The skeletal isotopic composition as an indicator of ecological and physiological plasticity in the coral genus<Emphasis Type="Italic"> Madracis</Emphasis>

Three species of the reef coral genus Madracis display skeletal isotopic characteristics that relate to depth, colony topography, and consequently to coral physiology. The joint interpretation of skeletal ¹³C and ¹⁸O provides information on the ecological plasticity and adaptation to depth of a coral species. Isotopic results are most easily understood in terms of kinetic effects, which reduce both ¹⁸O and ¹³C below isotopic equilibrium values, and metabolic effects, which only influence the skeletal ¹³C. Madracis mirabilis is adapted to depths shallower than 20 m, and shows the greatest range in kinetic effects and the strongest metabolic ¹³C enrichments caused by symbiont photosynthesis. Madracis formosa lives deeper than 40 m, and shows a reduced range of kinetic effects and relatively weak metabolic ¹³C enrichments. Madracis pharensis inhabits depths from 5 to >60 m, and does not attain the strength of kinetic effects of either of the other two species, apparently because it is not quite as well adapted to rapid growth at either extreme.     

Starch hydrolysing enzymes in the developing barley grain

Summary The enzymes -amylase (-1, 4-glucan 4-glucanohydrolase, 3.2.1.1), -amylase (-1,4-glucan maltohydrolase, 3.2.1.2) and phosphorylase (-1,4-glucan: orthophosphate glucosyltransferase, 2.4.1.1) were assayed in whole grains of barley throughout the maturation period. -amylase and phosphorylase had peaks of activity between 25 and 30 days after anthesis. On the other hand the activity of -amylase in both the available and latent forms reached a maximum value at 35 days after anthesis which did not decrease thereafter. -amylase activity was also assayed throughout development in the endosperm, aleurone, testa pericarp and embryo. Latent -amylase reached a constant maximum value in endosperm at 35 days but available -amylase reached a peak of activity at 25 days and then declined to zero at 45 days. Only latent -amylase was associated with the aleurone layer and activity rose to a maximum value at 35 days. The testa pericarp had mainly latent -amylase whose activity fell from an early maximum at 21 days to zero at 35 days. No hydrolytic activity was associated with the embryo. The phosphorylase activity was low and mainly associated with the endosperm fraction.     

Enzyme-catalyzed synthesis of alkyl β-D-glycosides with crude homogenate ofSulfolobus solfataricus

Summary Crude homogenate of thermophilic archaebacteriumSulfolobus solfataricus, possessing a -glycosidase, has been used to synthesize different alkyl -D-glycosides starting from phenyl -D-glucoside, phenyl -D-galactoside and lactose as carbohydrate donors. High product yield (95% with respect to the carbohydrate donor) of octyl -D-glucoside has been obtained in a two-phase system containing 5% of water. The enantioselection for the galactosyl transfer to the secondary hydroxyl group of propane-1,2-diol is higher than that found using -galactosidase fromE. coli.     

Biphasic Modulation of GABAA Receptor Binding by Steroids Suggests Functional Correlates

Neuroactive steroids and other positive modulators of GABA_A receptors showed regional variation in both the efficacy and potency for modulation of [³⁵S]TBPS binding to rat brain membrane homogenates, with biphasic concentration-dependence. GABA present in the binding assays prevented the enhancement phase of the steroid concentration-dependence plot while the antagonists bicuculline and RU5135 prevented the inhibition phase. Using recombinant GABA_A receptors, expressed in insect cell line Sf9 using baculovirus, enhancement by steroids of [³⁵S]TBPS binding was sensitive to the presence of the 2 subunit and the nature of the subunit (122S > 12, 62, 622S, and 62). As in cerebellum, addition of RU5135 reduced the inhibitory phase and revealed a small enhancement of TBPS binding by neuroactive steroids. The subunit-dependent interactions of steroid and GABA site ligands are consistent with a three-state model in which the receptor mono-liganded by GABA or steroid has a different affinity for TBPS than the resting state, and the receptor biliganded by GABA, steroid, or both has little affinity for TBPS.     

