino Acids: Studies on the Biochemical and Chemical Stability of Ibotenic Acid and Related Compounds

The complex pharmacological profile (excitation/inhibition) of ibotenic acid on single neurons in the mammalian CNS prompted studies on the stability of ibotenic acid and a number of structurally related excitatory amino acids under different in vitro conditions in the presence or absence of enzymes. Ibotenic acid, (RS)-3-hydroxy-4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-7-carboxylic acid (7-HPCA), (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and (RS)-alpha-amino-3-hydroxy-4-bromo-5-isoxazolepropionic acid (4-Br-homoibotenic acid) were all inhibitors of (S)-glutamic acid decarboxylase (GAD) in mouse brain homogenates, but only ibotenic acid was shown to undergo decarboxylation during incubation with brain homogenates. The formation of the decarboxylated product, muscimol, which primarily occurred in a synaptosomal fraction, was dependent on the presence of pyridoxal-5-phosphate (PALP) and was inhibited by (S)-glutamic acid, 3-mercaptopropionic acid (3MPA), aminooxyacetic acid (AOAA), and allyglycine, suggesting that ibotenic acid is a substrate for GAD. The overall decomposition rate for ibotenic acid (8.7 nmol min-1 mg-1 of protein), which apparently embraces other reactions in addition to decarboxylation to muscimol, was higher than the rate of decarboxylation of (S)-glutamic acid (3.2 nmol min-1 mg-1 of protein). At pH 7.4 and 37 degrees C, but in the absence of enzymes, none of the excitatory amino acids under study underwent any detectable decomposition, whereas ibotenic acid and 7-HPCA, but not AMPA and 4-Br-homoibotenic acid, decomposed, partially by decarboxylation, at 100 degrees C in a pH-dependent manner. In the presence of liver homogenates, ibotenic acid was also shown to decompose.(ABSTRACT TRUNCATED AT 250 WORDS)     

The importance of scale and spatial variables for the fungivorous beetle Bolitophagus reticulatus (Coleoptera, Tenebrionidae) in a fragmented forest landscape

Effects of isolation, habitat size and several microhabitat variables on presence/absence of the monophagous Bolitophagus reticulatus (L.) (Coleoptera. Tenebrionidae) were investigated in 58 forest fragments in an agricultural landscape (15 km²) in south-eastern Norway, All potential habitats of the beetle, dead Fomes fomentarius (L,) Kiekx basidiocarps (n = 587), were collected from trees (n = l85) within the study area. The basidiocarps were dissected and the number of B, reticulatus specimens (larvae, pupae and adults) counted. The material was analysed at four distinguishable spatial scales; basidiocarp-. tree-, tree-group- and forest island level. Different patterns of beetle presence emerged at the different scales, increasing habitat size and decreasing degree of isolation increased the probability of B, reticulatus presence at three (basidiocarp-, tree- and forest island level) and one (tree level) scales, respectively, whilst no such trends were found at the fourth level (tree-group level). Increasing insolation and thereby higher ambient temperatures, indicated by several microhabitat variables, improved the probability of beetle presence amongst the trees. The number of beetle specimens correlated positively with an increase in the habitat size at the tree level.     

The use of volatile cues in recognition of kin eggs by predatory mites

1. Several animal species are known to distinguish between their own eggs and eggs of unrelated conspecifics. However, the cues involved in this discrimination are often unknown. These cues were studied using the predatory mite Gynaeseius liturivorus Ehara.
2. Adult females of these predatory mites oviposit in clusters and avoid oviposition close to eggs laid by other females, resulting in reduced cannibalism between offspring. Because predatory mites are blind, it was tested whether volatiles of eggs were used as a cue for egg recognition.
3. Adult female predatory mites were offered volatile cues of their own eggs and of unrelated conspecific eggs, and females were prevented from contacting the eggs. Predatory mites oviposited closer to their own eggs than to unrelated eggs. This preference was observed even when one own and one unrelated egg were offered as a volatile source.
4. These results suggest that adult female predatory mites can determine kinship using volatiles released from the eggs.

     

A molecular phylogeny of the north‐east Atlantic species of the genus Idotea (Isopoda) with focus on the Baltic Sea

Today, the marine isopods of the genus Idotea Fabricius, 1798 consist of 26 accepted species. Most species can be found in the Northern Hemisphere. While some species have a cosmopolitan distribution, others are endemic to a few coastlines. In the Baltic Sea, Idotea species have a key role as important meso‐grazers. Only three species can be found in this brackish environment, I. balthica, I. chelipes and I. granulosa, while nine species are described from the whole European coast. The goal of the present study was to reconstruct the phylogeny of the genus Idotea and to test whether the Baltic low‐salinity tolerant species represent a single lineage within the genus. The phylogeny of north‐east Atlantic Idotea species was investigated based on a fragment of the nuclear gene 28S and the mitochondrial gene COI for eight Idotea species. The phylogenetic reconstructions showed that the genus Idotea might not be monophyletic. Neither I. linearis nor I. urotoma did belong to the separated and well‐supported Idotea clade of I. balthica, I. chelipes, I. emarginata, I. granulosa, I. metallica and I. pelagica. The three Idotea species found in the Baltic belonged to different lineages, with estimated COI‐based divergence time older than 7 Myr. This suggests that the tolerance to low salinity has likely evolved in the genus Idotea more than once.