Solution conformation and dynamics of a tetrasaccharide related to the LewisX antigen deduced by NMR relaxation measurements

¹H-NMR cross-relaxation rates and nonselectivelongitudinal relaxation times have been obtained at two magnetic fields (7.0and 11.8 T) and at a variety of temperatures for the branchedtetrasaccharide methyl3-O--N-acetyl-galactosaminyl--galactopyranosyl-(14)[3-O--fucosyl]-glucopyranoside (1), an inhibitor of astrocyte growth. Inaddition, ¹³C-NMR relaxation data have also been recorded atboth fields. The ¹H-NMR relaxation data have been interpretedusing different motional models to obtain proton–proton correlationtimes. The results indicate that the GalNAc and Fuc rings display moreextensive local motion than the two inner Glc and Gal moieties, since thosepresent significantly shorter local correlation times. The¹³C-NMR relaxation parameters have been interpreted in termsof the Lipari–Szabo model-free approach. Thus, order parameters andinternal motion correlation times have been deduced. As obtained for the¹H-NMR relaxation data, the two outer residues possess smallerorder parameters than the two inner rings. Internal correlation times are inthe order of 100 ps. The hydroxymethyl groups have also different behaviour,with the exocyclic carbon on the glucopyranoside unit showing the highestS². Molecular dynamics simulations using a solvated systemhave also been performed and internal motion correlation functions have beendeduced from these calculations. Order parameters and interproton distanceshave been compared to those inferred from the NMR measurements. The obtainedresults are in fair agreement with the experimental data.     

Sarsicopia polaris gen. et sp.n., the first platycopioida (Copepoda: Crustacea) from the Arctic Ocean,and its phylogenetic significance

A new genus of Platycopioida is described from a boxcore sample taken at a depth of 534 m in the ArcticBarents Sea. This is the deepest record ofPlatycopioida so far. Sarsicopia gen. n. is thesistergroup of a taxon comprising Platycopia and Nanocopia; the sistergroup ofthese is Antrisocopia. Sarsicopia gen. n.is the only platycopioid to retain 2 inner setae onthe second endopod segment P2–P4, and 8 setae in thethird endopod segment of P2. The male antennnule isremarkable in having a geniculation located betweenancestral segments XX and XXI. It is suggested thatthis flexure zone was already present in thegroundpattern of Copepoda. Platycopia and Nanocopia have secondarily lost thisgeniculation.     

Allozyme variability and phylogenetic relationships in the cultivated potato (Solanum tuberosum) and related species

Gene frequencies at 13 isozyme loci were determined in three South American taxa of cultivated potatoes [the diploid group (gp.) Stenotomum, the diploid subgroups (subgp.) Goniocalyx, and the tetraploid gp. Andigena ofS. tuberosum], in the diploid weed speciesS. sparsipilum, and in most of the main cultivars now raised in the Northern Hemisphere (the tetraploid gp. Tuberosum ofS. tuberosum). High levels of genetic variability (mean number of alleles per locus, percentage of polymorphic loci, and mean heterozygosity) were detected, being higher in tetraploid potatoes. An equilibrium among the evolutionary factors which increase genetic variability and artificial selection for maximum yield would explain the high uniformity of heterozygosity values we observed in both Andigena (0.36 ± 0.02) and Tuberosum (0.38 ± 0.01) cultivars.—The low value of genetic distance (D = 0.044) between Stenotomum and Goniocalyx does not support the status of species forS. goniocalyx.—In most isozyme loci, the electromorphs of gp. Andigena were a combination of those found in both gp. Stenotomum andS. sparsipilum, suggesting an amphidiploid origin of gp. Andigena from that two diploid taxa. The presence in Andigena of unique electromorphs, which were lacking in both gp. Stenotomum andS. sparsipilum, suggests that other diploid species could be also implied in the origin of tetraploid Andean potatoes. Furthermore, since Andigena were more related to Stenotomum (D = 0.052) than toS. sparsipilum (D = 0.241), the autopolyploidization of Stenotomum individuals and the subsequent hybridization with gp. Andigena may also have occurred. Thus, our study suggests a multiple origin (amphidiploidy, autoploidy, and hybridization at tetraploid level) of gp. Andigena.—Most of the electromorphs of gp. Tuberosum were also found in gp. Andigena; both the direct derivation of that group from the Andean tetraploid potatoes and the repeated introgression provided by breeding programmes could explain this result. However, the allele c of Pgm-B, present in 30 out of 76 Tuberosum cultivars from Northern Hemisphere as well as in 3 Chilean Tuberosum cultivars, lacks in the 258 Andigena genotypes sampled, suggesting that Chilean germplasm could have taken part in the origin of at least the 39% of the potato cultivars from Europe and North America analyzed here.—The distanceWagner procedure provides an estimate of a 30% of heterogeneity in the evolutionary divergence shown by different groups of cultivated potatoes. Diploid groups show a higher (22.5%) evolutionary rate than tetraploids, which can be attributed to both tetrasomic inheritance and facultative autofecundation that exists in Andigena and Tuberosum groups. Thus, artificial selection acting since 10000 years has not resulted in a higher rate of molecular evolution at the isozyme level in the tetraploids.     

