Development of eggs,larvae and pelagic juveniles of three Indo-Pacific ostraeiid fishes (Tetraodontiformes):Ostracion meleagris,Lactoria fornasini andL. diaphana

The eggs, larvae and pelagic juveniles ofOstracion meleagris, Lactoria fornasini andLactoria diaphana were identified from reared and field collected specimens from Hawaii, Japan, Australia and the eastern Pacific. Eggs are large and pelagic with limited chorion ornamentation and a cluster of oil droplets. At hatching, larvae are well developed, rotund, and enclosed in a dermal sac. The sac disappears and dermal plates form prior to notochord flexion. Larvae of the three species can be distinguished by their pigment patterns and development of the carapace of ossified dermal plates. Eggs of the three species could not be distinguished. The larval stage ends at a small size (< 6 mm) but the juveniles may grow to a substantial size while remaining pelagic.L. diaphana matures and spawns while pelagic in the eastern Pacific.     

Separation of multiple isomers of inositol phosphates formed in GH3 cells.

A high-performance-liquid-chromatography (h.p.l.c.) separation was developed, which resolves isomers of inositol monophosphate (IP), inositol bisphosphate (IP2), and inositol trisphosphate (IP3) in a single run. In GH3 cells labelled with [3H]inositol, treated with Li+ and thyrotropin-releasing hormone (TRH), radiolabelled components identified as inositol 1-phosphate (I1P), inositol 2-phosphate (I2P), inositol 4-phosphate (I4P), inositol 1,4-bisphosphate [I(1,4)P2], inositol 1,3,4-trisphosphate [I(1,3,4)P3] and inositol 1,4,5-trisphosphate [I(1,4,5)P3] are present, as are multiple unidentified IP2 peaks. After TRH stimulation, both I1P and I4P increase, the increase in I4P preceding that of I1P; I(1,4)P2 and an unknown IP2 increase; and both I(1,3,4)P3 and I(1,4,5)P3 increase, the increase in I(1,4,5)P3 being rapid and transient, whereas the increase in I(1,3,4)P3 is slower and more sustained. The most rapidly appearing inositol phosphates produced after TRH stimulation are I(1,4)P2 and I(1,4,5)P3.     

Plasmid expression and maintenance during long-term starvation-survival of bacteria in well water.

Strains of enteric bacteria and pseudomonads containing plasmid R388::Tnl721 (Tpr, Tcr) or pRO101 (Hgr, Tcr) were starved for over 250 days in sterile well water to evaluate effects of starvation-survival on plasmid expression and maintenance. Viable populations dropped to between approximately 0.1 and 1% of the initial populations. Escherichia coli(pRO101) and Pseudomonas cepacia(pRO101) lost both viability and plasmid expression at a lower rate than strains containing R388::Tnl721. Three patterns of host-plasmid interaction were detected: (i) no apparent loss of plasmid expression, (ii) loss of plasmid expression on initial recovery with subsequent expression upon resuscitation, and (iii) loss of capability to produce functional plasmid resistance.     

Effect of Growth Rate and Starvation-Survival on the Viability and Stability of a Psychrophilic Marine Bacterium

Cell populations of the marine bacterium ANT-300, from either batch or continuous culture with dilution rates ranging from D = 0.015 h⁻¹ to D = 0.200 h⁻¹, were monitored for viability, direct counts, and optical density for 98 days under starvation conditions. Three stages of starvation survival were observed for each of the cell populations. Although direct counts remained at 2 × 10⁷ to 3 × 10⁷ cells ml⁻¹ throughout the starvation period, large fluctuations occurred in cell viability during stage 1 (0 to 14 days) of starvation survival. Stage 2 (14 to 70 days) involved an overall decrease in viability for each of the cell populations; the rate of viability loss was dependent upon the growth rate. Cell viability stabilized at approximately 0.3% of the direct count in stage 3 (70 to 98 days). Long-term starvation corresponded to the prolongation of stage 3 starvation survival. Cell volumes for each of the cell populations decreased with the length of the starvation period. However, the cell volume of starved cells was also dependent more on growth rate than on the length of the time starved. We hypothesize that the cell population with the slowest growth rate is most closely representative of cells found in the oligotrophic marine environment.     

Pathogenesis-related protein 4 is structurally homologous to the carboxy-terminal domains of hevein, Win-1 and Win-2

Summary The extracellular, acidic pathogenesis-related protein, PR-4, was purified to homogeneity from leaves of Nicotiana tabacum infected with tobacco mosaic virus (TMV) and characterized by partial amino acid sequencing. Complementary DNA clones encoding PR-4 were isolated using an oligonucleotide probe based on the sequence of one of the peptides. The deduced PR-4 protein sequence was found to be related to a family of proteins including hevein and Win-1, which have an amino-terminal lectin domain and a carboxy-terminal domain of unknown function. PR-4 is homologous to the carboxy-terminus of these proteins but does not contain the lectin domain. Thus, the organization of the PR-4 family of proteins is similar to that of the plant chitinase family, in that both contain structural subclasses characterized by the presence or absence of an amino-terminal lectin domain. This observation is consistent with the proposal that the DNA encoding the lectin domain may be capable of transposing to form new genes encoding proteins of more complex, multi-domain structure. The expression of PR-4 mRNA was found to increase dramatically in response to TMV infection and the time course of RNA accumulation was similar to that of other PR proteins.     

