An anatomical study of anther development in Acorus L.: Phylogenetic implications

 Critical morphological synapomorphies have not been found in support of the Acoranan hypothesis, the molecular phylogenetic discovery that Acoranae are the basal monocots. The previously undetermined pattern of anther wall development in Acorus has been suggested to be one such character. Two main types of anther wall development have been recognized: 1) the “monocotyledonous” type, which characterizes both monocots and dicots, and 2) the “dicotyledonous” type, which is almost exclusively found among dicots. An anatomical study of anther wall development in Acorus was here undertaken using the electron microscope. Development of the anther wall in Acorus was found to be somewhat irregular or perhaps even intermediate between the two types although largely consistent with the “monocotyledonous” type. The presumed significance of anther wall development and other critical morphological characters to the Acoranan hypothesis in the absence of knowledge about the sister group to the monocots is evaluated. Received August 28, 2000 Accepted February 19, 2001     

Functional equivalence of the uridine turn and the hairpin as building blocks of tertiary structure in the Neurospora VS ribozyme.

Mutational, kinetic, and chemical modification experiments show that one of the three-way helical junctions in the Neurospora VS ribozyme contains a uridine turn that is important for organizing the functional three-dimensional structure of this junction. Disruption of the uridine turn disrupts the structure of the junction and decreases the self-cleavage activity of the ribozyme; however, substitution of the uridine turn with a variety of different hairpins, thereby transforming the three-way junction into a four-way junction, maintains catalytic activity. Chemical modification structure probing reveals that both the native junction and the hairpin-containing junction support the same tertiary interactions required elsewhere in the ribozyme for catalysis. These observations show that functionally equivalent three-dimensional RNA structures can be built from different secondary structure elements.     

An automated technique for monitoring carbon dioxide respired by insects*

ABSTRACT. A non-dispersive infrared gas analyser equipped with a Luft-type sonic detector and flow-through reference cell was automated to monitor the total volume of carbon dioxide (CO₂) respired by single insects or groups of insects. The infrared analyser was interfaced with an integrator for quantification, a microprocessor to control intermittent air flow through the insect respiration chambers, and a microcomputer for data storage and reduction. This technique has been used to monitor the CO₂ Output of diapausing and non-diapausing mature fifth instar larvae and of developing pupae of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). The resulting data were accurate, quantitative and reproducible.     

Inhibition of DNA synthesis in relation to enhanced survival of UV-damaged herpes virus in monkey cells treated by a variety of 2-nitronaphthofurans

Various 2-nitronaphthofuran derivatives (related to each other by simple structural modifications) were tested for 2 different effects in CV-1 monkey kidney cell cultures: the immediate inhibition of normal DNA synthesis and the capacity of pretreated cultures (40 h of contact) to support the replication of UV-damaged Herpes simplex virus (HSV). For all compounds tested, a fair correlation was found between their efficiencies to inhibit cellular DNA synthesis and to provoke an increase in UV-HSV production (virus reactivation). Virus reactivation was due to an increase in both the number of virus-producing cells and the amount of infectious particles produced per cell. The most efficient 2-nitronaphthofurans (particularly 2-nitro-7-methoxy-naphtho[2,1-b]furan-R 7000) were at least as potent as aflatoxin B1 in inducing virus reactivation.     

Amyloid fibrils derived from V-region together with C-region fragments from a lambda II-immunoglobulin light chain (HAR)

Amyloid fibril proteins were isolated from the spleen of a patient with IgD(lambda)-plasmocytoma by extraction and gel filtration in 5M guanidine hydrochloride. The molecular mass of the predominant polypeptide chain was approximately 5000 Da. Its complete amino-acid sequence was elucidated by stepwise automated degradation of the carboxymethylated polypeptide chain and by structural studies of tryptic and thermolysinolytic cleavage products. The length of the polypeptide chain was 58 to 59 residues and it was homologous to the amino acids in positions 8 through 65 of the variable part of an lambda-type immunoglobulin light chain, which was most closely related to the lambda II subgroup. The N-terminal sequence of this amyloid fibril protein proved to be heterogeneous, indicating cleavage after the amino acids in positions 7 and 8. Peptides from the constant part of the lambda-chain were unexpectedly found in the tryptic digest of the denatured amyloid protein HAR. One polypeptide derived from the constant region was separated from the main component by high performance liquid chromatography. Its amino-acid sequence commenced at position 111 and could be traced in 41 steps. In this case, at least two constant region fragments were shown to be constituents of the amyloid fibril protein. The association of fragments from the variable as well as the constant region is discussed with respect to amyloid formation.