Biomass and production of Argyrodiaptomus furcatus,a tropical calanoid copepod in Broa Reservoir,southern Brazil

The biomass and the production of Argyrodiaptomus furcatus (Sars), the most abundant copepod in Broa Reservoir (São Carlos, São Paulo State), were estimated, determining in the laboratory the development time and the quantity of organic carbon and establishing the relationship between these two parameters. The daily production was calculated from P = B(1- e^gt) and the annual production was obtained by integrating daily production against time. The maximum production of Argyrodiaptomus furcatus in the reservoir depends on the region considered and on the period of the year. The maximum production was 45.15 mg C m^–3d^–1 in March, 1976 at station II, region of macrophytes and 6.74 mg C m^–3d^–1 at station IV, near the dam. The mean production for the year is 6.26 mg C m^–3d^–1 at station II and 1.43 mg C m^–3d^–1 at station IV.     

Reaction of ethyl 2-amino-4,6-O-benzylidene-2-deoxy-d-gluconate with acetylenic esters

Ethyl 2-amino-4,6-O-benzylidene-2-deoxy-d-gluconate adds to acetylenic esters to give sugar enaminones. The following acetylene derivatives have been employed: methyl propiolate, ethyl phenylpropiolate, and dimethyl acetylenedicarboxylate (6). With compound 6, the reaction leads to a mixture of the expected enaminone and the isomeric oxazolidine derivative. The structures and configurations of the new compounds were studied by spectroscopic and chemical methods.     

Binding of 5-methoxypsoralen to human serum low density lipoproteins

5-methoxypsoralen (5-MOP) binds to human serum low density lipoproteins (LDL) according to a two-step process. Scatchard analysis of the first step yields K = 1.4 × 10⁵ M^?1 and 4 binding sites. It involves the LDL apoprotein. The second step corresponds to a solubilization, in the lipidic core, of ? 45 molecules of 5MOP per LDL molecule. It is accompanied by a large blue shift of the 5MOP fluorescence. The ability of LDL to bind 5MOP and to carry it into various cells may explain some biological effects sometimes encountered during PUVA therapy.     

Estimation of the mechanical parameters of the human respiratory system

A numerical algorithm has been developed for the estimation of the mechanical parameters of the human respiratory system. In order to estimate the pulmonary resistance and the dynamic pulmonary elastance, the transpulmonary pressure and the airflow at the mouth or nose are expanded in Chebyshev series. The nonlinear mathematical lung model and a set of measurements for airflow and pressure are then handled by the numerical technique. The lung model includes a component to account for turbulent flow in the larynx and trachea. This contribution presents an alternative method for lung parameter estimation and differs from most existing methods in that it does not need measurements for the tidal volume. It therefore eliminates the use of a body plethysmograph. The method may also find potential application to various other parameter identification problems.     

Germacranolides from Schkuhria anthemoidea

The isolation of eucannabinolide and three new sesquiterpene lactones from Schkuhria anthemoidea is reported. The structures and stereochemistries of the new compounds were established by chemical and spectroscopic means. The structure of santhemoidin B was confirmed by X-ray crystallography.     

Differential salt fractionation of active and inactive genomic domains in chicken erythrocyte

We have utilized the Sanders salt fractionation technique (Sanders, M. M. (1978) J. Cell Biol. 79, 97-109) to analyze the products of micrococcal nuclease digestion of adult chicken erythrocyte nuclei. By dot-blot hybridization with specific gene probes, it is found that nucleosomes from the globin gene domain, including a region extending to about 10 kilobase pairs 5' to the beta p gene are selectively enriched in the fractions eluted at low salt. In contrast, a single copy sequence located at about 10 kilobase pairs 5' to the beta p gene was concentrated in the less salt-soluble fractions. The vitellogenin and ovalbumin genes, which are never expressed in erythroid tissues, are also concentrated in the less salt-soluble fractions. Some more generally expressed genes (histone H4, thymidine kinase) appear to be more uniformly distributed. The low salt fractions are depleted in H1/H5, enriched in high mobility group 14 and 17, and contain somewhat more highly acetylated histones.     

