A new dynamin-like protein, ADL6, is involved in trafficking from the trans-Golgi network to the central vacuole in Arabidopsis

Dynamin, a high-molecular-weight GTPase, plays a critical role in vesicle formation at the plasma membrane during endocytosis in animal cells. Here we report the identification of a new dynamin homolog in Arabidopsis named Arabidopsis dynamin-like 6 (ADL6). ADL6 is quite similar to dynamin I in its structural organization: a conserved GTPase domain at the N terminus, a pleckstrin homology domain at the center, and a Pro-rich motif at the C terminus. In the cell, a majority of ADL6 is associated with membranes. Immunohistochemistry and in vivo targeting experiments revealed that ADL6 is localized to the Golgi apparatus. Expression of the dominant negative mutant ADL6[K51E] in Arabidopsis protoplasts inhibited trafficking of cargo proteins destined for the lytic vacuole and caused them to accumulate at the trans-Golgi network. In contrast, expression of ADL6[K51E] did not affect trafficking of a cargo protein, H(+)-ATPase:green fluorescent protein, destined for the plasma membrane. These results suggest that ADL6 is involved in vesicle formation for vacuolar trafficking at the trans-Golgi network but not for trafficking to the plasma membrane in plant cells.

A novel dual-specificity protein kinase targeted to the chloroplast in tobacco

The NtDSK1 cDNA encoding a novel chloroplast-targeted protein kinase was identified in Nicotiana tabacum. It contains the kinase domain at the C-terminus and a putative regulatory domain at the N-terminus. The recombinant NtDSK1 underwent autophosphorylation of serine, threonine, and tyrosine residues, indicating that NtDSK1 encodes a functional dual-specificity protein kinase. The NtDSK1-green fluorescent protein fusion protein was targeted to chloroplasts. Furthermore, the NtDSK1 protein was immunodetected in chloroplast fractions isolated from tobacco seedlings. The NtDSK1 mRNA expression was developmentally regulated in different tissues, including anthers and germinating seeds, and strongly stimulated by gibberellin. The mRNA was rapidly light responsive during seedling growth. NtDSK1 may play a role in a light-regulated signaling process in tobacco.

Role of the actin cytoskeleton in T cell absorption and internalization of ligands from APC

A feature of T-APC interaction is that, via either TCR or CD28, T cells can absorb molecules from APC on to the cell surface and then internalize these molecules. Here, using both normal and TCR-transgenic T cells, we investigated the mechanism of T cell absorption of molecules from APC and the role of the cytoskeleton. The results show that although activated T cells could absorb APC molecules in the form of cell fragments, uptake of molecules by resting T cells required direct T-APC interaction. Based on studies with latrunculin B, surface absorption of molecules by resting T cells was crucially dependent upon the actin cytoskeleton for both CD28- and TCR-mediated absorption. Significantly, however, TCR-mediated absorption became strongly resistant to latrunculin B when the concentration of MHC-bound peptide on APC was raised to a high level, implying that the actin cytoskeleton is only important for absorption when the density of receptor/ligand interaction is low. By contrast, in all situations tested, the actin cytoskeleton played a decisive role in controlling T cell internalization of ligands from the cell surface.

Jasmonic acid carboxyl methyltransferase: a key enzyme for jasmonate-regulated plant responses

Methyl jasmonate is a plant volatile that acts as an important cellular regulator mediating diverse developmental processes and defense responses. We have cloned the novel gene JMT encoding an S-adenosyl-l-methionine:jasmonic acid carboxyl methyltransferase (JMT) from Arabidopsis thaliana. Recombinant JMT protein expressed in Escherichia coli catalyzed the formation of methyl jasmonate from jasmonic acid with K(m) value of 38.5 microM. JMT RNA was not detected in young seedlings but was detected in rosettes, cauline leaves, and developing flowers. In addition, expression of the gene was induced both locally and systemically by wounding or methyl jasmonate treatment. This result suggests that JMT can perceive and respond to local and systemic signals generated by external stimuli, and that the signals may include methyl jasmonate itself. Transgenic Arabidopsis overexpressing JMT had a 3-fold elevated level of endogenous methyl jasmonate without altering jasmonic acid content. The transgenic plants exhibited constitutive expression of jasmonate-responsive genes, including VSP and PDF1.2. Furthermore, the transgenic plants showed enhanced level of resistance against the virulent fungus Botrytis cinerea. Thus, our data suggest that the jasmonic acid carboxyl methyltransferase is a key enzyme for jasmonate-regulated plant responses. Activation of JMT expression leads to production of methyl jasmonate that could act as an intracellular regulator, a diffusible intercellular signal transducer, and an airborne signal mediating intra- and interplant communications.

Identification and isolation of differentially expressed genes in osmotically stressed human oral keratinocytes

Complementary DNA fragments which showed differential expression relative to unstressed controls were identified and isolated from human oral keratinocytes exposed to hyperosmotic stress. The up- or downregulation of the expression of nine of these cDNAs in response to osmotic stress was determined by Northern blotting. Sequence analysis showed that clones K-5 and K-46 contained identical sequences. Homology searches revealed that K-13 and K-33 were fragments of unknown genes. Among the upregulated cDNAs, K-16 and K-32 were 94 and 83% identical to chromosome 16 bacterial artificial chromosome (CIT987K-A-418G10) and a cDNA (ai49b01.sl) clone, respectively. Another clone, K-34, encoded a protein 73% identical to Bax epsilon. Among the downregulated genes, K-5/46 and K-45 were 99% identical to the og24d08.s1 cDNA clone and to mitochondrial genes for tRNAs and 12S and 16S ribosomal RNAs, respectively, while K-50 was 100% identical to KIAA0905 protein. The gene expression induced by osmotic stress occurred in parallel with the induction of apoptosis and a reduction in protein biosynthesis. This observation, together with the characteristics of the some of the differentially expressed genes, suggests that among the major events induced in oral keratinocytes by hyperosmotic stress are the induction of apoptosis and a decrease in protein biosynthesis, brought about by upregulation of pro-apoptotic genes and downregulation of genes involved in protein biosynthesis.

The superior and inferior components of Whitnall's ligament

During an orbital dissection in a 60-year-old white male, we came across a very well defined superior and inferior component of Whitnall's ligament (Figure 1). The superior component of Whitnall's ligament is well described and well known to ophthalmologists performing eyelid surgery. The inferior component, however, is not well recognized or described. This cadaver dissection illustrates both Whitnall's components well.