Enzymatic basis for sialyl-Tn expression in human colon cancer cells

Sialyl-Tn antigen (SA2-6 GalNAc-Ser/Thr) is expressed as a cancer-associated antigen on the surface of cancer cells and its expression correlates with a poor prognosis in patients with colorectal and other adenocarcinomas. To understand the enzymatic basis of sialyl-Tn (STn) antigen expression, we used two clonal cell lines, LSB and LSC, derived from LS174T human colonic cancer cells. LSC cells express only the truncated carbohydrate antigen Tn (GalNAc-Ser/Thr) and sialyl-Tn on their mucin molecules, whereas LSB cells express elongated oligosaccharide chains. Both cell lines demonstrated similar activities of glycosyltransferases involved in the biosynthesis of elongated and terminal structures of complex O-glycans. However, LSC cells were unable to synthesize core 1 (Gal1-3GalNAc-) because the ubiquitous enzyme activity of UDP-Gal:GalNAc-R 3-Gal-transferase (core 1 3-Gal-transferase) was lacking. Core 1 3-Gal-transferase could not be reactivated in LSC cells by treatment with sodium butyrate or by in vivo growth of LSC cells in nude mice. In contrast, LSB cells were able to synthesize and process core 1 and core 2 (GlcNAc1-6 (Gal1-3) GalNAc-). LSC cells represent the first example of a non-hematopoietic cell line which lacks core 1 3-Gal-transferase activity. The lack of core 1 3-Gal-transferase in LSC cells explains why they are incapable of forming the common mucin O-glycan core structures and are committed to synthesizing the short Tn and STn oligosaccharides. These findings suggest that the activity of core 1 3-Gal-transferase is an important determinant of the STn phenotype of colon cancer cells.     

Cytokinesis in the green alga Eremosphaera viridis: Plasmalemma formation from “open membranes”

Summary Cytokinesis in the unicellular chlorococcalean alga Eremosphaera viridis de Bary has been investigated by electron microscopy of thin sections. The new plasmalemmata of the daughter cells in this organism form centrifugally within a phycoplast. Unlike other cell division systems each new plasmalemma is formed, not by the fusion of vesicles, but rather by the fusion of open membranes which are characteristically heavily stained. Measurements of these open membranes reveal that they are 11 nm thick with a central 4,5 nm unstained portion. The possible origin of these open membranes as burst-open vesicles has been suggested from the presence of intensely straining vesicles in the vicinity of the cell equator. Calculations of vesicle and open membrane surface areas support this contention.     

Enzymatic studies on ninhydrin-positive compounds exuded by root tips of pea seedlings

Summary The action of L-amino-acid oxydase, D-amino-acid oxydase and L-glutamic decarboxylase on ninhydrin-positive compounds present in root-tip exudates and root-scraping extracts of pea seedlings, is described. Results of Fukuda et al. are confirmed as to the presence of D-alanine in -glutamyl-alanine.The possible inhibitory effects of -L-glutamyl-D-alanine and of Unknown Y (most probably 2-alanyl-isoxazolin-5-one) on bacterial growth are discussed. re]19760809     

Limited Proteolysis of Bacillus thuringiensis CryIG and CryIVB δ-Endotoxins Leads to Formation of Active Fragments That Do Not Coincide with the Structural Domains

Bacillus thuringiensis true toxins consist of three domains: the N-terminal, -helical domain followed by two -structural domains. Their limited proteolysis does not proceed at the domain boundaries, but is directed to the loops within the domains. There are at least two patterns of the limited proteolysis of true toxins. The first pattern, observed for CryIA and CryIVD -endotoxins, results in the proteolysis of the loops connecting -strands of the second domain. The second pattern, detected for CryIG and CryIVB proteins, consists in the cleavage of the loop connecting the fifth and the sixth -helixes of the first domain. The choice between the routes depends on the size, sequence, and dynamics of the loop that define its accessibility to a proteinase. Bioassay of CryIG and CryIVB -endotoxin fragments indicates that only two -helixes, the sixth and the seventh within the first domain, followed by the two -structural domains are sufficient for the insecticidal activity.     

Molecular organization of the human CD3 gene family on chromosome 11q23

The genes encoding three invariant components of the human T-cell antigen receptor, the CD3 , , and chains, are located on human chromosome 11 at band q23. We isolated cosmid clones containing the human CD3 and chain genes in vectors designed for rapid and efficient chromosome walking. The human CD3 gene was located in the region immediately downstream of the CD3 and genes using synthetic oligonucleotide probes and the localization of this gene confirmed by DNA sequencing. Detailed restriction mapping of the CD3 locus demonstrated that all three CD3 subunits are encoded within 60 kb of DNA with the CD3 gene located 26 kb downstream of the CD3 and genes. Analysis of genomic DNA on pulsed field gels using probes isolated from these cosmid clones defined a physical map of 750 kb spanning the CD3 locus on human chromosome 11g23. The CD3 genes thus comprise a multigene family encoding cell surface components important for transmembrane signaling on T lymphocytes. The arrangement of these genes suggest that they may share common regulatory elements for the control of gene expression during T-cell ontogeny.     