Partial deletion of 4p16 band in a ring chromosome and wolf syndrome

Summary A new case of ring chromosome 4 in a 2-day-old female child with multiple malformations is described. By means of the GTG-banding technique, a karyotype 46,XX,r(4), (p16q35) was determined. The characteristics of the child's karyotype and the relationship with the structure of the chromosome, especially the location of the deletion that produces the syndrome, are compared with previous reports.     

Sympathetic control on salivary secretion by the parotid gland in rabbit. I. Effects on the unstimulated gland (author's transl)]

The sympathetic influences on the rabbit unstimulated parotid gland were studied. The experiments were carried out in anaesthetized rabbits with the Stenon aduct cannulated. Direct stimulation of the superior cervical ganglion elicits variable salivary flows. The high amylase content in the saliva points to a sympathetic secretory action upon acinar cells. The administration of alpha-adrenergic blocking agents (dihydroergotamine, phentolamine and phenoxybenzamine) clearly reduces and even abolishes the effect of the sympathetic stimulation upon flow. The administration of a beta-adrenergic blocking agent (propranolol) slightly reduces the sympathetic action. However the amylase activity is greatly reduced. All this suggests that the secretory effects on the fluid fraction should predominantly be alpha-adrenergic while on the secretion of enzymes the beta-receptors should play an important role.     

A family with a satellited Yq chromosome

Summary A large pedigree with a satellited Yq chromosome is described, Q, C, and NOR banding were performed. Family C proband suffers from a Klinefelter syndrome.     

Adaptation to chronic hypobaric hypoxia and sexual hormones

The role of the gonads and their hormones on body weight was studied in rats of both sexes submitted to chronic hypoxia and their controls at sea level atmospheric pressure. Intact rats were exposed to either 4 700 or 6 000 m simulated altitude in a hypopressure chamber. Castrated rats and castrated rats daily injected with either 0.5 mg of testosterone or 20 microgram of estradiol or the vehicle, were exposed to the higher altitude. The rat weight was recorded for a period of at least eight weeks. All groups of hypoxic male animals increased their weight significantly less than the controls at sea level. Also in castrated females and in castrated injected with testosterone or the vehicle the same pattern of weight curves was observed. On the contrary, groups of intact females and castrated females injected with estradiol did not show significant differences between hypoxic and control animals. Only in a group of smaller intact females (50-80 g) the body weight increase was significantly diminished by exposure to either 4 700 or 6 000 m simulated altitude.     

Evolution of the nucleotide sequence of influenza virus RNA segment 7 during drift of the H3N2 subtype

The complete genetic information contained in the influenza virus RNA segment 7 of the A/Bangkok/ $\text{1}\text{79}$ (H3N2) strain has been cloned by in vitro synthesis of the complementary dsDNA and its insertion into plasmid pBR322. The nucleotide sequence of the viral RNA segment has been determined from the cDNA insert. It is 1027 nucleotides long, and contains two open reading frames, as shown for other influenza virus strains. When compared with the previously published sequence for the A/Udorn/72 (H3N2) strain, 15 nucleotide exchanges are observed, most of them silent mutations, and only two causing amino acid changes in each of the M1 and M2 protein sequences.