Molecular characterization of the NeIF2Bbeta gene encoding a putative eIF2B beta-subunit in Nicotiana tabacum

The NeIF2Bbeta cDNA encoding beta-subunit of the translation initiation factor 2B (eIF2B-beta) was identified from Nicotiana tabacum through protein interaction with PRK1, a reproductive-organ-specific receptor-like kinase (Park et al., 2000). The eIF2B is a guanine nucleotide-exchange protein that consists of five subunits, which function in the regulation of translation in eukaryotic cells. The NeIF2Bbeta that shows a high homology in the amino acid sequence with other beta-subunits also exhibits sequence similarity to a and delta subunits of eIF2B from yeast and animals. The NeIF2Bbeta gene was expressed in all of the tissues examined, but the mRNA level was higher in reproductive tissues than in vegetative tissues. During anther development, the NeIF2Bbeta mRNA was detected in all stages with a slightly higher level in the earliest stage. The NeIF2Bbeta-GFP fusion protein was mainly localized in the cytosol.

Trafficking of phosphatidylinositol 3-phosphate from the trans-Golgi network to the lumen of the central vacuole in plant cells

Very limited information is available on the role of phosphatidylinositol 3-phosphate (PI[3]P) in vesicle trafficking in plant cells. To investigate the role of PI(3)P during the vesicle trafficking in plant cells, we exploited the PI(3)P-specific binding property of the endosome binding domain (EBD) (amino acids 1257 to 1411) of human early endosome antigen 1, which is involved in endosome fusion. When expressed transiently in Arabidopsis protoplasts, a green fluorescent protein (GFP):EBD fusion protein exhibited PI(3)P-dependent localization to various compartments--such as the trans-Golgi network, the prevacuolar compartment, the tonoplasts, and the vesicles in the vacuolar lumen--that varied with time. The internalized GFP:EBD eventually disappeared from the lumen. Deletion experiments revealed that the PI(3)P-dependent localization required the Rab5 binding motif in addition to the zinc finger motif. Overexpression of GFP:EBD inhibited vacuolar trafficking of sporamin but not trafficking of H(+)-ATPase to the plasma membrane. On the basis of these results, we propose that the trafficking of GFP:EBD reflects that of PI(3)P and that PI(3)P synthesized at the trans-Golgi network is transported to the vacuole through the prevacuolar compartment for degradation in plant cells.

Synergistic antidiabetic activities of zinc, cyclo (his-pro), and arachidonic acid

Previous studies have already shown that prostate extract (PE) has antidiabetic activity when given to animals and humans. In this study, we explore whether this antidiabetic activity is related to the high concentrations of zinc, cyclo (his-pro) (CHP), and the prostaglandin precursor, arachidonic acid (AA), in prostate tissue. When streptozotocin-induced diabetic rats were given drinking water containing 10 mg/L zinc and 100 mg/L PE for 3 weeks, fasting blood glucose levels and glucose clearance rates, but not plasma insulin levels, were significantly lower than at pretreatment. In subsequent experiments, blood glucose levels in rats given PE for 3 weeks were significantly lower than in rats given distilled water or 10 mg/L zinc alone. However, in rats given 100 mg/L CHP with zinc, blood glucose levels were also lower than in rats given PE alone. Time-course studies in diabetic rats given drinking water containing 20 mg/L Zn, 20 mg/L L-histidine, and 10 mg/L CHP showed that blood glucose levels dropped 209 +/- 53 mg/dL in 1 day and stayed low for 2 weeks. When CHP was replaced with 100 mg AA/L, blood glucose levels dropped 230 +/- 64 mg/dL in 5 days, but returned to the original values 11 days later. Growth rate improved and water consumption decreased significantly in CHP- and AA-treated diabetic rats. High intake of L-histidine and testosterone increased blood glucose concentrations in diabetic rats. To determine optimal dosages of CHP and AA, we gave rats drinking water containing 10 mg/L Zn and 0.5 mg/L L-histidine with various concentrations of CHP or AA. The most effective doses for reducing blood glucose levels were 0.32 mg CHP/kg/day and 11 mg AA/kg/day. These data suggest that the active antidiabetic ingredients in the PE are CHP, zinc, and AA or its precursors.

Autoinhibition of a calmodulin-dependent calcium pump involves a structure in the stalk that connects the transmembrane domain to the ATPase catalytic domain

The regulation of Ca(2+)-pumps is important for controlling [Ca(2+)] in the cytosol and organelles of all eukaryotes. Here, we report a genetic strategy to identify residues that function in autoinhibition of a novel calmodulin-activated Ca(2+)-pump with an N-terminal regulatory domain (isoform ACA2 from Arabidopsis). Mutant pumps with constitutive activity were identified by complementation of a yeast (K616) deficient in two Ca(2+)-pumps. Fifteen mutations were found that disrupted a segment of the N-terminal autoinhibitor located between Lys(23) and Arg(54). Three mutations (E167K, D219N, and E341K) were found associated with the stalk that connects the ATPase catalytic domain (head) and with the transmembrane domain. Enzyme assays indicated that the stalk mutations resulted in calmodulin-independent activity, with V(max), K(mATP), and K(mCa(2+)) similar to that of a pump in which the N-terminal autoinhibitor had been deleted. A highly conservative substitution at Asp(219) (D219E) still produced a deregulated pump, indicating that the autoinhibitory structure in the stalk is highly sensitive to perturbation. In plasma membrane H(+)-ATPases from yeast and plants, similarly positioned mutations resulted in hyperactive pumps. Together, these results suggest that a structural feature of the stalk is of general importance in regulating diverse P-type ATPases.

Brazilian hydroxyapatite implant

PURPOSE

To evaluate a synthetic hydroxyapatite (HA) (manufactured in Brazil) in a rabbit model.

METHODS

Nine New Zealand white rabbits underwent enucleation of one eye followed by implantation of either a 12-mm Brazilian synthetic HA implant or a 12-mm BioEye, wrapped in polyglactin 910 mesh. Magnetic resonance imaging was performed to assess fibrovascular ingrowth 4, 8, and 12 weeks after implantation. Three animals were killed at each of the times for histopathologic examination. The Brazilian implant was also examined chemically and by scanning electron microscopy.

RESULTS

The Brazilian HA was found to be heavier than either the BioEye or synthetic FCI3 HA implants. It did not have a visible, regularly arranged interconnected porous architecture. Rather, it had randomly appearing channels apparent on its external and internal surface in addition to large cystic areas within the body of the implant. Scanning electron microscopy revealed the implant to have a microporous architecture in addition to the large channels and cystic cavities. Histopathologically, central vascularization occurred by 4 weeks and was also present at 8 and 12 weeks. In three Brazilian implants an unrecognizable, nonbirefringent material was identified. The cause of it was unclear. Chemical analysis confirmed the implant to consist of pure HA.

