Nesting,eggs and larvae of triggerfishes (Balistidae)

Synopsis Triggerfishes construct nests by excavating depressions in sand. Eggs are laid in an adhesive mass and anchored with rubble. A photograph of a newly-hatched embryo is included.     

Selective high-performance liquid chromatographic assays for hydralazine and its metabolites in plasma of man

Selective high-performance liquid chromatographic assays for hydralazine (I), hydralazine pyruvic acid hydrazone (II) and the acetylation metabolites, namely s-triazolo[3,4-a]-phthalazine (V) and 3-hydroxymethyl (VI) and 3-methyl-s-triazolo[3,4-a]phthalazine (VII) in human plasma were developed. Utilizing the fluorescence of these compounds or their derivatives the limits of detection could be extended down to 5 nmole/l (1 ng/ml) for I, 1 nmole/l (0.2 ng/ml) for II and 0.5 nmole/l (0.1 ng/ml) for V–VII. The intra-assay coefficients of variation for the assays ranged from 2 to 7% over the concentration range 5.0 to 0.05 μmole/l and the inter-assay variability in the slope of the standard curves ranged from 4 to 8%. An improved method for measuring the sum of I plus all its hydrazones (apparent I) was also developed. On addition of I to fresh plasma at 37°, half the added I was converted to II within 15 min and there was no detectable level of I, 2 h after the addition. The plasma level—time course of I, and its metabolites in a healthy volunteer (slow acetylator) following separate oral and intravenous administrations of I indicated that I contributed only a small fraction (4.3 and 4.7% respectively) to the area under the plasma level—time curve of apparent hydralazine.     

Toward a molecular paleontology of primate genomes

Families of related, but nonidentical repetitive DNA sequences, termed the alphoid DNAs, have been identified and characterized in representative species from seven major primate Families. The sequences appear as old as the primate Order itself: they are found in a prosimian (lemur), in a New World monkey, and in all Old World primates examined, including man. The alphoid DNAs are uniquely primate sequences and they may represent the most abundant repetitive DNAs in the primate genome. — A classification scheme for two major families of alphoid DNAs is proposed that is based upon restriction enzyme analysis and Southern blotting with radioactive probes prepared from component DNA (Maio, 1971) and from the human EcoRI dimer sequences (Manuelidis, 1976). The family of alphoid DNAs that hybridizes readily with component is termed the HindIII family of alphoid DNAs. This family shows an almost universal distribution among present-day primates. The family of DNA sequences that hybridizes readily with the human EcoRI dimer probe is termed the EcoRI dimer family of alphoid DNAs. This family may be restricted to the great apes and man. The two probes permitted the discrimination of different, but related alphoid families in present-day primates. Multiple alphoid sequence families are found within the genomes of individual primates and the major primate taxa can be characterized by the representations of the various alphoid DNAs within their genomes. — An Appendix is presented (Brown et al., 1981) indicating that competition hybridization effects may influence the autoradiographic banding patterns, and hence, the interpretations of Southern filter-transfer hybridizations when dealing with related repetitive sequences such as the alphoid DNAs that are present in abundance in eukaryotic genomes.     

Transformation of Saccharomyces cerevisiae with yeast mitochondrial DNA linked to two micron circular yeast plasmid

Mitochondrial DNA from a petite mutant of yeast carrying an oligomycin resistance determinant has been ligated in vitro to 2 μm yeast plasmid DNA. The recombinant DNA so produced has been used to transform an oligomycin sensitive strain of Saccharomyces cerevisiae to oligomycin resistance at a frequency approaching 50 times the spontaneous mutation rate to oligomycin resistance. The majority of transformants showed genetic properties suggesting that recombination between the transforming DNA and the resident mtDNA has occurred. The properties of a subclass of oligomycin resistance transformants suggested that in these cells the transforming DNA has not become stably integrated into the mitochondrial genome of the recipient cell.     

