Lactate from cultures of Lactobacillus casei recovered in a fluidized bed column using ion exchange resin

Summary Lactic acid produced by continuous culture of L.casei in an upflow packed bed reactor, was recovered with Amberlite IRA 400 in a fluidized bed column. Bed expansions of 1.25 and 2.25 were applied. Reutilization did not alter the capability of net recovery of 0.048 ± 0.01 g lactic acid/g resin. When 2200 cm/h of ascensional velocity was used, (bed expansion of 2.25), the resin adsorbed 39.3% of the initial lactic acid and 63.5% was eluted. This resin supported the highest exchange capacity of 0.126 g lactic acid/g resin. Applying high flow rates, the process has potential industrial applications due to the short time employed.     

Laser light-scattering characterization of mitochondrial complex III-Triton X-100-phospholipid mixed micelles

Bovine-heart mitochondrial complex III was purified in the presence of Triton X-100, and the size and shape of the resulting protein-surfactant-phospholipid mixed micelles were investigated by laser light-scattering. The protein appears to be present in the form of a dimer, irrespective of temperature (between 25 and 40 degrees C) and protein concentration (between 0.5 and 5 mg/ml). The molecular weight of the micelle increases with temperature from 600 000 (25 degrees C) to 692 000 (40 degrees C). The variation of the solvent second virial coefficient in this temperature range suggests that, with increasing temperature, some of the free surfactant molecules become integrated in the mixed micelles. The average quadratic radius of gyration of these is of 42 +/- 5 nm, corresponding in our case to an ellipsoidal shape.     

Synthesis and structure-activity relationship of 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives: a novel series of 5-HT(2A/2C) receptor antagonists. Part 2.

Following the programme started at Janssen Research Foundation searching for 5-HT(2A/2C) antagonists, we now report on the synthesis of a series of substituted 2-(Dimethylaminomethyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives. The 5-HT(2A), 5-HT(2C) and H(1) receptor affinities as well as the mCPP antagonistic activity of the compounds synthesised is described.     

Relative Dominance Affects Use of Scent-Marked Areas in Male Snow Voles Chionomys nivalis

We conducted a laboratory experiment to examine whether dominance status affects the use of locations occupied (i.e. scent-marked) by same-sex conspecifics among wild-caught snow vole males ( Chionomys nivalis ). Given that the costs of invading scent-marked areas should partially depend on the intruder's competitive ability, we hypothesised that, once a dominance relationship has been established with the owner of marks, the use of these areas by males would vary differently between dominant and subordinate individuals. Before any previous experience with the owner, scented substrates and nests were highly attractive to all males, indicating a general preference for recently occupied areas. However, after relative social status was established through direct interaction the subsequent response of males was altered differently, subordinate individuals reducing the use of marked areas to a much greater extent than dominants. Competitive relationships between male C. nivalis were found to be influenced by differences in body weight, larger males tending to display a more dominant pattern of behaviour. Our results reveal that male C. nivalis may require some direct experience with potential opponents to modulate their response towards occupied locations. Additionally, we suggest that the ability of males to conditionally respond to social signals from particular competing conspecifics might be used to lower the costs of prospective agonistic interactions.     

TWO NEW GENERA OF BRAZILIAN BAMBOOS RELATED TO GUADUA (POACEAE: BAMBUSOIDEAE: BAMBUSEAE)

Of all the genera of woody bamboos described from America, only three have pseudospikelets—Atractantha, Elytrostachys, and Guadua. The former two have pseudospikelets with an elongated rachilla internode that precedes the floret, making it pedicellate; they also share a type of leaf anatomy that separates them from the latter. The two new genera herein described, Criciuma and Eremocaulon, show most similarity to species of Guadua, both in spikelet morphology and in leaf anatomy. The study of these new taxa has helped to clarify the limits of New World genera with pseudospikelets and strengthened the case for maintaining Guadua as a genus distinct from its Old World counterpart, Bambusa. We are now able to discern a New World line of bamboos that includes Criciuma, Eremocaulon, and Guadua, separate from an Old World line that includes Bambusa, Dendrocalamus, and several other genera.     