CONCLUSION

The Brazilian implant is pure HA that appears solid but has randomly arranged channels as well as a microporous architecture that allows vascularization to its center. It is heavier than other available HA implants and has the presence of an unidentified foreign material within it. Although this implant is less expensive and does not require a costly manufacturing process, the structural characteristics of the material do not offer any theoretical or clinical advantages. The implant is only available in Brazil at this time.

The Molteno M-Sphere

PURPOSE

To analyze a mammalian hydroxyapatite (HA) implant known as the Molteno M-Sphere, recently approved by the Food and Drug Administration of the United States.

METHODS

The authors examined the implant macroscopically, with chemical analysis (x-ray powder diffraction, x-ray fluorescence spectrophotometry), and microscopically with scanning electron microscopy. Animal implantation of six Molteno M-Spheres was carried out in six adult male New Zealand albino rabbits. Implant vascularization was evaluated by means of magnetic resonance imaging and histopathologic sectioning.

RESULTS

The M-Sphere was found to have multiple interconnected pores throughout with an average pore size of 300 microm to 600 microm. This implant was very light-weight (0.31 g) and fragile. It was made up of pure HA. Magnetic resonance imaging studies showed implant enhancement to its center by 4 weeks after implantation. Histopathologically, fibrovascularization occurred uniformly throughout the 4, 8, and 12-week rabbit implants.

CONCLUSIONS

The M-Sphere is an alternative type of HA implant that recently has been reintroduced into the United States for use after enucleation, evisceration, or as a secondary implant. It has multiple interconnected pores allowing central fibrovascularization as early as 4 weeks in a rabbit model. Its light weight and fine trabecular framework, however, are associated with increased implant fragility when compared with other available HA implants (BioEye and FCI3 synthetic HA). The implant requires careful handling because routine handling may damage the implant. The implant is currently approved by the United States Food and Drug Administration.

Phosphorylation-induced signal propagation in the response regulator ntrC

The bacterial enhancer-binding protein NtrC is a well-studied response regulator in a two-component regulatory system. The amino (N)-terminal receiver domain of NtrC modulates the function of its adjacent output domain, which activates transcription by the sigma(54) holoenzyme. When a specific aspartate residue in the receiver domain of NtrC is phosphorylated, the dimeric protein forms an oligomer that is capable of ATP hydrolysis and transcriptional activation. A chemical protein cleavage method was used to investigate signal propagation from the phosphorylated receiver domain of NtrC, which acts positively, to its central output domain. The iron chelate reagent Fe-BABE was conjugated onto unique cysteines introduced into the N-terminal domain of NtrC, and the conjugated proteins were subjected to Fe-dependent cleavage with or without prior phosphorylation. Phosphorylation-dependent cleavage, which requires proximity and an appropriate orientation of the peptide backbone to the tethered Fe-EDTA, was particularly prominent with conjugated NtrC(D86C), in which the unique cysteine lies near the top of alpha-helix 4. Cleavage occurred outside the receiver domain itself and on the partner subunit of the derivatized monomer in an NtrC dimer. The results are commensurate with the hypothesis that alpha-helix 4 of the phosphorylated receiver domain of NtrC interacts with the beginning of the central domain for signal propagation. They imply that the phosphorylation-dependent interdomain and intermolecular interactions between the receiver domain of one subunit and the output domain of its partner subunit in an NtrC dimer precede-and may give rise to-the oligomerization needed for transcriptional activation.

Paenibacillus koreensis sp. nov., a new species that produces an iturin-like antifungal compound

A bacterial strain, YC300T, that produces an iturin-like antifungal antibiotic was isolated from compost and identified as member of the genus Paenibacillus. Gram reaction of the strain was variable depending upon growth stages and culture media. Three different types of colonies were developed on tryptic soy agar. The organism was facultatively anaerobic and grew at 50 degrees C. The DNA G+C content was 54 mol % and anteiso-C15:0 was the major fatty acid. A 0.9 kb fragment was produced by PCR amplification of strain YC300T DNA using primers PAEN515F and 1377R. Levels of 16S rDNA similarity between strain YC300T and other Paenibacillus species were between 89.8 and 94.8%. Phylogenetically, strain YC300T formed a significant monophyletic clade with Paenibacillus validus. It is clear from polyphasic evidence that the isolate should be classified as Paenibacillus koreensis sp. nov., the type strain of which is YC300T (= KCTC 2393T, KCCM 40903T).

A calcium-dependent protein kinase can inhibit a calmodulin-stimulated Ca2+ pump (ACA2) located in the endoplasmic reticulum of Arabidopsis

The magnitude and duration of a cytosolic Ca(2+) release can potentially be altered by changing the rate of Ca(2+) efflux. In plant cells, Ca(2+) efflux from the cytoplasm is mediated by H(+)/Ca(2+)-antiporters and two types of Ca(2+)-ATPases. ACA2 was recently identified as a calmodulin-regulated Ca(2+)-pump located in the endoplasmic reticulum. Here, we show that phosphorylation of its N-terminal regulatory domain by a Ca(2+)-dependent protein kinase (CDPK isoform CPK1), inhibits both basal activity ( approximately 10%) and calmodulin stimulation ( approximately 75%), as shown by Ca(2+)-transport assays with recombinant enzyme expressed in yeast. A CDPK phosphorylation site was mapped to Ser(45) near a calmodulin binding site, using a fusion protein containing the N-terminal domain as an in vitro substrate for a recombinant CPK1. In a full-length enzyme, an Ala substitution for Ser(45) (S45/A) completely blocked the observed CDPK inhibition of both basal and calmodulin-stimulated activities. An Asp substitution (S45/D) mimicked phosphoinhibition, indicating that a negative charge at this position is sufficient to account for phosphoinhibition. Interestingly, prior binding of calmodulin blocked phosphorylation. This suggests that, once ACA2 binds calmodulin, its activation state becomes resistant to phosphoinhibition. These results support the hypothesis that ACA2 activity is regulated as the balance between the initial kinetics of calmodulin stimulation and CDPK inhibition, providing an example in plants for a potential point of crosstalk between two different Ca(2+)-signaling pathways.

