Structural analysis of trisialylated biantennary glycans isolated from mouse serum transferrin: Characterization of the sequence Neu5Gc(α2-3)Gal(β1-3)[Neu5Gc(α2-6)]GlcNAc(β1-2)Man

Five variants of mouse serum transferrin (mTf, designated mTf-I to mTf-V) with respect to carbohydrate composition have been isolated by DEAE-cellulose chromatography in the following relative percentages: mTf-I: 0.55; mTf-II: 0.79; mTf-III: 71.80; mTf-VI: 21.90 and mTf-V: 4.96. The primary structures of the major glycans from mTf-III and mTf-IV were determined by methylation analysis and ¹H-nuclear magnetic resonance (NMR) spectroscopy. All glycans possessed a common trimannosyl-N,N′-diacetylchitobiose core. From the glycovariant mTf-III two isomers of a conventional biantennary N-acetyllactosamine type were isolated, in which two N-glycolylneuraminic acid (Neu5Gc) residues are linked to galactose either by a (α2-6) or (α2-3) linkage. A subpopulation of this glycovariant contains a fucose residue (α1-6)-linked to GlcNAc-1. The structure of the major glycan found in variant mTf-IV contained an additional Neu5Gc and possessed the following new type of linkage: Neu5Gc(α2-3)Gal(β1-3)[Neu5Gc(α2-6)]GlcNAc(β1-2)Man(α1-3). In addition to this glycan, a minor compound contained the same antennae linked to Man(α1-6). In fraction mTf-V, which was found to be very heterogeneous by ¹H NMR analysis, carbohydrate composition and methylation analysis suggested the presence of tri′-antennary glycans sialylated by Neu5Gc α-2,6- and α-2,3-linked to the terminal galactose residues. In summary, mTf glycans differed from those of other analyzed mammalian transferrins by the presence of Neu5Gc and by a Neu5Gc(α2-6)GlcNAc linkage in trisialylated biantennary structures, reflecting in mouse liver, a high activity of CMP-Neu5Ac hydroxylase and (α2-6)GlcNAc sialyltransferase.     

Mandibular fractures in short-finned pilot whales, Globicephala macrorhynchus

This study's objective was to investigate mandibular fractures in 50 short-finned pilot whales, Globicephala macrorhynchus, from two mass strandings. Based on current theories that this species is sexually dimorphic and polygynous, hypotheses were: (1) males should suffer more frequent or more substantial mandibular fractures than should females, and (2) fracture occurrence should increase with male reproductive maturity and potential correlates of maturity, such as age and length. Fractures were described and correlated with physical characteristics to infer possible explanations for injuries. Mandibular fractures were surprisingly common in males and females, being found in more than half of the animals examined (27/50, or 54% overall; 17/36 or 47% of females and 10/14 or 71% of males). Length was the only correlate of fracture presence; the proportion of animals showing evidence of fracture increased with length. These results offer some support to initial hypotheses, but there must be another set of consequences that contribute to mandibular fractures in females. A combination of intra- and interspecific interactions and life history characteristics may be responsible for fractures. Further research from a larger sample of this and other cetacean species are suggested to help elucidate both the causes and implications of mandibular fractures.     

Integrative recombination of Lactobacillus delbrueckii bacteriophage mv4: functional analysis of the reaction and structure of the attP site

The integrase of the temperate bacteriophage mv4 catalyzes site-specific recombination between the phage attP site and the attB site of the host during lysogenization of Lactobacillus delbrueckii subsp. bulgaricus. The mv4 integrase also functions in a wide variety of gram-positive bacteria and in Escherichia coli. In this report, in vitro and in vivo recombination assays were developed and the integrase was purified in order to study in greater detail the mv4 attP?×?attB recombination event. In a cell-free extract of E. coli at 42°?C, the mv4 integrase promotes efficient in vitro recombination between a supercoiled attP-containing plasmid and a linear attB fragment. The integrase, which was purified to apparent homogeneity, showed no absolute requirement for accessory factors, unlike the majority of the lambda Int family of recombinases. Deletion derivatives of the attP site were constructed and tested for recombination with the attB site in vitro. A 234-bp DNA fragment containing five scattered putative mv4 Int-binding sites was sufficient for function of the attP site. In contrast to the right arm of attP, most of the left arm could be deleted without drastically reducing the recombination efficiency. In vivo in E. coli, mv4 Int catalyzed recombination in trans between attP and attB sites present on two separate plasmids. This property was used to confirm in vivo the results of the deletion analysis of the attP site performed in vitro.     

