Transcription of the Hsp30, Hsp70, and Hsp90 heat shock protein genes is modulated by the PalA protein in response to acid pH-sensing in the fungus <Emphasis Type="Italic">Aspergillus nidulans</Emphasis>

Heat shock proteins are molecular chaperones linked to a myriad of physiological functions in both prokaryotes and eukaryotes. In this study, we show that the Aspergillus nidulans hsp30 (ANID_03555.1), hsp70 (ANID_05129.1), and hsp90 (ANID_08269.1) genes are preferentially expressed in an acidic milieu, whose expression is dependent on the palA ⁺ background under optimal temperature for fungal growth. Heat shock induction of these three hsp genes showed different patterns in response to extracellular pH changes in the palA⁺ background. However, their accumulation upon heating for 2 h was almost unaffected by ambient pH changes in the palA ⁻ background. The PalA protein is a member of a conserved signaling cascade that is involved in the pH-mediated regulation of gene expression. Moreover, we identified several genes whose expression at pH 5.0 is also dependent on the palA ⁺ background. These results reveal novel aspects of the heat- and pH-sensing networks of A. nidulans.     

In situ detection of cytomegalovirus DNA in biopsies of AIDS patients using a hybrido-immunocytochemical assay

An in situ hybrido-immunocytochemical assay, with a digoxigenin-labelled probe, was used to show the presence of cytomegalovirus DNA in both paraffin and frozen sections from tissue blocks of 5 AIDS patients. The hybridization probe was constructed by using two different DNA fragments of the repeated sequences of the CMV genome. The CMV DNA probe hybridized in situ was immunocytochemically visualized by anti-digoxigenin Fab fragments labelled with alkaline phosphatase. This hybridization procedure proved to be sensitive, specific, and provided good resolving power. Thus, it might effectively be employed in immunohistological and virological laboratories for the diagnosis of CMV infections in AIDS patients; indeed it might even be applied further in the virological context.     

Double immunoenzymatic staining for the simultaneous detection of Epstein-Barr virus induced antigens

A double indirect immunoenzymatic staining was developed for the simultaneous visualization of Epstein-Barr virus-induced early antigens and virus capsid antigens in P3HR1 lymphoblastoid cell line. The double immunocytochemical staining was performed with a four-stage and a two-stage procedure employing human sera and monoclonal antibodies against Epstein-Barr virus-induced antigens, followed by the addition of specific alkaline phosphatase and peroxidase labeled antisera. The selection of substrates yielding reaction products of contrasting colours enabled the observer to distinguish cells expressing Epstein-Barr virus capsid antigens (blue) from cells expressing Epstein-Barr virus early antigens (brown).     

Serological response to chlamydial infection in sheep, studied by enzyme-linked immunosorbent assay and immunoblotting

Abstract Two enzyme-linked immunosorbent assays (ELISA) using highly purified elementary bodies (EB) of Chlamydia psittaci A/22 strain (ovine) or 6BC strain (psittacine) were set up for the detection of antichlamydial antibodies in sheep. No significant differences were observed between the two ELISAs, whereas these tests proved to be more sensitive than complement fixation test and showed a good correlation ( r = 0.75) with immunofluorescence assay. The periodate treatment of chlamydial antigens modified the results of serological responses studied by ELISA, depending on the sera. The average reduction of ELISA values by periodate was 28%, ranging between 5% and 65%. The immunoblot analysis of sheep sera showed high cross reactivity between the polypeptides of A/22 and 6BC strains. However, some differences were observed. The major outer membrane protein (MOMP) of 6BC strain was recognized at different molecular weight position (40 000 kDa) in comparison with the MOMP of A/22 strain (38 000 kDa). In addition, a clear band of 97 000 kDa was detected by all sheep sera tested with A/22 strain. This band was undetectable in the blots performed with 6BC strain.     

Partial characterization of an 89-kDa highly immunoreactive protein from Chlamydia psittaci A/22 causing ovine abortion

An 89-kDa immunogen from Chlamydia psittaci A/22 causing ovine abortion was partially characterized. The 89-kDa protein, localized on the outer membrane complex of chlamydiae, was synthesized relatively early in the developmental cycle. The protein contained cysteine but was not extensively cross-linked by disulfide bonds. Treatment with proteases apparently did not cleave the protein. The infectivity of strain A/22 was partially (60%) reduced by treatment of chlamydial elementary bodies with monoclonal antibody BS/89 specifically reacting with the 89-kDa antigen. Species-specific as well as strain-specific antigenic determinants were present on the 89-kDa protein.     

Ribonucleic Acid Polymerase Induced by Vaccinia Virus: Lack of Inhibition by Rifampicin and α-Amanitin

The RNA polymerase activity present in the cytoplasm of BHK cells infected with vaccinia virus is not affected by rifampicin or by alpha-amanitin.