Methodological problems in evolutionary biology VIII. Biology and culture

Biology cannot accommodate all aspects of culture. Aspects of culture that a biological approach can take into account can be covered by the biological categories of phenotype and environment. There is no need to treat culture as a separate category. Attempts to elaborate biological explanations of cultural variation will meet with success only if biologists expand theories of development, and integrate them in evolutionary biology. The alternative — elaborating the idea of so-called cultural inheritance — makes little sense from a biological point of view.     

Correlation between 15N NMR chemical shifts in proteins and secondary structure

Summary An empirical correlation between the peptide ¹⁵N chemical shift, ¹⁵N_i, and the backbone torsion angles _i, _i–1 is reported. By using two-dimensional shielding surfaces (_i1–1), it is possible in many cases to make reasonably accurate predictions of ¹⁵N chemical shifts for a given structure. On average, the rms error between experiment and prediction is about 3.5 ppm. Results for threonine, valine and isoleucine are worse (4.8 ppm), due presumably to ₁-distribution/-gauche effects. The rms errors for the other amino acids are 3 ppm, for a typical maximal chemical shift range of 15–20 ppm. Thus, there is a significant correlation between ¹⁵N chemical shift and secondary structure.     

Developmental changes in neutral glycosphingolipids of mouse placenta

The mammalian placenta is a unique organ for the study of developmental changes. Placentas of laboratory animals such as the mouse allow for the determination of the exact stage of pregnancy, which cannot be achieved with human placenta. In this study, neutral glycosphingolipids were isolated from mouse (inbred strain C57BL/6) placentas, from day 10 to day 18 of gestation, and were separated by high performance thin layer chromatography. Densitometric measurements after orcinol staining showed, at day 10 of gestation, the presence of mono-, tetra-, tri- and dihexosylceramide in decreasing quantities, as well as four unidentified spots. On day 12, the glycosphingolipid composition changed with the disappearance of the unidentified spots and the appearance of an orcinol positive spot migrating similarly to the Forssman antigen; no further changes occurred between days 12 and 18 of gestation. The identity of the Forssman-like glycosphingolipid with the Forssman antigen was established by binding of¹²⁵I labelledHelix pomatia agglutinin (-GalNAc specific) to glycosphingolipids separated on high performance thin layer chromatography plates, and by the reaction of the isolated glycosphingolipid with a monoclonal anti-Forssman antibody. The appearance of the Forssman antigen at day 12 of gestation coincided with the day of final maturation of the mouse placenta and subsequent cessation of growth, suggesting a possible role of the glycosphingolipid during embryonic development.Abbreviations asialo-GM₁ Gal 3GalNAc4Gal4Glc1Cer - BCIP 5-bromo-4-chloro-3-indolylphosphate - DHC lactosylceramide, Gal4Glc1Cer - Forssman antigen GalNAc3GalNAc3Gal4Gal4Glc1Cer - globoside GalNAc3Gal4Gal4Glc1Cer - GSL glycosphingolipids - HPA Helix pomatia agglutinin - HPTLC high performance thin layer chromatography - MHC galactosylceramide, Gal1Cer - MHC glucosylceramide, Glc1Cer - PBS phosphate-buffered saline - PNA peanut agglutinin - PVP poly(vinylpyrrolidone), mol. wt 40 000 - SBA soybean agglutinin - THC trihexosylceramide, Gal4Gal4Glc1Cer. To whom correspondence should be addressed.     

Wellenmessungen im Seegebiet der Piep (Deutsche Bucht)

Zusammenfassung 1. In Form von Seegangscharakteristiken werden Meßergebnisse über mittlere und maximale Wellenhöhen sowie mittlere Perioden des Seegangs an vier Beobachtungs-stationen im Seegebiet der Piep (Deutsche Bucht) mitgeteilt.2. Die Ergebnisse zeigen, daß die Abhängigkeit der maximalen Wellenhöhen von der Windrichtung sehr ausgeprägt die Topographie des Beobachtungsortes widerspiegelt. Für die mittleren Wellenhöhen ist das nicht in gleichem Ausmaße der Fall, es gilt nur für einigermaßen frei zur See liegende Stationen.3. Als maximale Wellenhöhe bei WSW-Wind von Beaufort 10 an der Station Trischen ergab sich 3,2 m, bei Tertius, Scholloch und Tonne 16 2,8; 2,5 bzw. 2,4 m.

