β-decay,Bremsstrahlen, and the origin of molecular chirality

Summary A brief review is presented of the Vester-Ulbricht -decay Bremsstrahlen hypothesis for the origin of optical activity, and of subsequent experiments designed to test it. Certain of our experiments along these lines, begun in 1974 and involving the irradiation of racemic and optically active amino acids in a 61.7 KCi⁹⁰Sr–⁹⁰Y Bremsstrahlen source, have now been completed and are described. After 10.89 years of irradiation with a total Bremsstrahlen dose of 2.5×10⁹ rads, crystallinedl-leucine, norleucine, and norvaline suffered 47.2, 33.6, and 27.4% radiolysis, respectively, but showed no evidence whatsoever of asymmetric degradation.d- andl-Leucine underwent about 48% radiolysis and showed 2.4–2.9% radioracemization. Other samples in solution were too severely degraded to analyze. Probable intrinsic reasons for the failure of the Vester-Ulbricht mechanism to afford asymmetric radiolysis in the present and related experiments involving -decay Bremsstrahlen are enumerated.A portion of this material was presented at the 7th International Conference on the Origins of Life, Mainz, FRG, July 10–15, 1983     

AIDS as a zoonosis? Confusion over the origin of the virus and the origin of the epidemics

Based on findings demonstrating the simian ancestry of HIV, AIDS has been reported to be a zoonosis. However, this theory has never been proved and must seriously be questioned. Several arguments show that HIV-AIDS is not a zoonosis. (i) If AIDS were a zoonosis, there must be evidence of AIDS being directly acquired from an animal species, as is rabies, a disease that is directly acquired from animals. (ii) Despite long-term and frequent human exposure to SIV-infected monkeys in Africa, only 11 cross-species transmission events are known, and only four of these have resulted in significant human-to-human transmission, generating HIV-1 groups M and O and HIV-2 groups A and B. The closest relatives of SIVcpz (HIV-1 group N) and of SIVsm (HIV-2 groups C-H) are extremely rare, with only six HIV-1 group N-infected patients and only single individuals known to be infected by HIV-2 groups C-H. SIV, while capable of cross-species transmission, is thus poorly adapted for disease and epidemic spread. If AIDS were a zoonosis that is capable of significant human-to-human spread, there would be a plethora of founder subtypes and groups. (iii) Human exposure to SIV is thousands of years old, but AIDS emerged only in the 20th century. If AIDS were a zoonosis that spread into the human population, it would have spread to the West during slave trade. (iv) Experimental transmission of SIVs to different species of monkeys is often well controlled by the new host, showing that the virus and not the disease is transmitted. Therefore, we conclude that cross-species transmission of SIV does not in itself constitute the basis for a zoonosis. Transmission per se is not the major requirement for the generation of the AIDS epidemic. All HIVs do derive from simian species, but AIDS does not qualify as a zoonosis and this explanation cannot in itself account for the origin of AIDS epidemic. It is important to distinguish AIDS from true zoonoses (e.g. rabies) because research is needed to understand the processes by which animal viruses cause sustained human-to-human transmission, epidemics and even pandemics. Much is known about emerging viruses, but almost nothing is known about emerging viral diseases.     

Theβ-sheets of proteins,the biosynthetic relationships between amino acids,and the origin of the genetic code

Two forces are generally hypothesised as being responsible for conditioning the origin of the organization of the genetic code: the physicochemical properties of amino acids and their biosynthetic relationships (relationships between precursor and product amino acids). If we assume that the biosynthetic relationships between amino acids were fundamental in defining the genetic code, then it is reasonable to expect that the distribution of physicochemical properties among the amino acids in precursor-product relationships cannot be random but must, rather, be affected by some selective constraints imposed by the structure of primitive proteins. Analysis shows that measurements representing the size of amino acids, e.g. bulkiness, are specifically associated to the pairs of amino acids in precursor-product relationships. However, the size of amino acids cannot have been selected per se but, rather, because it reflects the-sheets of proteins which are, therefore, identified as the main adaptive theme promoting the origin of genetic code organization. Whereas there are no traces of the-helix in the genetic code table.The above considerations make it necessary to re-examine the relationship linking the hydrophilicity of the dinucleoside monophosphates of anticodons and the polarity and bulkiness of amino acids. It can be concluded that this relationship seems to be meaningful only between the hydrophilicity of anticodons and the polarity of amino acids. The latter relationship is supposed to have been operative on hairpin structures, ancestors of the tRNA molecule. Moreover, it is on these very structures that the biosynthetic links between precursor and product amino acids might have been achieved, and the interaction between the hydrophilicity of anticodons and the polarity of amino acids might have had a role in the concession of codons (anticodons) from precursors to products.     