The terminal structures of feather keratin mRNA

Terminal labeling of embryonic feather keratin mRNA with [³H]KBH₄ followed by digestion with ribonuclease T₁ and T₂, alkaline phosphatase, snake venom phosphodiesterase, and nucleotide pyrophosphatase and analysis of the products by high voltage paper electrophoresis, indicated the presence of the sequence m⁷G(5)ppp(5)N at the 5-end of the mRNA. Ribonuclease T₁ and A digests of the terminally labeled, and also of unlabeled mRNA followed by fractionation on denaturing polyacrylamide gels indicated the presence of polyadenylate tracts ranging in size from 45 to 165 nucleotides at the 3-end of the mRNA.     

Poly(A+)mRNA sequences in free mRNP and polysomes of mouse ascites cells

The poly(A⁺)RNA of the free mRNP of mouse Taper ascites cell contains a very reduced number of different mRNA sequences compared to the polysome poly(A⁺)RNA. By the technique of mRNA:cDNA hybridization we have determined that the free mRNP contains approximately 400 different mRNA sequences while the polysomes contain about 9000 different mRNAs. The free mRNP poly(A⁺)RNA sequences are present in two abundance classes, the abundant free mRNP class containing 15 different mRNA sequences and the less abundant free mRNP class containing 400 different mRNAs. The polysome poly(A⁺)RNA consists of three abundance classes of 25, 500 and 8500 different mRNA sequences.Despite its intracellular location in RNP structures not directly involved in protein synthesis the poly(A⁺)RNA purified from the free RNP of these cells was a very effective template for protein synthesis in cell-free systems. Cell-free translation products of free mRNP and polysome poly(A⁺)RNAs were analyzed by two-dimensional gel electrophoresis. This analysis confirmed the hybridization result that the free mRNP poly(A⁺)RNA contained fewer sequences than polysomal poly(A⁺)RNA. The abundant free RNP-mRNA directed protein products were a subset of the polysome mRNA-directed protein products. The numbers of more abundant products of cell-free protein synthesis directed by the free RNP-mRNA and polysomal mRNA were in general agreement with the hybridization estimates of the number of sequences in the abundant classes of these two mRNA populations.     

Halogenated monoterpenes of the red alga Microcladia

The red marine algae Microcladia borealis, M. californica and M. coulteri produce several unusual halogenated monoterpenes including violacene, plocamene-B, plocamene-C, and plocamane-D. The isolation of these terpenes along with a study of their variation in each Microcladia at different locations are described.     

Biogenesis of mitochondria

Summary The action of ethidium bromide and berenil on the mitochondrial genome of Saccharomyces cerevisiae has been compared in three types of study: (i) early kinetics (up to 4 h) of petite induction by the drugs in the presence or absence of sodium dodecyl sulphate; (ii) genetic consequences of long-term (8 cell generations) exposure to the drugs; (iii) inhibition of mitochondrial DNA replication, both in whole cells and in isolated mitochondria.The results have been interpreted as follows. Firstly, the early events in petite induction differ markedly for the two drugs, as indicated by differences in the short-term kinetics. After some stage a common pathway is apparently followed because the composition of the population of petite cells induced after long-term exposure are very similar for both ethidium bromide and berenil. Secondly, both drugs probably act at the same site to inhibit mitochondrial DNA replication, in view of the fact that a petite strain known to be resistant to ethidium bromide inhibition of mitochondrial DNA replication was found to have simultaneously acquired resistance to berenil. From consideration of the drug concentrations needed to inhibit mitochondrial DNA replication in vivo and in vitro it is suggested that in vivo permeability barriers impede the access of ethidium bromide to the site of inhibition of mitochondrial DNA replication, whilst access of berenil to this site is facilitated. The site at which the drugs act to inhibit mitochondrial DNA replication may be different from the site(s) involved in early petite induction. Binding of the drugs at the latter site(s) is considered to initiate a series of events leading to the fragmentation of yeast mitochondrial DNA and petite induction.