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Wave measurements in the sea area of the Piep (German Bight)

In form of wave characteristics, results of measurements of mean and maximum wave heights as well as mean periods of the sea at four observation stations in the sea area of the Piep (German Bight) are presented. The results show a very strong dependence of the maximum wave heights upon the topography of the observatory position. In case of mean wave heights this dependence is not so strong for stations with near coast positions. At Beaufort 10, as maximum wave height at station Trischen 3.2 m resulted; at Tertius, Scholloch and Tonne 16 maxima were 2.8, 2.5 and 2.4 m, respectively.

     

Conservation status of parrot populations in an Atlantic rainforest area of southeastern Brazil

A census of four species of syntopic parrots was carried out using distance sampling methods on São Sebastião island, SE Brazil. Most of the 33593 ha island is covered by mature and secondary Atlantic rainforest. Almost 80% of these forests are within the Ilhabela Park. Although the species counted have marked differences in size and weight, density (individuals/km²) and estimated population size in 23500 ha of well-preserved forests were similar: Amazona farinosa (13.82±5.94; 3247±1395), Pionus maximiliani (15.79±7.04; 3712±1654), Brotogeris tirica (15.05±4.87; 3537±1143) and Pyrrhura frontalis (13.06±5.53; 3068±1298). Encounter rates of Forpus crassirostris and Pionopsitta pileata were very low, which suggests that there is only a small population of these species on the island. The São Sebastião forests still support healthy populations of parrots. Although woodpecker population estimates on the island are large enough to provide nesting sites for parrots, competition for holes with other secondary cavity nesters such as toucans, flycatchers and tytiras, and the selective cutting of dead trees for canoe construction, which is a common practice on the island, may limit hole availability for parrots.     

The structure of two distinct pancreatic amylase genes in mouse strain YBR

The amylase complex on mouse chromosome 3 encodes both salivary and pancreatic amylase. It appears that one active gene is present for salivary amylase, whereas pancreatic amylase in some strains is coded by at least 4, and perhaps by more than 10, genes. Strain YBR is different from other strains in that it produces twice as much salivary amylase. Pancreatic amylase in YBR is present as two different protein forms, A and B, the sum of which amounts to only one-third of that in, for instance, strain A/J. YBR chromosomal DNA was cloned in phage , followed by restriction and heteroduplex analysis of recombinant phages carrying amylase genes. Among 32 phage isolates, 5 carried parts of the salivary amylase sequence. The remaining phage isolates contained pancreatic amylase-like sequences and represented three nonoverlapping genomic regions, i.e., one of 34 kb containing a complete gene, PAN-II; another of 41 kb with a complete but different gene, PAN-I, plus a truncated gene, PAN-1; and finally, one of 23 kb with another truncated gene, PAN-2. Parts of the amino acid sequence of A and B have previously been determined, and we report here the sequencing of a 4-kb DNA fragment from Pan-II which establishes that this gene codes for B.This work was supported by the Danish Natural Science Research Council.     

Improved in situ β-galactosidase staining for histological analysis of transgenic mice

The present study describes a novel method for the histochemical demonstration of -galactosidase activity on tissue sections. We have replaced 5-bromo-4-chloro-3-indolyl--D-galactoside (X-Gal) with 5-bromoindolyl--o-galactopyranoside (Bluo-Gal) as a chromogenic substrate for the bacterial -galactosidase (lacZ). After -galactosidic cleavage, Bluo-Gal precipitates in form of fine birefringent crystals, whereas X-gal gives rise to an amorphous precipitate. Upon microscopic examination under polarized light, the crystals emit a strong signal consisting of yellow reflected light. This property of Bluo-Gal results in greatly enhanced sensitivity of the staining method for -galactosidase and allows for optimal morphological resolution. To exemplify the applications of this technique, the expression is demonstrated in transgenic mice of -galactosidase driven by a fragment of the human tissue-type plasminogen activator promoter.     