Molecular cloning and targeting of a fibrillarin homolog from Arabidopsis

Fibrillarin is a nucleolar protein known to be involved in the processing of ribosomal RNA precursors. We isolated AtFbr1, a cDNA encoding a homolog of fibrillarin in Arabidopsis. The cDNA is 1.2 kb in size and encodes a polypeptide of 310 amino acid residues with a molecular mass of 33 kD. AtFbr1 is expressed at high levels in the flower and root tissue and at a slightly lower level in leaf tissue, whereas it was nearly undetectable in siliques. Expression of AtFbr1 was compared with that of the FLP (fibrillarin-like protein) gene identified by the Arabidopsis genome project. Abscisic acid treatment resulted in the down-regulation of the expression of both AtFbr1 and FLP genes in seedlings, although the degree of suppression was higher for FLP than for AtFbr1. In addition, the expression level of FLP decreased with the age of the seedlings, whereas AtFbr1 did not exhibit any detectable change. The subcellular localization of AtFbrl was studied with an in vivo targeting approach using a fusion protein, and was found to be correctly targeted to the nucleolus in protoplasts when expressed as a green fluorescent fusion protein (GFP). Deletion experiments showed that the N-terminal glycine- and arginine-rich region is necessary and sufficient to target AtFbr1 to the nucleolus.

Preparing currently employed public health nurses for changes in the health system

OBJECTIVES

This article describes a core public health nursing curriculum, part of a larger project designed to identify the skills needed by practicing public health workers if they are to successfully fill roles in the current and emerging public health system.

METHODS

Two focus groups of key informants, representing state and local public health nursing practice, public health nursing education, organizations interested in public health and nursing education, federal agencies, and academia, synthesized material from multiple sources and outlined the key content for a continuing education curriculum appropriate to the current public health nursing workforce.

RESULTS

The skills identified as most needed were those required for analyzing data, practicing epidemiology, measuring health status and organizational change, connecting people to organizations, bringing about change in organizations, building strength in diversity, conducting population-based intervention, building coalitions, strengthening environmental health, developing interdisciplinary teams, developing and advocating policy, evaluating programs, and devising approaches to quality improvement.

CONCLUSIONS

Collaboration between public health nursing practice and education and partnerships with other public health agencies will be essential for public health nurses to achieve the required skills to enhance public health infrastructure.

Calmodulin activation of an endoplasmic reticulum-located calcium pump involves an interaction with the N-terminal autoinhibitory domain

To investigate how calmodulin regulates a unique subfamily of Ca(2+) pumps found in plants, we examined the kinetic properties of isoform ACA2 identified in Arabidopsis. A recombinant ACA2 was expressed in a yeast K616 mutant deficient in two endogenous Ca(2+) pumps. Orthovanadate-sensitive (45)Ca(2+) transport into vesicles isolated from transformants demonstrated that ACA2 is a Ca(2+) pump. Ca(2+) pumping by the full-length protein (ACA2-1) was 4- to 10-fold lower than that of the N-terminal truncated ACA2-2 (Delta2-80), indicating that the N-terminal domain normally acts to inhibit the pump. An inhibitory sequence (IC(50) = 4 microM) was localized to a region within valine-20 to leucine-44, because a peptide corresponding to this sequence lowered the V(max) and increased the K(m) for Ca(2+) of the constitutively active ACA2-2 to values comparable to the full-length pump. The peptide also blocked the activity (IC(50) = 7 microM) of a Ca(2+) pump (AtECA1) belonging to a second family of Ca(2+) pumps. This inhibitory sequence appears to overlap with a calmodulin-binding site in ACA2, previously mapped between aspartate-19 and arginine-36 (J.F. Harper, B. Hong, I. Hwang, H.Q. Guo, R. Stoddard, J.F. Huang, M.G. Palmgren, H. Sze ¿1998 J Biol Chem 273: 1099-1106). These results support a model in which the pump is kept "unactivated" by an intramolecular interaction between an autoinhibitory sequence located between residues 20 and 44 and a site in the Ca(2+) pump core that is highly conserved between different Ca(2+) pump families. Results further support a model in which activation occurs as a result of Ca(2+)-induced binding of calmodulin to a site overlapping or immediately adjacent to the autoinhibitory sequence.

TCR-Mediated internalization of peptide-MHC complexes acquired by T cells

Peptide-major histocompatibility complex protein complexes (pMHCs) on antigen-presenting cells (APCs) are central to T cell activation. Within minutes of peptide-specific T cells interacting with APCs, pMHCs on APCs formed clusters at the site of T cell contact. Thereafter, these clusters were acquired by T cells and internalized through T cell receptor-mediated endocytosis. During this process, T cells became sensitive to peptide-specific lysis by neighboring T cells (fratricide). This form of immunoregulation could explain the "exhaustion" of T cell responses that is induced by high viral loads and may serve to down-regulate immune responses.

Modulating quorum sensing by antiactivation: TraM interacts with TraR to inhibit activation of Ti plasmid conjugal transfer genes

Conjugal transfer of the Ti plasmid pTiC58 is regulated by a quorum-sensing system involving the transcriptional activator TraR and the acyl homoserine lactone autoinducer N-(3-oxo-octanoyl)-L-homoserine lactone (AAI). Activation of tra gene expression by TraR and AAI is inhibited by TraM, an 11 kDa protein also coded for by the Ti plasmid. Previous studies suggested that TraM interferes with TraR activity by directly interacting with the activator protein. Using the yeast two-hybrid system, constructs of Saccharomyces cerevisiae containing a fusion of traR to the B42 domain of the prey plasmid pJG4.5 and a fusion of traM to the lexA gene of the bait plasmid pEG202 produced beta-galactosidase and grew on medium lacking leucine, both phenotypes indicative of an interaction between the two proteins. Early termination mutants and substitution mutants mapping to the C-terminus of TraM were isolated by screening for alleles unable to interfere with TraR activity in Agrobacterium tumefaciens. These mutants all failed to interact with the TraR fusion in the two-hybrid system. An N-terminal deletion mutant of TraM lacking the first 27 residues weakly interacted with TraR in the two-hybrid system whereas deletions of 48 amino acids or more abolished the interaction. As assessed by Western blot analysis, the mutant fusion proteins were produced at levels indistinguishable from that of the wild-type TraM in the yeast tester strain. Mutants of TraR that were not inhibited by TraM in A. tumefaciens were isolated and fell into two classes. In the first, the mutation resulted in increased expression of wild-type TraR. In the second, a proline residue at position 176 was changed to serine (P176 --> S) or to leucine (P176 --> L). The P176 --> S mutant interacted with wild-type TraM, but at a detectably lower level, in the two-hybrid assay. Mutants of TraR with N-terminal deletions as large as 105 amino acids interfered with the ability of TraM to inhibit wild-type TraR in A. tumefaciens. Two-hybrid assays indicated that these mutants, as well as a C-terminal 49 residue fragment of TraR, can interact with TraM. We conclude that TraM and TraR interact in vivo and that this interaction is responsible for inhibition of TraR-mediated activation. We also conclude that the two proteins interact with each other through domains located at their respective C-termini.

