A generalised transducing bacteriophage for Rhodococcus erythropolis

Summary Q4, a bacteriophage isolated from soil, mediated the transduction of a number of unlinked markers in Rhodococcus erythropolis. Highest numbers of transductants were obtained at multiplicities of infection of over 100, transductants only being obtained because of the temperate nature of the phage. Under optimal conditions, transduction to prototrophy of auxotrophic markers was over 50 times the spontaneous reversion rate and transduction of some antibitic resistance markers was over 10 times the spontaneous mutation rate. Segregation of unselected, but linked, markers was observed and the phage was used to order loci in a three factor cross. The virus required magnesium ions. Highest phage titres and greatest transduction frequency were obtained with stationary phase cultures.     

Fine needle aspiration cytology of neuroblastoma, including peripheral neuroectodermal tumor, with immunocytochemical and ultrastructural confirmation

Eleven fine needle aspiration (FNA) biopsies were performed on seven children with neuroblastoma, including one patient with a congenital neuroblastoma and another with a peripheral neuroblastoma of the thoracopulmonary region. FNA cytology made the primary diagnosis of neuroblastoma in four of the seven cases. The other biopsies documented local recurrences and metastases to liver, lymph nodes, orbit and breast. The cytologic features included varying numbers of small primitive cells with scanty cytoplasm, poorly to well-formed pseudorosettes, cell processes, a fibrillary matrix and multinucleated ganglion cells. Five of the seven patients had electron microscopic (EM) examination of the FNA specimen, which in all cases confirmed the diagnosis. Batteries of immunoperoxidase stains were performed on all 11 aspirates with variable results. Staining for neuron-specific enolase was positive in four of the five neoplasms tested, although strongly positive in only three of the cases. Staining for neurofilament markers was positive in only two of five tumors. Studies for cytokeratin markers (AE1/3), low-molecular-weight cytokeratin (35BH11), hematopoietic markers (T29/33), immunoglobulin light chains and myoglobin were negative. One case was positive for vimentin. This study attests to the value of FNA cytology in suggesting a correct diagnosis of either primary, recurrent or metastatic neuroblastoma in children. Selective use of immunoperoxidase stains and EM on the aspirates may be of value.     

Immunological studies of Escherichia coli mutants lacking one or two ribosomal proteins

Summary A battery of immunological tests were used to investigate mutants which had been determined as lacking one or two ribosomal proteins on the basis of two-dimensional polyacrylamide gels. Proteins which were confirmed as missing from the ribosome in one or more mutants were large subunit proteins L1, L15, L19, L24, L27, L28, L30 and L33 and small subunit proteins S1, S9, S17 and S20. Cross-reacting material (CRM) was also absent from the post-ribosomal supernatant except in the case of protein S1. Since mutants lacking protein L11 have been previously described, any one of 13 of the 52 ribosomal proteins can be missing. None of these 13 proteins, except S1, can therefore have an indispensable role in ribosome function or assembly. In several mutants in which a protein was not missing but altered, it was present as several moieties of differing charge and size.     

Cytology of pyelitis glandularis cystica. A case report.

Cytologic findings that occur in association with proliferative lesions involving von Brunn's nests in the urinary tract are rare. Such lesions are probably far more common than recognized and are probably considered in the clinicoradiologic differential diagnosis when space-occupying lesions are found, particularly in the upper urinary tract. Reported here are the cytologic findings in a case of pyelitis glandularis cystica that presented as a renal pelvic lesion.     

The distance between S1, S21, and the 3' end of 16S RNA in 30S ribosomal subunits. The effect of poly(uridylic acid) and 50S subunits on these distances

The apparent distances between probes covalently attached to the cysteine thiols of S1 or S21 and the 3' end of 16S RNA in Escherichia coli 30S ribosomal subunits were determined by non-radiative energy transfer to be: S21-16S RNA, 5.1 nm; S21-S1, 6.9 nm; S1-16S RNA, 6.8 nm. Binding of poly(uridylic acid) to 30S subunits causes the apparent distances between S1 and 16S RNA or S21 and 16S RNA to increase by more than 1.2 nm and 0.5 nm, respectively, but has little or no effect on the S1-S21 distance. Binding of 50S subunits causes an apparent increase in the S21-16S RNA and S21-S1 distances by 1.0 nm and 0.8 nm, respectively, but has little or no effect on the S1-16S-RNA distance.     