What are the 'Calcichordata'? and the larger question of the origin of Ghordates

Argument around the question of the validity of the 'Calcichordata' emphasizes the need for a more functional and utilitarian view of the origin of the chordates. The calcichordate question is reviewed and 'tested' in terms of our usual ideas of biological reality. The concept is rejected and the Stylophora are viewed as aberrant and still largely unknown echinoderms. Rejection of the calcichordate concept turns us once more to the question of the origin of the chordates. A number of competing hypotheses are compared: the tunicate, dipleuruloid and archicoelomate models. The conclusion is that the dipleuruloid, a simple metazoan, offers the least explanatory difficulties. Also it is concluded that discussion of such a subject as this refines and improves our thinking concerning it.     

Origin of the chordate central nervous system – and the origin of chordates

 Contrary to traditional views, molecular evidence indicates that the protostomian ventral nerve cord plus apical brain is homologous with the vertebrates’ dorsal spinal cord plus brain. The origin of the protostomian central nervous system from a larval apical organ plus longitudinal areas along the fused blastopore lips has been documented in many species. The origin of the chordate central nervous system is more enigmatic. About a century ago, Garstang proposed that the ciliary band of a dipleurula-type larva resembling an echinoderm larva should have moved dorsally and fused to form the neural tube of the ancestral chordate. This idea is in contrast to a number of morphological observations, and it is here proposed that the neural tube evolved through lateral fusion of a ventral, postoral loop of the ciliary band in a dipleurula larva; the stomodaeum should move from the ventral side via the anterior end to the dorsal side, which faces the substratum in cephalo- chordates and vertebrates. This is in accordance with the embryological observations and with the molecular data on the dorsoventral orientation. The molecular observations further indicate that the anterior part of the insect brain is homologous with the anterior parts of the vertebrate brain. This leads to the hypothesis that the two organs evolved from the same area in the latest common bilaterian ancestor, just anterior to the blastopore, with the protostome brain developing from the anterior rim of the blastopore (i.e. in front of the protostome mouth) and the chordate brain from an area in front of the blastopore, but behind the mouth (i.e. behind the deuterostome mouth). Received: 28 August 1998 / Accepted: 14 November 1998     

Cellular origin and distribution of transforming growth factor-β1 in the normal rat myocardium

Summary Transforming growth factor- (TGF-) is a biologically active polypeptide present in normal tissues as well as transformed cells. Two structurally related forms of this peptide are TGF- ₁ and TGF- ₂. Using freshly isolated cardiomyocytes and non-myocyte heart cells, and a [³²P]-labelled cDNA probe to human TGF- ₁, we demonstrated that mRNA for TGF- ₁ could be detected only in the nonmyocyte fraction of heart cells. In the present study, the distribution of TGF- ₁ in the heart was determined by immunofluorescence staining by use of a polyclonal antibody to porcine TGF- ₁ in cryostat sections of rat heart. Immunofluorescence staining was intense around the blood vessels and radially diffuse in the surrounding myocardium.     

Chailakhyan’s views of the origin of consciousness and mentality

L.M. Chailakhyan’s views of sources of the origin of consciousness and mentality have been analyzed. It is supposed that the information interaction alone is not sufficient for the occurrence of consciousness. Something else is necessary that distinguishes a live system from lifeless and can be transmitted to the progeny and evolve. It is assumed that this something is an “information-physical interaction,” namely, an energy profile of conformational reorganizations of proteins during their interaction. Chailakhyan proves the point of view that this profile during the interaction of proteins cannot be calculated and therefore cannot be cognized. This conclusion is supported by Gödel’s incompleteness theorem.

     

The discovery of aniline and the origin of the term “aniline dye”

An historical background is provided for the term, “aniline dye,” which is still widely used as a synonym for “synthetic dye.” The discovery of aniline and the role of Hofmann in clarifying it are described. The subsequent discovery of mauveine (mauve) by a student of Hofmann's, William Perkin, and his difficulties in transforming an academic synthesis into a commercial product also are discussed. The key role of Scottish dyers, the Pullars of Perth and Thomas Keith in London, in this technology transfer is described. The subsequent ascendancy of the German dyestuff industry over British manufacturers is noted.     

The action of rennin on χ-casein the heterogeneity and origin of the insoluble products

• 1.1. The insoluble material formed by the action of rennin (EC_3·4·4·3) on χ-casein (and its derivatives) consists of two discrete components, or para-derivatives.
• 2.2. Variation of the pH, temperature and composition of the reaction mixture fails to produce an alteration in the relative amounts of these two products. They are evidently formed independently of one another and represent primary products of rennin action.
• 3.3. O-(Diethylaminoethyl)-cellulose chromatography of S-carboxymethyl-χ-caseins obtained from individual cows establishes the existence of two types of component in each genetic variant series which give rise separately to the major and minor para-derivatives. This result is consistent with an attack by rennin at only one position in each χ-casein molecule.

     

Dorso-ventral limb polarity and origin of the ridge: On the fringe of independence?