Correspondence between effects of 5-azacytidine on SCE formation, cell cycling and DNA methylation in Chinese hamster cells

The effects of 5-azacytidine (5-Aza-C), alone and in combination with mitomycin C, were measured on sister-chromatid exchange (SCE) formation and DNA methylation in different genomic regions of Chinese hamster ovary cells and in Chinese hamster cells containing amplified, dihydrofolate reductase sequences and resistant to methotrexate. 5-Aza-C, when present for the penultimate preharvest cell cycle, induced SCEs in a manner consistent with a directly measured reduction in deoxycytosine methylation in cellular DNA. At higher 5-Aza-C concentrations, cell cycling was inhibited and both SCE induction and DNA demethylation tended to level off. Under appropriate conditions, 5-Aza-C also potentiated the induction of SCEs by mitomycin C. 5-Aza-C-induced DNA demethylation could also be detected in the vicinity of different DNA sequences with the use of comparative HpaII/MspI digestion, DNA blotting, and molecular probes. The efficiency of an individual demethylation event in inducing SCE induction appeared to be very low, compared with alkylating agents such as 8-methoxypsoralen, suggesting that SCE induction by 5-Aza-C might be an indirect effect from long range changes induced in cellular DNA or chromatin conformation.     

Calcium,magnesium, and phosphorus content of hair from two populations of rhesus monkeys

The use of hair for the assessment of human mineral nutritional status is controversial, yet has potential because of the ease of collection and storage, and the high concentration of minerals in hair. This study generated baseline values for hair macromineral content in the most commonly used primate model for human nutrition and disease, the rhesus monkey. Hair digests from monkeys in Maryland (n=98) and Puerto Rico (n=208) were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). Significant differences existed between the two populations for hair calcium (Ca), magnesium (Mg), and phosphorus (P) (P<0.01,P<0.001,P<0.02). Male hair had higher concentrations of Mg in specimens from the Puerto Rican population (P<0.001), whereas hair phosphorus was higher in female hair (P<0.02). There were no significant differences attributable to pregnancy status. Differences in hair content attributable to categorical age were found for Ca and Mg (P<0.001,P<0.01). Significant location differences paralleled dietary differences. These values therefore can be considered reference ranges for hair Ca, Mg, and P for free-ranging and caged rhesus monkeys. Preliminary reports of portions of these data were presented at the 69th Annual Meeting of the Federation of American Societies for Experimental Biology, April 1982, New Orleans, LA (B. M. Marriott, J. C. Smith, R. Jacobs, A. O. Jones, M. J. Kessler, and R. Rawlins,Fed. Proc. 41:770 [1982]) and in a symposium at the 6th Annual Meeting of the American Society of Primatologists, 1983, East Lansing, MI (B. Marriott, J. C. Smith, R. Jacobs, A. O. Lee Jones, R. Rawlins, and M. J. Kessler,Am. J. Primatol. 4(3):157 [1983]; B. Marriott, J. C. Smith, Jr., R. M. Jacobs, A. O. Lee Jones, R. Rawlins, and M. J. Kessler, inThe Cayo Santiago Macaques, R. Rawlins and M. J. Kessler, eds., SUNY Press, Albany, NY, pp. 219–231 [1986]).     

Effectiveness of antibiotics in preventing meningococcal disease after a case: systematic review

Objective To summarise the evidence for the role of antibiotics in preventing further cases of meningococcal disease through chemoprophylaxis given to the index patient, household contacts, and children in day care settings after a single case.Design Systematic review.Methods Studies were identified by searching Embase (1983-2003), Medline (1965-2003), and CAB Health (1973-2003) and by contacting the World Health Organization and the European meningococcal disease surveillance network and examining references of identified papers. The review included all studies with at least 10 cases in which outcomes were compared between treated and untreated groups.Main outcome measure Subsequent cases of meningococcal disease 1-30 days after onset of disease in the index patient.Results Four observational studies and one small trial met the inclusion criteria. Meta-analysis of studies on chemoprophylaxis given to household contacts showed a significant reduction in risk (risk ratio 0.11, 95% confidence interval 0.02 to 0.58). The number needed to treat to prevent a case was estimated as 218 (121 to 1135). Primary outcome data were not available in studies of chemoprophylaxis given to the index patient: when prophylaxis had not been given, rate of carriage after discharge from hospital was estimated as 3% (0 to 6), probably an underestimate of the true rate. No studies of chemoprophylaxis in day care settings were identified that met the inclusion criteria.Conclusion There have been no high quality experimental trials looking at control policies for meningococcal disease. The best available evidence is from retrospective studies. The risk of meningococcal disease in household contacts of a patient can be reduced by an estimated 89% if they take antibiotics known to eradicate meningococcal carriage. Chemoprophylaxis should be recommended for the index patient and all household contacts.     

Bacteriophage mv4 Site-Specific Recombination: the Central Role of the P2 mv4Int-Binding Site

The contributions of the five ^mv4Int- and two ^mv4Xis arm-binding sites to the spatial intasome organization of bacteriophage mv4 were found not to be equivalent. The 8-bp overlap region was mapped to the left extremity of the core region and is directly flanked by the P2 Int arm-binding site. These results and the absence of characteristic Int core-binding sites suggest that the P2 site is the determinant for integrase positioning and recognition of the core region.