Convergent evolution of cysteine residues in sperm protamines of one genus of marsupials, the Planigales

A characteristic feature of the sperm P1 protamines of eutherian mammals is the constant presence of six to nine cysteine residues per molecule. During spermiogenesis these residues become oxidized to form a three-dimensional network of disulfide bridges between, and within, protamine molecules in the sperm chromatin. This covalent cross linking strongly stabilizes eutherian sperm nuclei. In contrast, protamines sequenced from teleost fish, birds, monotremes, and marsupials all lack cysteine residues and their sperm nuclei, without the stabilizing cross links, are easily decondensed in vitro. We have now found that one genus of tiny, shrewlike dasyurid marsupials, the Planigales, possess P1 protamines containing five to six cysteine residues. These residues appear to have evolved since the divergence of Planigales from other members of the family Dasyuridae, such as the marsupial mouse, Sminthopsis crassicaudata. We believe this constitutes a case of convergent evolution in a subfamily of dasyurid marsupials toward the cysteine-rich eutherian form of sperm protamine P1.      

Evidence for independent recruitment of zeta-crystallin/quinone reductase (CRYZ) as a crystallin in camelids and hystricomorph rodents

Zeta-crystallin/quinone reductase (CRYZ) is an NADPH oxidoreductase expressed at very high levels in the lenses of two groups of mammals: camelids and some hystricomorph rodents. It is also expressed at very low levels in all other species tested. Comparative analysis of the mechanisms mediating the high expression of this enzyme/crystallin in the lens of the Ilama (Lama guanacoe) and the guinea pig (Cavia porcellus) provided evidence for independent recruitment of this enzyme as a lens crystallin in both species and allowed us to elucidate for the first time the mechanism of lens recruitment of an enzyme- crystallin. The data presented here show that in both species such recruitment most likely occurred through the generation of new lens promoters from nonfunctional intron sequences by the accumulation of point mutations and/or small deletions and insertions. These results further support the idea that recruitment of CRYZ resulted from an adaptive process in which the high expression of CRYZ in the lens provides some selective advantage rather than from a purely neutral evolutionary process.      

Legionella oakridgensis: unusual new species isolated from cooling tower water.

We describe a new species of Legionella represented by 10 strains isolated from industrial cooling towers. Legionella oakridgensis differed genetically from the other seven species of Legionella in DNA hybridization studies and differed serologically in direct fluorescent-antibody tests. The new species, unlike all other species except L. jordanis, did not require added L-cysteine for growth in serial transfer on charcoal-yeast extract agar. L. oakridgensis, as well as three other species tested, required L-cysteine for primary isolation from animal tissues. L. oakridgensis was the only species of Legionella that failed to produce alkaline phosphatase at pH 8.5. In all other respects, it resembled other species of Legionella, including having a high content of branched-chain cellular fatty acids and being pathogenic for guinea pigs. These bacteria have not yet been associated with human disease, but they are potential causes of legionellosis.     

Distribution in brain and retina of four enzymes of acetyl CoA synthesis in relation to choline acetyl transferase and acetylcholine esterase

Eleven regions of mouse brain and twelve layers of monkey retina were assayed for choline acetyl transferase (ChAT), acetylcholine esterase (AChE), and 4 enzymes that synthesize acetyl CoA. The purpose was to seek evidence concerning the source of acetyl CoA for acetylcholine generation. In brain ATP citrate lyase was strongly correlated with ChAT as well as AChE (r=0.914 in both cases). Weak, but statistically significant correlation, was observed between ChAT and both cytoplasmic and mitochondrial thiolase, whereas there was a significant negative correlation between ChAT and acetyl thiokinase. In retina ChAT was essentially limited to the inner plexiform and ganglion cell layers, whereas substantial AChE activity extended as well into inner nuclear, outer plexiform and fiber layers, but no further. ATP citrate lyase activity was also highest in the inner four retinal layers, but was not strongly correlated with either ChAT or AChE (r=0.724 and 0.761, respectively). Correlation between ChAT and acetyl thiokinase was at least as strong (r=0.757), and in the six inner layers of retina, the correlation between ChAT and acetylthiokinase was very strong (r=0.932).Special issue dedicated to Dr. Lawrence Austin     

