Secretors

Hutson, A. M., Airaud, F., LePendu, J., Estes, M. K., and Atmar, R. L. (2005). Norwalk virus infection associates with secretor status genotyped from sera. /. Med. Virol. 77,116-120. 

Nordgren, J., Kindberg, E., Lindgren, P. E., Matussek, A., and Svensson, L. (2010). Norovirus gastroenteritis outbreak with a secretor-independent susceptibility pattern, Sweden. Emerg. Infect. Dis. 16, 81-87. 

Staphylococcus carnosus is genetically highly stable, a good secretor (Gram positive) able to translocate proteins containing several hydrophobic transmembrane regions [58], and it has no extracellular proteases, which makes it suitable for production of the secreted enzymes [58],... 

IgA is associated mainly with seromucous secretions such as saliva, tears, nasal fluids, etc., and is secreted as a dimer with both a J chain and a secretor piece (relative molecular mass 70 000), the latter apparently to prevent damage to the molecule by proteolytic enzymes. Its major role appears to be the protection of mucous membranes and its presence in blood, mainly as the monomer, may be as a result of absorption of the degraded dimer. 

The stroma-independent mutants belong to two different classes secretors and non secretors. The supernatants of the 89 mutants were tested for their ability to support stroma-independent growth of Myl-D7. Myl-D7 cells were plated at two concentrations (2.0x10 cells/mL and SxIO cells/mL) in triplicate in 24-well plates containing CM from confluent mutant cultures. 

For most of the supernatants tested the number of wild type Myl-D7 indicator cells decreased rapidly to less than 10% within the first 10 days. These mutants were classified as non secretors. Only 26 of the total 89 mutants secreted an activity stimulating the survivaFproliferation of Myl-D7 for at least two weeks. Furthermore, only ten of these secretor mutants (e.g. 6i-4, 6i-22) stimulated the growth of Myl-D7 for longer than 6 weeks (data not shown Heberlein et al, 2006). 

Figure 9. Some factor secreting mutants expresses CSF-1 transcripts. Northern blot analysis. 12mg of total RNA/lane were analyzed. The major transcript was a 4.0 kb CSF-1 message. Results for parental Myl D7 cells, stroma dependent subclones derived and stroma independent mutants are shown 1, 3i-l 2, 5i-l 3, 6i-4 4, 61-5 5, 31-2 6, 4i-l 7, 5i-3 8, 6i-2 9, 6i-3 10, 6i-17 11, 6i-18 12, 6i-19 13, 6i-20 14, 61-21 15, 6i-22 16, 6i-23 17, 6i-26. Those stroma independent mutants that are secretors are also indicated. Although additional CSF-1 specific splice variants could be detected at low levels in MS-5 and Myl-D7 mutants with high CSF-1 expression, no mutant/cell line specific splice product could be shown. However, the size of the splice product detected depended on the probe that was used for hybridization. Two additional messages (3.2 kb and 2.3 kb) were detected by hybridization with a full length CSF-1 cDNA and only one additional message (2.3kb) was detected by hybridization with a 3 fragment of the cDNA.

Low expression of a 4kb transcript was detected in uncloned cells of Myl-D7 and in all stroma-dependent subclones. Two types of secreting mutants were identified. About half of the secretors (7/16), expresses ectopically high levels of CSF-1 transcripts (e.g. 5i-l, 5i-3, 61-2, 61-3, 6i-4). The remainder of the secretors expressed low levels of CSF-1 transcripts, comparable to the very low level of CSF-1 message in wild type Myl-D7 (e.g. 6i-5, 61-21, 61-22, 61-26). 

The saliva of secretors has been used as a source of blood group substances in several investigations. Landsteiner obtained very active material from horse saliva and was able to show that it contained D-galac-tose and a hexosamine. More recently the same author compared the blood group substances from the saliva of individuals of groups A, B and 0 and found that there was very little difference in their properties (see Table III). 

The presence of one antigenic determinant may reduce the extent of expression of another. Thus, in an A glycoprotein of a secretor, the expression of the H determinant is largely inhibited, and by using enzymes (30) which destroy A or B activity, H activity is greatly increased (3, 7). Also, gene interactions may occur as, for example, when the H and Le genes are both present, a new specificity termed Leb arises... 

Concanavalin A was found by Clarke and Denborough (35) to precipitate with blood group glycoproteins from human gastric juice from two group O non-secretors and 2 group O and 3 group A secretors it... 

Besides addition of heme, the influence of culture temperature on heterologous production of peroxidases has also been reported. For example, lowering the culture temperature from 28 to 19°C enhanced the level of active versatile peroxidase of P. eryngii 5.8-fold and reduced the effective proteolytic activity of the A. nidulans host strain by 2-fold. In this way, a maximum peroxidase activity of 466 U/L was reached [42]. Efficient heterologous production of peroxidases is not always dependent on the availability of heme. The heterologous production of Arthromyces ramosus peroxidase (ARP) has been analyzed in A. awamori under the control of the inducible endoxylanase promoter. Secretion of active ARP was achieved at up to 800 mg/L in shake flask cultures without addition of hemin [43]. This represents a 1,600-fold increase in production compared to ARP production in S. cerevisiae and 38-fold increase compared to ARP production in P. pastoris (see Sect. 12.2). These observations support that several filamentous fungi are more effective secretors of proteins than yeast strains like S. cerevisiae and P. pastoris. Also for... 

Lima-bean lectin precipitated blood-group A and B secretor saliva, but not O it did not precipitate the saliva of any nonsecretors.2,3,103 Kriipe77 substantiated Boyd s results, using secretor saliva as an inhibitor of lima-bean lectin-erythrocyte agglutination. Types A,B, A,A2, AiO, and A20 saliva all inhibited the lima-bean lectin, whereas type OO saliva and type OO ovarian-cyst material were noninhibitory. 

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