Intracellular location of rabbit poxvirus nucleic acid within infected cells as determined by in situ hybridization.

The intracellular location of rabbit poxvirus DNA within cells during the course of infection has been determined by the hybridization in situ of labeled viral DNA probes to uninfected and infected cells under various conditions. Extensive control experiments were performed to demonstrate that DNA could be detected selectively and accurately within the cell. Our results suggest that rabbit poxvirus DNA is located only within the cytoplasm during the reproductive cycle, and we found no evidence that viral DNA enters the cell nucleus. The pattern of hybridization of viral DNA at early times (1 and 2 h postinfection) and in the presence of inhibitors of viral DNA synthesis suggests that there may be an association between the input viral DNA and some structural component of the host cell. A number of observations support the hypothesis that the host cell nucleus is required for a productive poxvirus infection. Our results are discussed in terms of the possible role of the nucleus in the replication of poxviruses.     

Compartmentation of intracellular nucleotides in mammalian cells

The important role of nucleotides in cellular metabolism requires that serious consideration be given to the question of the homogeneity or inhomogeneity of nucleotide pools in cells. The purpose of this review is to summarize the existing evidence for compartmentation of nucleotide pools, discuss the limitations of this evidence, and to discuss the implications of compartmentation for the interpretation of nucleotide concentration measurements. Evidence for nucleotide compartmentation comes from the following types of evidence: compartmentation of RNA precursors; compartmentation of deoxynucleoside triphosphates; mitochondrial compartmentation; the existence of tightly bound nucleotides; pools derived from alternative synthetic routes; compartmentation in cyclic nucleotide metabolism; channeling in the synthesis of pyrimidine nucleotides; and others. The types of evidence adduced for compartmentation will be considered critically and in detail, and alternative explanations considered, as well. Implications of the data and hypotheses on nucleotide compartmentation for the interpretation of nucleotide pool measurements in various types of experiments will be discussed.     

A comparative description of mitochondrial DNA differentiation in selected avian and other vertebrate genera

Levels of mitochondrial DNA (mtDNA) sequence divergence between species within each of several avian (Anas, Aythya, Dendroica, Melospiza, and Zonotrichia) and nonavian (Lepomis and Hyla) vertebrate genera were compared. An analysis of digestion profiles generated by 13-18 restriction endonucleases indicates little overlap in magnitude of mtDNA divergence for the avian versus nonavian taxa examined. In 55 interspecific comparisons among the avian congeners, the fraction of identical fragment lengths (F) ranged from 0.26 to 0.96 (F = 0.46), and, given certain assumptions, these translate into estimates of nucleotide sequence divergence (p) ranging from 0.007 to 0.088; in 46 comparisons among the fish and amphibian congeners, F values ranged from 0.00 to 0.36 (F = 0.09), yielding estimates of P greater than 0.070. The small mtDNA distances among avian congeners are associated with protein-electrophoretic distances (D values) less than approximately 0.2, while the mtDNA distances among assayed fish and amphibian congeners are associated with D values usually greater than 0.4. Since the conservative pattern of protein differentiation previously reported for many avian versus nonavian taxa now appears to be paralleled by a conservative pattern of mtDNA divergence, it seems increasingly likely that many avian species have shared more recent common ancestors than have their nonavian taxonomic counterparts. However, estimates of avian divergence times derived from mtDNA- and protein-calibrated clocks cannot readily be reconciled with some published dates based on limited fossil remains. If the earlier paleontological interpretations are valid, then protein and mtDNA evolution must be somewhat decelerated in birds. The empirical and conceptual issues raised by these findings are highly analogous to those in the long-standing debate about rates of molecular evolution and times of separation of ancestral hominids from African apes.      

Methods for computing the standard errors of branching points in an evolutionary tree and their application to molecular data from humans and apes

Statistical methods for computing the standard errors of the branching points of an evolutionary tree are developed. These methods are for the unweighted pair-group method-determined (UPGMA) trees reconstructed from molecular data such as amino acid sequences, nucleotide sequences, restriction-sites data, and electrophoretic distances. They were applied to data for the human, chimpanzee, gorilla, orangutan, and gibbon species. Among the four different sets of data used, DNA sequences for an 895-nucleotide segment of mitochondrial DNA (Brown et al. 1982) gave the most reliable tree, whereas electrophoretic data (Bruce and Ayala 1979) gave the least reliable one. The DNA sequence data suggested that the chimpanzee is the closest and that the gorilla is the next closest to the human species. The orangutan and gibbon are more distantly related to man than is the gorilla. This topology of the tree is in agreement with that for the tree obtained from chromosomal studies and DNA-hybridization experiments. However, the difference between the branching point for the human and the chimpanzee species and that for the gorilla species and the human-chimpanzee group is not statistically significant. In addition to this analysis, various factors that affect the accuracy of an estimated tree are discussed.