Essential components of the Ti plasmid trb system, a type IV macromolecular transporter

The trb operon from pTiC58 is one of three loci that are required for conjugal transfer of this Ti plasmid. The operon, which probably codes for the mating bridge responsible for pair formation and DNA transfer, contains 12 genes, 11 of which are related to genes from other members of the type IV secretion system family. The 12th gene, traI, codes for production of Agrobacterium autoinducer (AAI). Insertion mutations were constructed in each of the 12 genes, contained on a full-length clone of the trb region, using antibiotic resistance cassettes or a newly constructed transposon. This transposon, called mini-Tn5Ptrb, was designed to express genes downstream of the insertion site from a promoter regulated by TraR and AAI. Each mutation could trans complement downstream Tn3HoHo1 insertions in the trb operon of full-sized Ti plasmids. When marker-exchanged into the transfer-constitutive Ti plasmid pTiC58DeltaaccR mutations in trbB, -C, -D, -E, -L, -F, -G, and -H abolished conjugal transfer from strain UIA5, which lacks the 450-kb catabolic plasmid pAtC58. However, these mutants retained residual conjugal transfer activity when tested in strain NT1, which contains this large plasmid. The trbJ mutant failed to transfer at a detectable frequency from either strain, while the trbI mutant transferred at very low but detectable levels from both donors. Only the trbK mutant was unaffected in conjugal transfer from either donor. Transfer of each of the marker-exchange mutants was restored by a clone expressing only the wild-type allele of the corresponding mutant trb gene. An insertion mutation in traI abolished the production of AAI and also conjugal transfer. This defect was restored by culturing the mutant donor in the presence of AAI. We conclude that all of the trb genes except trbI and trbK are essential for conjugal transfer of pTiC58. We also conclude that mutations in any one of the trb genes except traI and trbJ can be complemented by functions coded for by pAtC58.

Hierarchical gene regulatory systems arising from fortuitous gene associations: controlling quorum sensing by the opine regulon in Agrobacterium

Conjugation of the Agrobacterium Ti plasmid pTiC58 is regulated by a hierarchy involving induction by the opines agrocinopines A and B and a quorum-sensing system. Regulation by the opines is mediated by the repressor AccR, while quorum sensing is effected by the transcriptional activator TraR and its ligand, the acyl-homoserine lactone signal molecule Agrobacterium autoinducer (AAI). These last two elements combine to activate expression of the tra system at high population densities. Sequence analysis indicated that traR is the fourth gene of an operon, which we named arc, that is transcribed divergently from accR. Complementation analysis of mutations in the genes 5' to traR showed that the other members of the arc operon are not required for conjugation. Analysis of lacZ reporter fusions demonstrated that traR expression is regulated directly by AccR. Deletion analysis showed that AccR-regulated expression of traR initiates from a promoter located in the intergenic region between accR and orfA, the first gene of the arc operon. Reverse transcriptase-polymerase chain reaction (RT-PCR) and primer extension analyses indicated that the arc transcript initiates upstream of orfA and proceeds uninterrupted through traR. These results are consistent with a model in which quorum sensing is subordinate to the opine regulon because traR has become associated with an operon controlled by the opine-responsive transcriptional regulator.

Physical evidence for a phosphorylation-dependent conformational change in the enhancer-binding protein NtrC

The bacterial enhancer-binding protein nitrogen regulatory protein C (NtrC) activates transcription by sigma54-containing RNA polymerase in a reaction that depends on ATP hydrolysis. Phosphorylation of an aspartate residue in the N-terminal receiver domain of NtrC induces oligomerization of the protein and activates the ATPase activity, which is a function of its central output domain. To study the role of the receiver domain of NtrC, which is known to act positively, we isolated mutant forms of the protein carrying single cysteine residues and derivatized them with a sulfhydryl-specific nitroxide reagent for electron paramagnetic resonance studies. Single cysteines were placed at four positions at which we had obtained constitutive amino acid substitutions, those that yield activity without phosphorylation. In only one case, derivatized C86 in alpha-helix 4 of the receiver domain, did the motion of the side chain become dramatically slower upon phosphorylation. Importantly, derivatized NtrCD86C (NtrCD86C*) activated transcription normally. Additional experiments indicated that the spectral change observed upon phosphorylation of NtrCD86C* was due to interdomain interactions rather than a conformational change within the N-terminal domain itself. These interactions did not appear to occur within a monomer. Although it is not clear whether the spectral change seen upon phosphorylation of NtrCD86C* is due to an interaction that occurs within a dimer of NtrC or requires the formation of higher-order oligomers, the change indicated that alpha-helix 4 of the receiver domain probably plays an important role in communication with the remainder of the protein.

An Arabidopsis GSK3/shaggy-like gene that complements yeast salt stress-sensitive mutants is induced by NaCl and abscisic acid

GSK3/shaggy-like genes encode kinases that are involved in a variety of biological processes. By functional complementation of the yeast calcineurin mutant strain DHT22-1a with a NaCl stress-sensitive phenotype, we isolated the Arabidopsis cDNA AtGSK1, which encodes a GSK3/shaggy-like protein kinase. AtGSK1 rescued the yeast calcineurin mutant cells from the effects of high NaCl. Also, the AtGSK1 gene turned on the transcription of the NaCl stress-inducible PMR2A gene in the calcineurin mutant cells under NaCl stress. To further define the role of AtGSK1 in the yeast cells we introduced a deletion mutation at the MCK1 gene, a yeast homolog of GSK3, and examined the phenotype of the mutant. The mck1 mutant exhibited a NaCl stress-sensitive phenotype that was rescued by AtGSK1. Also, constitutive expression of MCK1 complemented the NaCl-sensitive phenotype of the calcineurin mutants. Therefore, these results suggest that Mck1p is involved in the NaCl stress signaling in yeast and that AtGSK1 may functionally replace Mck1p in the NaCl stress response in the calcineurin mutant. To investigate the biological function of AtGSK1 in Arabidopsis we examined the expression of AtGSK1. Northern-blot analysis revealed that the expression is differentially regulated in various tissues with a high level expression in flower tissues. In addition, the AtGSK1 expression was induced by NaCl and exogenously applied ABA but not by KCl. Taken together, these results suggest that AtGSK1 is involved in the osmotic stress response in Arabidopsis.

The Arabidopsis photomorphogenic mutant hy1 is deficient in phytochrome chromophore biosynthesis as a result of a mutation in a plastid heme oxygenase

The HY1 locus of Arabidopsis is necessary for phytochrome chromophore biosynthesis and is defined by mutants that show a long hypocotyl phenotype when grown in the light. We describe here the molecular cloning of the HY1 gene by using chromosome walking and mutant complementation. The product of the HY1 gene shows significant similarity to animal heme oxygenases and contains a possible transit peptide for transport to plastids. Heme oxygenase activity was detected in the HY1 protein expressed in Escherichia coli. Heme oxygenase catalyzes the oxygenation of heme to biliverdin, an activity that is necessary for phytochrome chromophore biosynthesis. The predicted transit peptide is sufficient to transport the green fluorescent protein into chloroplasts. The accumulation of the HY1 protein in plastids was detected by using immunoblot analysis with an anti-HY1 antiserum. These results indicate that the Arabidopsis HY1 gene encodes a plastid heme oxygenase necessary for phytochrome chromophore biosynthesis.