Mutational alterations in 50 proteins of the Escherichia coli ribosome.

Summary A strain of Escherichia coli, VT, which spontaneously gives rise to mutations in many ribosomal proteins, has been used in conjunction with chemical mutagenesis and varying the subsequent incubation temperature to select mutants which have alterations in every ribosomal protein amenable to analysis of 70 S proteins on two-dimensional polyacrylamide gels under standard conditions. Alterations have been detected in 50 ribosomal proteins, namely in 20 from the small and in 30 from the large subunit. This is the most complete set of mutants with altered ribosomal proteins described so far. The difficulty until recently in obtaining mutations in most ribosomal proteins arises not because they are lethal, as has often been supposed, but because of the lack of a suitable selection heretofore.Communicated by E. Bautz     

A point mutation in ribosomal protein L7/L12 reduces its ability to form a compact dimer structure and to assemble into the GTPase center

An Escherichia coli mutant, LL103, harboring a mutation (Ser15 to Phe) in ribosomal protein L7/L12 was isolated among revertants of a streptomycin-dependent strain. In the crystal structure of the L7/L12 dimer, residue 15 within the N-terminal domain contacts the C-terminal domain of the partner monomer. We tested effects of the mutation on molecular assembly by biochemical approaches. Gel electrophoretic analysis showed that the Phe15-L7/L12 variant had reduced ability in binding to L10, an effect enhanced in the presence of 0.05% of nonionic detergent. Mobility of Phe15-L7/L12 on gel containing the detergent was very low compared to the wild-type proteins, presumably because of an extended structural state of the mutant L7/L12. Ribosomes isolated from LL103 cells contained a reduced amount of L7/L12 and showed low levels (15-30% of wild-type ribosomes) of activities dependent on elongation factors and in translation of natural mRNA. The ribosomal activity was completely recovered by addition of an excess amount of Phe15-L7/L12 to the ribosomes, suggesting that the mutant L7/L12 exerts normal functions when bound on the ribosome. The interaction of Ser15 with the C-terminal domain of the partner molecule seems to contribute to formation of the compact dimer structure and its efficient assembly into the ribosomal GTPase center. We propose a model relating compact and elongated forms of L7/L12 dimers. Phe15-L7/L12 provides a new tool for studying the functional structure of the homodimer.     

Spatio‐temporal scaling of biodiversity and the species–time relationship in a stream fish assemblage

1. The increase of species richness with the area of the habitat sampled, that is the species–area relationship, and its temporal analogue, the species–time relationship (STR), are among the few general laws in ecology with strong conservation implications. However, these two scale‐dependent phenomena have rarely been considered together in biodiversity assessment, especially in freshwater systems. 2. We examined how the spatial scale of sampling influences STRs for a Central‐European stream fish assemblage (second‐order Bernecei stream, Hungary) using field survey data in two simulation‐based experiments. 3. In experiment one, we examined how increasing the number of channel units, such as riffles and pools (13 altogether), and the number of field surveys involved in the analyses (12 sampling occasions during 3 years), influence species richness. Complete nested curves were constructed to quantify how many species one observes in the community on average for a given number of sampling occasions at a given spatial scale. 4. In experiment two, we examined STRs for the Bernecei fish assemblage from a landscape perspective. Here, we evaluated a 10‐year reach level data set (2000–09) for the Bernecei stream and its recipient watercourse (third‐order Kemence stream) to complement results on experiment one and to explore the mechanisms behind the observed patterns in more detail. 5. Experiment one indicated the strong influence of the spatial scale of sampling on the accumulation of species richness, although time clearly had an additional effect. The simulation methodology advocated here helped to estimate the number of species in a diverse combination of spatial and temporal scale and, therefore, to determine how different scale combinations influence sampling sufficiency. 6. Experiment two revealed differences in STRs between the upstream (Bernecei) and downstream (Kemence) sites, with steeper curves for the downstream site. Equations of STR curves were within the range observed in other studies, predominantly from terrestrial systems. Assemblage composition data suggested that extinction–colonisation dynamics of rare, non‐resident (i.e. satellite) species influenced patterns in STRs. 7. Our results highlight that the determination of species richness can benefit from the joint consideration of spatial and temporal scales in biodiversity inventory surveys. Additionally, we reveal how our randomisation‐based methodology may help to quantify the scale dependency of diversity components (α, β, γ) in both space and time, which have critical importance in the applied context.