Montmorillonite,Oligonucleotides, RNA and Origin of Life

Na-montmorillonite prepared from Volclay by the titration method facilitates the self-condensation of ImpA, the 5'-phosphorimidazolide derivative of adenosine. As was shown by AE-HPLC analysis and selective enzymatic hydrolysis of products, oligo(A)s formed in this reaction are 10 monomer units long and contain 67% 3',5'-phosphodiester bonds (Ferris and Ertem, 1992a). Under the same reaction conditions, 5'-phosphorimidazolide derivatives of cytidine, uridine and guanosine also undergo self-condensation producing oligomers containing up to 12-14 monomer units for oligo(C)s to 6 monomer units for oligo(G)s. In oligo(C)s and oligo(U)s, 75-80% of the monomers are linked by 2',5'-phosphodiester bonds. Hexamer and higher oligomers isolated from synthetic oligo(C)s formed by montmorillonite catalysis, which contain both 3',5'- and 2',5'-linkages, serve as catalysts for the non-enzymatic template directed synthesis of oligo(G)s from activated monomer 2-MeImpG, guanosine 5'-phospho-2-methylimidazolide (Ertem and Ferris, 1996). Pentamer and higher oligomers containing exclusively 2',5'-linkages, which were isolated from the synthetic oligo(C)s, also serve as templates and produce oligo(G)s with both 2',5'- and 3',5'-phosphodiester bonds. Kinetic studies on montmorillonite catalyzed elongation rates of oligomers using the computer program SIMFIT demonstrated that the rate constants for the formation of oligo(A)s increased in the order of 2-mer < 3-mer < 4-mer ... < 7-mer (Kawamura and Ferris, 1994). A decameric primer, dA(pdA)8pA bound to montmorillonite was elongated to contain up to 50 monomer units by daily addition of activated monomer ImpA to the reaction mixture (Ferris, Hill and Orgel, 1996). Analysis of dimer fractions formed in the montmorillonite catalyzed reaction of binary and quaternary mixtures of ImpA, ImpC, 2-MeImpG and ImpU suggested that only a limited number of oligomers could have formed on the primitive Earth rather than equal amounts of all possible isomers (Ertem and Ferris, 2000). Formation of phosphodiester bonds between mononucleotides by montmorillonite catalysis is a fascinating discovery, and a significant step forward in efforts to find out how the first RNA-like oligomers might have formed in the course of chemical evolution. However, as has been pointed out in several publications, these systems should be regarded as models rather than a literal representation of prebiotic chemistry (Orgel, 1998; Joyce and Orgel, 1999; Schwartz, 1999).     

Is there a special mechanism behind the changes in somatic cell and polymorphonuclear leukocyte counts,and composition of milk after a single prolonged milking interval in cows?

Background  

A single prolonged milking interval (PMI) e.g. after a technical stop in an automated milking system is of concern for the producer since it is associated with a short-lasting increase in milk somatic cell count (SCC), which is a major quality criterion used at the dairy plants. The content of polymorphonuclear leukocytes (PMN) and how the milk quality is influenced has not been much investigated. The SCC peak occurs without any obvious antigen challenge, possibly indicating a different leukocyte attraction mechanism after a PMI than we see during mastitis.     

No Effect of a Homeopathic Preparation on Neonatal Calf Diarrhoea in a Randomised Double-Blind,Placebo-Controlled Clinical Trial

A double-blind, placebo-controlled clinical trial of a homeopathic treatment of neonatal calf diarrhoea was performed using 44 calves in 12 dairy herds. Calves with spontaneously derived diarrhoea were treated with either the homeopathic remedy Podophyllum (D30) (n = 24) or a placebo (n = 20). No clinically or statistically significant difference between the 2 groups was demonstrated. Calves treated with Podophyllum had an average of 3.1 days of diarrhoea compared with 2.9 days for the placebo group. Depression, inappetence and fever were presented equally in the 2 groups. These results support the widely held opinion that scientific proof for the efficacy of veterinary homeopathy is lacking. In the European Union this implies a considerable risk for animal welfare, since in some countries priority is given to homeopathic treatments in organic farming.     

Dual hydrolysis model of the slowly biodegradable substrate in activated sludge systems

Experimental assessment of the hydrolysis rate coefficients for both domestic sewage and a number of industrial wastewaters was performed with emphasis on two different hydrolysis mechanisms associated with the readily and slowly hydrolyzable COD fractions. The adopted dual hydrolysis model was justified on the basis of significantly different rate constants. The hydrolysis rate of particulate COD occurred at such a slow rate that would significantly interfere with endogenous decay. © Rapid Science Ltd. 1998