Characterization of two new channel protein genes in Arabidopsis

Aquaporins, small channel proteins, found in a variety of organisms are members of the major intrinsic protein (MIP) superfamily and have been shown to facilitate water transport when expressed in Xenopus oocytes. We isolated two Arabidopsis cDNAs, SIMIP and SITIP, that encode protein homologues of the MIP superfamily. SIMIP exhibits a high degree of sequence homology to PIP3 and MIP1, and thus may belong to the plasmamembrane intrinsic protein (PIP) subfamily, whereas salt-stress inducible tonoplast intrinsic protein (SITIP) is highly homologous to VM23 and gamma-TIP, and therefore may belong to the TIP subfamily. Expression studies revealed that the two genes showed a different expression pattern. The SIMIP gene was expressed in a tissue-specific manner, for example, its highest transcript level is found in flowers, relatively low levels in siliques, and very low level in leaves and roots. In contrast, SITIP was expressed in nearly equal amounts in all the tissues we examined. Also, the expression of SIMIP and SITIP showed a temporal regulation pattern. For example, the highest expression level was at 1 week after germination. In addition, the transcript levels of SIMIP and SMTIP were increased upon NaCl and ABA treatments. The biological function of the 2 genes were investigated using two NaCl stress-sensitive yeast mutant strains. The mutant yeast cells expressing these 2 genes were more resistant to high NaCl conditions. The results suggest that the proteins encoded by these genes may be involved in the osmoregulation in plants under high osmotic stress such as under a high salt condition.

Molecular cloning of an Arabidopsis cDNA encoding a dynamin-like protein that is localized to plastids

Dynamin-related proteins are high molecular weight GTPase proteins found in a variety of eukaryotic cells from yeast to human. They are involved in diverse biological processes that include endocytosis in animal cells and vacuolar protein sorting in yeast. We isolated a new gene, ADL2, that encodes a dynamin-like protein in Arabidopsis. The ADL2 cDNA is 2.68 kb in size and has an open reading frame for 809 amino acid residues with a calculated molecular mass of 90 kDa. Sequence analysis of ADL2 revealed a high degree of amino acid sequence similarity to other members of the dynamin superfamily. Among those members ADL2 was most closely related to Dnm1p of yeast and thus appears to be a member of the Vps1p subfamily. Expression studies showed that the ADL2 gene is widely expressed in various tissues with highest expression in flower tissues. In vivo targeting experiments showed that ADL2:smGFP fusion protein is localized to chloroplasts in soybean photoautroph cells. In addition experiments with deletion constructs revealed that the N-terminal 35 amino acid residues were sufficient to direct the smGFP into chloroplasts in tobacco protoplasts when expressed as a fusion protein.

Adrenocortical SPECT using iodine-131 NP-59

Adrenal scintigraphy with 131I-labeled 6-beta-iodomethyl-19-norcholesterol (NP-59) is a technically demanding and complex procedure. However, it can provide crucial and unique information about the functional status of the adrenal glands and guide the appropriate therapeutic management of patients with biochemically proven disease. Since the introduction of this new investigational drug, scintigraphic imaging has been performed using conventional planar techniques. We present an interesting case of primary aldosteronism in which planar scintigraphy and SPECT were combined in an attempt to increase the sensitivity of the study. SPECT revealed scintigraphic evidence of bilateral adrenocortical hyperplasia. Interestingly, the CT scan of this patient showed only an equivocal abnormality in the left adrenal gland, suggestive of an adenoma.

Molecular cloning of a novel Ca2+-binding protein that is induced by NaCl stress

Plant responses to high salt stress have been studied for several decades. However, the molecular mechanisms underlying these responses still elude us. In order to understand better the molecular mechanism related to NaCl stress in plants, we initiated the cloning of a large number of NaCl-induced genes in Arabidopsis. Here, we report the cloning of a cDNA encoding a novel Ca2+-binding protein, named AtCP1, which shares sequence similarities with calmodulins. AtCP1 exhibits, in particular, a high degree of amino acid sequence homology to the Ca2+-binding loops of the EF hands of calmodulin. However, unlike calmodulin, AtCP1 appears to have only three Ca2+-binding loops. We examined Ca2+ binding of the protein by a Ca2+-dependent electrophoretic mobility shift assay. A recombinant AtCP1 protein that was expressed in Escherichia coli did show a Ca2+-dependent electrophoretic mobility shift. To gain insight into the expression of the AtCP1 gene, northern blot analysis was carried out. The AtCP1 gene had a tissue-specific expression pattern: high levels of expression in flower and root tissues and nearly undetectable levels in leaves and siliques. Also, the expression of the AtCP1 gene was induced by NaCl treatment but not by ABA treatment. Finally, subcellular localization experiments using an AtCP1:smGFP fusion gene in soybean suspension culture cells and tobacco leaf protoplasts indicate that AtCP1 is most likely a cytosolic protein.

Potent and selective stimulation of memory-phenotype CD8+ T cells in vivo by IL-15

Proliferation of memory-phenotype (CD44hi) CD8+ cells induced by infectious agents can be mimicked by injection of type I interferon (IFN I) and by IFN I-inducing agents such as lipopolysaccharide and Poly I:C; such proliferation does not affect naive T cells and appears to be TCR independent. Since IFN I inhibits proliferation in vitro, IFN I-induced proliferation of CD8+ cells in vivo presumably occurs indirectly through production of secondary cytokines, e.g., interleukin-2 (IL-2) or IL-15. We show here that, unlike IL-2, IL-15 closely mimics the effects of IFN I in causing strong and selective stimulation of memory-phenotype CD44hi CD8+ (but not CD4+) cells in vivo; similar specificity applies to purified T cells in vitro and correlates with much higher expression of IL-2Rbeta on CD8+ cells than on CD4+ cells.

Sequence of a cDNA encoding mouse ribosomal protein S14

An involution-induced clone was identified by differential screening from a cDNA library of mouse mammary gland. The clone was identified as full-length cDNA encoding the 40S subunit of ribosomal protein S14 (rps14). Comparison of the deduced amino acid sequence to sequences of rps14 from humans, hamsters, and rats showed a conservation.