Cyanide-resistant respiration in photosynthetic organs of freshwater aquatic plants

The rate and sensitivity to inhibitors (KCN and salicylhydroxamic acid[SHAM]) of respiratory oxygen uptake has been investigated in photosynthetic organs of several freshwater aquatic plant species: six angiosperms, two bryophytes, and an alga. The oxygen uptake rates on a dry weight basis of angiosperm leaves were generally higher than those of the corresponding stems. Leaves also had a higher chlorophyll content than stems. Respiration of leaves and stems of aquatic angiosperms was generally cyanide-resistant, the percentage of resistance being higher than 50% with very few exceptions. The cyanide resistance of respiration of whole shoots of two aquatic bryophytes and an alga was lower and ranged between 25 and 50%. These results suggested that the photosynthetic tissues of aquatic plants have a considerable alternative pathway capacity. The angiosperm leaves generally showed the largest alternative path capacity. In all cases, the respiration rate of the aquatic plants studied was inhibited by SHAM alone by about 13 to 31%. These results were used for calculating the actual activities of the cytochrome and alternative pathways. These activities were generally higher in the leaves of angiosperms. The basal oxygen uptake rate of Myriophyllum spicatum leaves was not stimulated by sucrose, malate or glycine in the absence of the uncoupler carbonylcyanide-m-chlorophenylhydrazone (CCCP), but was greatly increased by CCCP, either in the presence or in the absence of substrates. These results suggest that respiration was limited by the adenylate system, and not by substrate availability. The increase in the respiratory rate by CCCP was due to a large increase in the activities of both the cytochrome and alternative pathways. The respiration rate of M. spicatum leaves in the presence of substrates was little inhibited by SHAM alone, but the SHAM-resistant rate (that is, the cytochrome path) was greatly stimulated by the further addition of CCCP. Similarly, the cyanide-resistant rate of O₂ uptake was also increased by the uncoupler.     

C-banding polymorphism and the analysis of nucleolar activity in Dasypyrum villosum (L.) Candargy,its added chromosomes to hexaploid wheat and the amphiploid Triticum dicoccum — D. villosum

Summary C-banding patterns and nucleolar activity were analyzed in Dasypyrum villosum, its added chromosomes to hexaploid wheat and the hexaploid amphiploid Triticum dicoccum-D. villosum. Two different populations of the allogamous species D. villosum (2n= 14, VV) from Greece and Italy were analyzed showing a similar polymorphism for C-banding pattern. Six of the seven addition lines were identified by their characteristic C-banding pattern. No polymorphism between both members of each added alien chromosome was found. Furthermore, nucleolar activity and competition were studied by using silver staining procedure. In D. villosum only one chromosome pair, A, was found to be responsible for organizing nucleoli. The results obtained in the amphiploid and in the addition lines demonstrate that nucleolar activity is restricted to SAT-chromosomes 1B and 6B of wheat, while those of D. villosum remain inactive.     

Xfin: an embryonic gene encoding a multifingered protein in Xenopus.

The Xenopus laevis genome was screened for putative DNA-binding gene products by using the 'finger' region of the Drosophila gene Krüppel as a probe. The one gene detected, named Xfin, codes for a protein with 37 finger domains that comprise nearly 90% of the protein. In the light of studies by Rhodes and Klug (Cell, 46, 123-132, 1986), these data suggest that the Xfin protein has the capacity to bind an unusually large stretch (185 bases) of DNA. The Xfin gene is expressed as a maternal and zygotic mRNA that undergoes extensive polyadenylation changes during early development. The Xfin mRNA expression pattern and the potential DNA binding activity of the protein point to the possibility that the Xfin gene may have a role in controlling gene activity during early embryonic development.     

Mapping of the gene for anti-müllerian hormone to the short arm of human chromosome 19

The gene coding for human anti-Müllerian hormone (AMH) was localized to subbands p13.2----p13.3 on chromosome 19, using in situ hybridization and Southern blot analysis of a panel of man-mouse and man-hamster somatic cell hybrids.