Molecular and developmental studies of limb pattern formation have recently gained widespread attention. The fact that vertebrate limbs are amenable to both genetic and embryological manipulations has established this model system as a valuable paradigm for studying vertebrate development. Limb buds are polarised along all three major axes and the establishment of the dorso-ventral (DV) polarity is dependent upon cues localised in the trunk, where a DV ectodermal interface is produced by confrontation of dorsal and ventral identities. By analogy to Drosophila imaginal disc development, this interface has been proposed to determine and position an ectodermal organising centre, the Apical Ectodermal Ridge (AER), controlling limb bud outgrowth. Recent fate mapping studies⁽¹⁾ and studies of genes regulating DV limb polarity^(2-6), AER formation^(7,8) and differentiation⁽⁹⁾ suggest, however, that DV patterning and AER induction, though coordinately regulated during limb bud outgrowth, may early on be more dissociated than expected.     

Evolutionary origin of the class A and class C β-lactamases

Summary The protein sequences of 18 class A -lactamases and 2 class C -lactamases were analyzed to produce a rooted phylogenetic tree using the DD peptidase of Streptomyces R61 as an outgroup. This tree supports the penicillin-binding proteins as the most likely candidate for the ancestoral origin of the class A and class C -lactamases, these proteins diverging from a common evolutionary origin close to the DD peptidase. The actinomycetes are clearly shown as the origin of the class A -lactamases found in other non-actinomycete species. The tree also divides the -lactamases from the Streptomyces into two subgroups. One subgroup is closer to the DD peptidase root. The other Streptomyces subgroup shares a common branch point with the rest of the class A -lactamases, showing this subgroup as the origin of the non-actinomycete class A -lactamases. The non-actinomycete class A -lactamase phylogenetic tree suggests a spread of these -lactamases by horizontal transfer from the Streptomyces into the non-actinomycete gram-positive bacteria and thence into the gram-negative bacteria. The phylogenetic tree of the Streptomyces class A -lactamases supports the possibility that horizontal transfer of class A -lactamases occurred within the Streptomyces.     

Radiochemical purity of β-sitosterols tritiated by catalytic exchange and by the Wilzbach procedure

• 1.1. Tritiation of commercial β-sitosterol by the Wilzbach procedure resulted in partial reduction (10%) of the double bond of this sterol. The dihydrositosterol contained 60% of the total H³ of the tritiated sample.
• 2.2. Tritiation of β-sitosterol by catalytic exchange resulted in negligible reduction of the double bond.
• 3.3. The epoxide derivatives of β-sitosterol, which are easily prepared, are useful in establishing the radiochemical purity of tritiated β-sitsoterol.
• 4.4. The α, β, and 1:1 (α + β) molecular complex of sitosterol epoxide acetates were separated and characterized.
• 5.5. Three commercial, unlabeled samples of β-sitosterol were found to contain from 4 to 14% dihydrositosterol (β-sitostanol).
     

The origin of life and the left-handed amino-acid excess: the furthest heavens and the deepest seas?

The origin of life is an extraordinary problem that leads back to the structure and dynamics of the cosmos and early development of organic molecules. Within that wider question lies an unsolved problem that has troubled biologists for 150 years. What is the origin of the dominant presence of left-handed stereoisomers of amino acids in nature even though their synthesis normally results in an equal mixture of the right- and left-handed molecular forms? We propose that asymmetric Earth rotation caused at dawn and dusk circularly polarized UV light (CPUVL) of opposite polarity and reversed temperature profiles in the oceans. Destruction of the d-isomer by CPUVL at dusk in a sea surface hotter than at dawn created a daily l-isomer excess protected from radiation by nightfall, preserved by down-flow (diffusive, mechanical) into cold, darker regions, eventually initiating an l-amino-acid excess embodied in early marine forms. Innumerable mechanisms have been proposed for the origin of l-chiral dominance in amino acids and none proven. Since the thalidomide tragedy, homochirality of amino acids has been a growing practical issue for medicine. Understanding its origin may bring further and unexpected benefits. It may also be a modest pointer to the possibility of positive answers to whether intelligent life will have the capacity to continue to protect itself from conditions inimical to survival.     

Isozyme evidence of the parental origin and possible fertility of the hybrid Potamogeton×fluitans Roth

 The hybrid Potamogeton×fluitans Roth is thought to have resulted from hybridization between P. lucens L. and P. natans L. This hybrid has only been recorded at a few locations in the British Isles. At most of these sites the number of individuals found have been quite low. The one exception to this being a population in the Moors River, Dorset and South Hampshire, England, where a substantially larger population exists. Using seven different enzyme systems, this study provided support for the putative parental origin of this hybrid. In addition, the population in the Moors River was shown to contain numerous multi-locus phenotypes suggesting that these individuals may be partially fertile and may backcross to one of its parental species, or alternatively undergo selfing or crossing to produce an F₂ generation. Received December 1, 2000 Accepted June 20, 2001