Abiotic model of photophosphorylation of ADP to ATP: Characteristics of photoreceptor pigments and the role of organosilicate matrix

A model of photophosphorylation of ADP to ATP under UV and blue light with the use of substances available in the prebiotic period of evolution is proposed. It is shown that the photoactive pigments of flavin and pterin nature formed along with polyamino acids during thermal synthesis of “proteinoids” from a mixture of amino acids initiate the process of photophosphorylation of ADP to ATP. Photophosphorylation occurs on proteinoid-silicate matrices of two types: (1) in the microspheres formed of proteinoids in the presence of polysilicic acid and (2) on the matrices obtained by adsorption of proteinoids on silicate particles.     

Photosensitivity of 8BrcGMP-induced conductance in ROS-excised patches.

Inside-out patches from ROS plasma membranes contain the basic enzymes of the phototransduction cascade. Similar to a native photoreceptor cell, such patches are capable of responding to light, the effect of which suppresses the cGMP-activated current. Photoresponses are observed only in the presence of GTP, whereas ATP essentially accelerates the current recovery to a dark level. Photoresponses are also observed in the presence of 8BrcGMP. Phosphodiesterase (PDE) hydrolyzes 8BrcGMP two orders of magnitude slower than cGMP, so the light inhibition of the 8BrcGMP-induced current cannot be accounted for by PDE activation. It seems that activity of cGMP-gated channels depends not only on cGMP concentration, but is additionally controlled by some other regulatory mechanisms.     

A tissue-specific puff (Balbiani ring a) in Chironomus thummi may contain a gene encoding a 67-kDa protein which exhibits non-tissue-specific expression

A 2.3-kb genomic clone has been isolated from the region where the tissue-specific puff, Balbiani ring a (BRa), is found on chromosome IV of the special lobe of Chironomus thummi salivary gland cells. The clone was characterized by nucleotide sequence analysis. Two clusters of direct tandem repeats were identified, as well as large and small open reading frames (ORFs). The large ORF was fused to an Escherichia coli lacZ gene. Antibodies against the beta-galactosidase/ORF fusion protein reacted selectively on Western blots with a 67-kDa protein. Western-blot analysis and immunoelectron microscopy showed that this protein was distributed in the cells of all larval tissues examined. We concluded that BRa, a tissue-specific puff, whose activity correlates with the synthesis of 160-kDa secretory protein [Kolesnikov et al., Chromosoma 83 (1981) 661-677], may also contain a gene which is not expressed in a tissue-specific manner.