Identification of two types of keratin polypeptides within the acidic cytokeratin subfamily I

Cytoskeletal filaments of the α-keratin type (cytokeratins) are a characteristic of epithelial cells. In diverse mammals (man, cow and rodents) these cytokeratins consist of a family of approximately 20 polypeptides, which may be divided into the more acidic (I) and the more basic (II) subfamilies. These two subfamilies show only limited amino acid sequence homology. In contrast, nucleic acid hybridization experiments and peptide maps have been interpreted to show that polypeptides of the same subfamily share extended sequence homology.We compare two polypeptides of the acidic cytokeratin subfamily, VIb (M_r 54,000) and VII (M_r 50,000), which are co-expressed in large amounts in bovine epidermal keratinocytes. These two epidermal keratins can be distinguished by specific antibodies and show different patterns of expression among several bovine tissues and cultured cells. In addition, they differ in the stability of their complexes with basic keratin polypeptides and in their tryptic peptide maps. The amino acid sequences deduced from the nucleotide sequences of complementary DNA clones containing the 3′ ends of the messenger RNAs for these keratins are compared with each other and with available amino acid sequences of human, murine and amphibian epidermal keratins. Bovine keratins VIb and VII share considerable sequence homology in the α-helical portion (68% residues identical) but lack significant homology in the extrahelical portion. Bovine keratin VIb shows, in its α-helical region, a pronounced sequence homology (88% identity) to the murine epidermal keratin of M_r 59,000. In addition, the non-helical carboxy-terminal regions of both proteins are glycinerich and contain a canonic sequence GGG^S_GYGG, which may be repeated several times. Moreover, their mRNAs present a highly conserved stretch of 236 nucleotides containing, in the murine sequence, the end of the coding and all of the non-coding region (81% identical nucleotides). Bovine keratin VII is considerably different from the murine M_r 59,000 keratin but is almost identical to the human cytokeratin number 14 of M_r 50,000, both in the α-helical and in the non-α-helical regions of the proteins, and the mRNAs of the human and the bovine keratins also display a high homology in their 3′ non-coding ends.The results show that in the same species keratins of the same subfamily can differ considerably, whereas equivalent keratin polypeptides of different species are readily identified by characteristic sequence homologies in the α-helical and the non-helical regions as well as in the 3′ non-coding portions of their mRNAs. Among the members of the acidic subfamily I of cytokeratin polypeptides that are co-expressed in bovine epidermis, at least two types can be distinguished by their carboxy-terminal sequences. One type is characterized by its abundance of glycine residues, a consensus GGG^S_GYGG heptapeptide sequence, which may be repeated several times, and an extended stretch of high RNA sequence homology in the 3′ non-coding part. The other type shows a predominance of serine and valine residues, a subterminal GGG^S_GYGG sequence (which has been maintained in Xenopus, cow and man) and also a high level of homology in the 3′ non-coding part of the mRNA. The data indicate that individual keratin type specificity overrides species diversity, both at the protein and the mRNA level. We discuss the evolutionary conservation and the tissue distribution of these two types of acidic keratin polypeptides as well as their possible biological functions.     

DQ α and β RFLP reveals the composition of the DQ molecule recognized by T-cell clones

Pst I RFLP, revealed with DQ and DQ probes, was compared with Taq I RFLP using a panel of DR-homozygous cell lines and HLA-typed family members. Taq I patterns, characteristic for each DR-associated DQ and allelic forms, were recognized in the homozygous state and then proven to segregate in the heterozygous members of informative families. The presence of both specific and chains was found to be necessary to form the type of DQ molecule specifically recognized by two alloreactive T-cell clones. Particular and associations also seem to be responsible for some Dw splits of the DRw6-positive cells. Taq I RFLP analysis may be more complex than the Pst I analysis, but is certainly more informative and complete, considering the type of information we were seeking by performing these types of experiments.Abbreviations used in this paper BSA bovine serum albumin - GLO glyoxalase - kb kilobase(s) - LCL lymphoblastoid cell line - MHC major histocompatibility complex - PBL peripheral blood lymphocyte - PLT primed lymphocyte test - RFLP restriction fragment length polymorphism - SDS sodium dodecyl sulfate - SSC standard sodium citrate - SSCP sodium, sodium citrate, sodium phosphate - TBE Tris-borate, boric acid, ethylenediaminetetraacetate (EDTA) - TCGF T-cell growth factor     

Isolation and structural studies on a galactofuranosyl-containing glycopeptide fromAscobolus furfuraceus

A galactofuranosyl-containing glycopeptide has been isolated from mycelium ofAscobolus furfuraceus by extraction with water. The glycoconjugate was purified by DEAE-cellulose chromatography followed by gel filtration. A molecular weight of about 20 000 was determined by the latter method using standard dextrans. Neutral sugars accounted for 94.5% of the glycopeptide and were characterized as mannose, galactose, and glucose. Glucosamine was estimated colorimetrically (1.8%). The molar ratio of Man:Gal:Glc:GlcNH₂ was 68:32:16:2. A trace amount of total phosphorus (0.2%) was found. The predominant amino acids were threonine and serine. The peptide moiety was labeled with [¹⁴C]formaldehyde and the elution of radioactivity was coincident with sugar on gel filtration in the presence of sodium dodecyl sulfate. The peak of radioactivity was retarded on release of galactose by mild acid hydrolysis. These results confirm the sugar-peptide linkage.