A dynamin-like protein in Arabidopsis thaliana is involved in biogenesis of thylakoid membranes

Dynamin, a GTP-binding protein found in rat brain, plays a role in endocytosis. Suborganellar fractionation studies of Arabidopsis leaf tissue revealed that a dynamin-like protein, ADL1, is localized in the thylakoid membranes of chloroplasts. This notion was supported further by in vivo targeting experiments using an ADL1-green fluorescent fusion protein and immunogold labeling with the anti-ADL1 antibody. Transgenic plants harboring various deletion mutant genes of ADL1 had a yellow leaf phenotype where the cells had very few chloroplasts. In addition, the remaining chloroplasts appeared morphologically not fully developed. The detailed structure of the chloroplasts revealed by electron microscopy showed a greatly reduced amount of thylakoid membranes. Also, the level of thylakoid membrane proteins such as the light-harvesting complex II and CP29 was greatly reduced in these transgenic plants. When we examined the expression of the ADL1 deletion mutant genes, these genes were highly expressed at the transcriptional level. However, the mutant ADL1s were not detectable at the protein level by Western blot analysis. Moreover, the endogenous ADL1 protein level was greatly reduced in these transgenic plants, probably due to a post-transcriptional silencing effect of the transgenes. We propose, therefore, that ADLl is involved in the biogenesis of thylakoid membranes.

Recanalization of chronic peripheral arterial occlusions by alternating intra-arterial rt-PA and PGE1

BACKGROUND

Recanalization of femoral artery occlusions is difficult and different forms of intra-arterial lysis or mechanical procedures have been described. We investigated the effectiveness of a prolonged intra-arterial lysis with rt-pa in combination with PGE1 followed by angioplasty.

PATIENTS AND METHODS

43 patients (age 60.4 +/- 14.3 years) with peripheral arterial occlusions older than 3 months and longer than 10 cm were treated with intra-arterial rt-pa (3 mg in 3 h) followed by PGE1 (2.1 ml/h for 3 h, concentration: 20 micrograms/50 ml NaCl) in alternating order. Treatment times ranged from 1 to 7 days (2.9 +/- 1.6). Doses of 26.5 +/- 21.9 mg rt-PA and 20.4 +/- 16 micrograms PGE1 were used. If necessary, angioplasty was performed after a wire was passed through the lumen.

RESULTS

Recanalization was achieved in 47 out of 85 arterial segments with reocclusion in 9 segments. The arterial perfusion deteriorated once due to peripheral embolism. Other adverse effects included one case of retroperitoneal and one case of intracrural bleeding and one aneurysma spurium.

CONCLUSION

In chronic arterial occlusions which do not respond to conventional angioplasty and/or short term fibrinolysis recanalization may be achieved in about 50% by means of prolonged alternating application of rt-pa and PGE1.

A novel calmodulin-regulated Ca2+-ATPase (ACA2) from Arabidopsis with an N-terminal autoinhibitory domain

To study transporters involved in regulating intracellular Ca2+, we isolated a full-length cDNA encoding a Ca2+-ATPase from a model plant, Arabidopsis, and named it ACA2 (Arabidopsis Ca2+-ATPase, isoform 2). ACA2p is most similar to a "plasma membrane-type" Ca2+-ATPase, but is smaller (110 kDa), contains a unique N-terminal domain, and is missing a long C-terminal calmodulin-binding regulatory domain. In addition, ACA2p is localized to an endomembrane system and not the plasma membrane, as shown by aqueous-two phase fractionation of microsomal membranes. ACA2p was expressed in yeast as both a full-length protein (ACA2-1p) and an N-terminal truncation mutant (ACA2-2p; Delta residues 2-80). Only the truncation mutant restored the growth on Ca2+-depleted medium of a yeast mutant defective in both endogenous Ca2+ pumps, PMR1 and PMC1. Although basal Ca2+-ATPase activity of the full-length protein was low, it was stimulated 5-fold by calmodulin (50% activation around 30 nM). In contrast, the truncated pump was fully active and insensitive to calmodulin. A calmodulin-binding sequence was identified within the first 36 residues of the N-terminal domain, as shown by calmodulin gel overlays on fusion proteins. Thus, ACA2 encodes a novel calmodulin-regulated Ca2+-ATPase distinguished by a unique N-terminal regulatory domain and a non-plasma membrane localization.

The Arabidopsis KNOLLE protein is a cytokinesis-specific syntaxin

In higher plant cytokinesis, plasma membrane and cell wall originate by vesicle fusion in the plane of cell division. The Arabidopsis KNOLLE gene, which is required for cytokinesis, encodes a protein related to vesicle-docking syntaxins. We have raised specific rabbit antiserum against purified recombinant KNOLLE protein to show biochemically and by immunoelectron microscopy that KNOLLE protein is membrane associated. Using immunofluorescence microscopy, KNOLLE protein was found to be specifically expressed during mitosis and, unlike the plasma membrane H+-ATPase, to localize to the plane of division during cytokinesis. Arabidopsis dynamin-like protein ADL1 accumulates at the plane of cell plate formation in knolle mutant cells as in wild-type cells, suggesting that cytokinetic vesicle traffic is not affected. Furthermore, electron microscopic analysis indicates that vesicle fusion is impaired. KNOLLE protein was detected in mitotically dividing cells of various parts of the developing plant, including seedling root, inflorescence meristem, floral meristems and ovules, and the cellularizing endosperm, but not during cytokinesis after the male second meiotic division. Thus, KNOLLE is the first syntaxin-like protein that appears to be involved specifically in cytokinetic vesicle fusion.

EGF inhibits expression of WDNM1 and sulfated glycoprotein-2 genes in mammary epithelial cells

We have previously shown that expressions of ferritin heavy chain (FHC), WDNM1, and sulfated glycoprotein-2 (SGP-2) genes are induced at an involution stage of mammary gland. Here we studied the effect of lactogenic hormones and EGF on the expression of involution-induced genes in HC11 mammary epithelial cells. Insulin, dexamethasone, prolactin, and its combinations did not affect expression of the genes. When cells were cultured in growth medium containing EGF, expression of WDNM1 and SGP-2 genes was strongly inhibited in a dose- and time- dependent manner, whereas expression of FHC gene was not influenced by EGF. Results demonstrate that EGF inhibits expression of WDNM1 and SGP-2 genes in mammary epithelial cells.