Ultrastructure of the new neuromuscular junctions formed during reinnervation of rat soleus muscle by a “foreign” nerve

Summary In rats the fast fibular nerve was transposed to the slow soleus muscle outside the original innervation band. Formation of new neuromuscular junctions was induced by cutting the soleus nerve after different periods of time. The morphological maturation of these junctions was studied by electron microscopy.New neuromuscular junctions do not form when the original innervation is left intact.Three to five days after denervation, vesicle-laden terminal boutons contact muscle fibers with only the basal lamina of the latter intervening. Three weeks after denervation, most boutons are larger and postsynaptic folds are present, although younger stages are also seen. Sixteen weeks after denervation, the neuromuscular junctions appear mature. This corresponds well with electrophysiological findings in the same material.The fully developed neuromuscular junctions sixteen weeks after denervation possess postsynaptic folds similar to those of normal fast muscle fibers. This suggests that the fast fibular nerve rather than the slow soleus muscle fibers determines the morphology of the postsynaptic folds.Possible trophic neuromuscular interactions are discussed.The authors are indebted to Mrs. Jorunn Line Vaaland, Miss Bjørg Riber, and Miss Berit Branil for technical assistance. Dr. T. Lømo and Dr. C. Slater have contributed constructive criticism and advice     

Movements and diurnal behaviour patterns in a Baltic grey seal (Halichoerus grypus)

A sub-adult grey seal was caught and tagged with a satellite relay data logger at Tihällan (61°2800N, 17°2540E), Sweden, on 21 August 1992. We tracked it for 115 days during which time we recorded 841 locations, data on 3556 dives and 80 haulout periods. It travelled 730 km in the first 12 days to the southern Archipelago Sea. It stayed most of the remaining time within 25 km of a haulout site, with a major exception of an 8-day trip of 520 km. Dive shape and swimming activity were used to distinguish dive types. Square-shaped foraging dives were more common over the midday period. Haulout periods were more common during the night.     

Single-strand conformational polymorphism and direct sequencing applied to carrier testing in families with ornithine transcarbamylase deficiency

Single-strand conformational polymorphism (SSCP) and direct sequencing were used to confirm or deny carrier status in three families with ornithine transcarbamylase (OTC) enzyme deficiency. Two male probands with late onset OTC deficiency, whose private mutations were previously characterized, inherited the mutations form their heterozygous mothers. One of the heterozygous mothers had a false negative allopurinol test. Three female siblings of the two male probands were tested, one proved to be a carrier of the respective mutation while the other two were found to have normal alleles. In the third family, the proband was a female with late onset presentation of OTC deficiency. We found a new point mutation in this girl consisting of a guanine-tocytosine transversion at nucleotide 520 resulting in a substitution of proline for alanine at amino acid 142 of the mature OTC protein. We confirmed that this mutation occurred spontaneously and that neither of the two parents carries this mutation. We conclude that SSCP, in conjunction with direct sequencing, is a useful technique that can be practically applied for carrier testing in families with OTC deficiency.     

Problems in estimating growth rates of marine phytoplankton from short-term14C assays

Growth rate estimates () of phytoplankton populations that were sampled from nitrogen-limited continuous cultures and then incubated for short durations in batch culture with added¹⁴C-HCO₃ ^– were significantly different than steady-state growth rates () for 3 of 5 marine phytoplankton species. Two diatoms,Thalassiosira weissflogii andChaetoceros simplex, displayed virtually identical growth rates (=) over a wide range of, whereas for a third diatom,Phaeodactylum tricornutum, was overestimated by an average of 40% compared to. In contrast, was underestimated by the¹⁴C technique for the two remaining species: up to 40% at a steady-state of 1.0 day^–1 for the chlorophyteDunaliella tertiolecta and up to 100% at of 1.4 day^–1 for the haptophytePavlova lutheri. For the latter two species the divergence between and appeared to increase with increasing steady-state. A simple model of labeled and total carbon flow between the aqueous phase and cellular biomass was constructed to demonstrate that respiration was negligible when=, but was significant when>. In the cases in which<, a rapid physiological alteration presumably took place once the steady state was disturbed and cells were placed in the incubation chambers, which perhaps was related to the nutritional state of the cultures at the time of sampling. Questions thus are raised regarding our ability to measure accurately primary productivity from shipboard experiments with confined samples of phytoplankton from nutrient-impoverished waters that probably are less hardy than the laboratory cultures used in these studies.