The effect of electroshock on regional CNS energy reserves in mice

ATP, phosphocreatine, glycogen, glucose and lactate levels were measured in the cerebral cortex, thalamus, cerebellum, brain stem and spinal cord of mice following supramaximal electroshock. During the initial 17 s after the onset of a 2 s electrical stimulus high energy phosphate expenditure exceeded formation in all regions but was slower in spinal cord than in the other regions. In cerebral cortex high energy phosphate utilization continued to exceed formation for 32 s which was twice as long as in any other region studied. Altered levels of metabolites recovered most rapidly in spinal cord and least rapidly in cerebral cortex. Pretreatment with a non-anaesthetic dose of phenobarbitone influenced the effect of electroshock. Most of the clinical seizure was prevented, and increased high energy phosphate utilization was sustained for a much shorter period. Only in cerebral cortex did high energy phosphate expenditure exceed formation for as long as 15 s after the electrical stimulus; but even in this region the excess of expenditure over formation was much less than in untreated animals.     

Isolation and characterization of a human T cell leukemia virus type II from a hemophilia-A patient with pancytopenia.

Human T cell leukemia virus (HTLV) type I has been isolated from the cultured T cells of several patients with adult T cell leukemia (ATL) and has been etiologically linked to ATL. However, HTLV-type II has been isolated only once, from the T cells of a patient with a T cell variant of hairy-cell leukemia. We report here the isolation of HTLV-II-related virus from the cultured T cells of a hemophilia-A patient with pancytopenia. The T cell line (CM) grows in the absence of T cell growth factor. Cord blood T cells were rapidly transformed when co-cultivated with irradiated CM cells. Heterologous competition radioimmunoassays using purified HTLV-I p24 showed the expression of HTLV-IIMO-related protein in these cells. Electron microscopy of the CM cells showed the presence of intracellular and extracellular type C viral particles. Comparison of the proviral genome in the CM cell line and the prototype HTLV-IIMO-containing cell line (MO) by molecular hybridization with probes specific for HTLV-IIMO indicated that restriction cleavage sites were identical. The fresh peripheral blood leukocytes of the patient contained two complete copies of the proviral genome, despite the lack of HTLV-II p24 expression. The virus from the cell line CM is designated as HTLV-IICM to distinguish it from the original HTLV-IIMO isolate.     

Generation of T helper cells in vitro. IV. F1 T helper cells primed with antigen-pulsed parental macrophages are genetically restricted in their antigen-specific helper activity.

A sequential culture technique for the in vitro induction and subsequent assay of T helper cells is employed to examine the histocompatibility requirements for antigen recognition by murine T helper cells. F1 T cells are primed in vitro with antigen-pulsed parental strain macrophages and tested for antigen-specific helper activity in cultures containing anti-Thy 1.2 serum and C treated spleen cells from hapten-primed parental or F1 mice. A semiallogenieic system is used and appropriate controls are included to avoid possible complicating effects of allogeneic interactions. The results indicate that F1 T helper cells preferentially stimulate carrier-specific anti-hapten plaque-forming cell responses in spleen cells which are H-2 identical with the macrophage used initially to prime the T cells. Parental spleen cell cultures do not respond to F1 T helper cells which were primed with the other parental strain macrophage. Supplementing this culture with macrophages which are histocompatible with those used to prime the F1T cells is sufficient to restore T helper cell activity. Thus, the genetic restriction described here is between the primed T cell and the macrophage used to elicit secondary responses and not between the T cell and B cell. The results in this semiallogeneic system, however, do not rule out the possibility of additional allogeneic genetic restrictions in the subsequent interaction of T cells with B cells.