A dynamin-like protein, ADL1, is present in membranes as a high-molecular-mass complex in Arabidopsis thaliana

Dynamin, a GTP-binding protein, is involved in endocytosis in animal cells. We found that a dynamin-like protein, ADL1, is present in multiple forms in Arabidopsis leaf tissue. Subcellular fractionation experiments, together with gel-filtration and nondenaturing-gel electrophoresis revealed that most of ADL1 is present as a high-molecular-mass complex of 400 to 600 kD in the membrane or pellet fraction, whereas ADL1 is present in the soluble fraction as a monomer. The subcellular distribution of ADL1 is affected by various agents such as Ca2+, cyclosporin A, GTP, and ATP. Ca2+ increases the amount of ADL1 present in the membrane fraction, whereas cyclosporin A inhibits the membrane association. Furthermore, Ca2+ and GTP change the migration pattern of ADL1 in nondenaturing polyacrylamide gels, indicating that these chemicals influence either the complex formation and/or the conformation of the ADL1 complex. Our results demonstrate that ADL1 has characteristics that are similar to Dynamin I, which is found in animal cells. Therefore, it is possible that ADL1 is also involved in biological processes that require vesicle formation.

Isolation of molecular markers for salt stress responses in Arabidopsis thaliana

Characterization of many osmotic stress-induced genes has greatly contributed to the understanding of the physiological responses of plant cells to osmotic stress at the molecular level. In this study we constructed a subtraction library and generated 15 salt stress-inducible ESTs from this library to use as molecular markers that reflect the cellular responses to salt stress responses in Arabidopsis. The sequence analysis showed that 5 salt stress-inducible ESTs were identical to previously identified genes in Arabidopsis, 6 cDNAs were homologous to known genes found in plants as well as yeast, and 4 cDNAs were new genes. To confirm that expression of these clones are induced by salt stress, we carried out Northern blot analysis. When we examined for 15 cDNA clones, they were indeed induced by NaCl treatment. The induction level was variable among these genes ranging from approximately 2-fold to more than 50-fold. Also, Northern blot analysis revealed that these genes can be divided into three different induction patterns: early induction, late induction, and continuous induction.

A T-DNA gene required for agropine biosynthesis by transformed plants is functionally and evolutionarily related to a Ti plasmid gene required for catabolism of agropine by Agrobacterium strains

The mechanisms that ensure that Ti plasmid T-DNA genes encoding proteins involved in the biosynthesis of opines in crown gall tumors are always matched by Ti plasmid genes conferring the ability to catabolize that set of opines on the inducing Agrobacterium strains are unknown. The pathway for the biosynthesis of the opine agropine is thought to require an enzyme, mannopine cyclase, coded for by the ags gene located in the T(R) region of octopine-type Ti plasmids. Extracts prepared from agropine-type tumors contained an activity that cyclized mannopine to agropine. Tumor cells containing a T region in which ags was mutated lacked this activity and did not contain agropine. Expression of ags from the lac promoter conferred mannopine-lactonizing activity on Escherichia coli. Agrobacterium tumefaciens strains harboring an octopine-type Ti plasmid exhibit a similar activity which is not coded for by ags. Analysis of the DNA sequence of the gene encoding this activity, called agcA, showed it to be about 60% identical to T-DNA ags genes. Relatedness decreased abruptly in the 5' and 3' untranslated regions of the genes. ags is preceded by a promoter that functions only in the plant. Expression analysis showed that agcA also is preceded by its own promoter, which is active in the bacterium. Translation of agcA yielded a protein of about 45 kDa, consistent with the size predicted from the DNA sequence. Antibodies raised against the agcA product cross-reacted with the anabolic enzyme. These results indicate that the agropine system arose by a duplication of a progenitor gene, one copy of which became associated with the T-DNA and the other copy of which remained associated with the bacterium.

Insidious illness in active seniors: decoding atypical presentations

Older athletes and active seniors may have serious medical problems without commonly recognized signs and symptoms. The cases of an older tennis player, a golfer, and a deep-sea sport fisherman illustrate unusual presentations of coronary artery disease, bacterial pneumonia, and peptic ulcer disease in senior patients. Alertness for the effects of coexisting illnesses, chronic use of medicines, reduced physiologic and immunologic reserves, altered pain perception, and symptom denial can facilitate prompt treatment of active senior patients.

Differential expression of two functional serine/threonine protein kinases from soybean that have an unusual acidic domain at the carboxy terminus

Two soybean cDNA clones, SPK-3 and SPK-4, encoding putative protein kinases were isolated and characterized. Both cDNAs encoded approximately 40-kDa serine/threonine kinases with unusual stretches of acidic amino acids in their carboxy-terminal regions, which are highly homologous to PKABA1 from wheat and ASKs from Arabidopsis. These kinases are encoded by one- or two-copy genes in the soybean genome. Notably, SPK-3 and -4 showed different patterns of expression in various soybean tissues. SPK-3 is highly expressed in dividing and elongating tissues of young seedlings but relatively weakly in tissues of mature plants. In contrast, SPK-4 showed relatively high and constitutive expression in all the tissues examined except for leaf tissues of mature plants. Although various stressors, such as dehydration and high salinity, increased the expression of both genes, the induction kinetics were different. The two genes also differed in their response to abscisic acid (ABA). SPK-3 was induced but SPK-4 was not affected by exogenously supplied abscisic acid. In accordance with these expression data analysis of the activity of a chimeric SPK-3 promoter::beta-glucuronidase (GUS) reporter gene by transient expression in tobacco leaves confirmed the inducibility of SPK-3 by salt and ABA. Polyclonal antibodies raised against a recombinant SPK-4 protein produced in Escherichia coli specifically recognized both recombinant SPK-3 and -4 proteins. Kinase assays using affinity-purified SPK-4/ antibody complexes with crude soybean extracts as substrate identified specific phosphorylation of two 41 and 170 kDa soybean proteins that were phosphorylated on serine residues. Taken together, our results suggest that SPK-3, and/or SPK-4 are functional serine protein kinase(s). Furthermore, SPK-3 and -4 may play different roles in the transduction of various environmental stresses.

Imaging quiz: Fever of undetermined origin in a soldier

An athletic 26-year-old black male soldier presented with a 5-week history of intermittent fever up to a maximum of 102 degrees F (38.9 degrees C), 10-lb weight loss, and malaise. He denied any localizing signs or symptoms. At the time of admission his medical, surgical, and travel histories were unremarkable; and the physical exam, including his temperature, was within normal limits. His only medication was occasional use of acetaminophen, and his only lab abnormalities were a blood urea nitrogen of 58 mg/dL and serum creatinine of 3.4 mg/dL.

Purification and characterization of an antifungal PR-5 protein from pumpkin leaves

A 28-kDa antifungal PR-5 protein (PLTP) was purified from pumpkin leaves to homogeneity by using ammonium sulfate fractionation, a regenerated chitin column, and reversed-phase column chromatographies on butyl-Toyopearl and HPLC C18 columns. Analysis of 14 N-terminal amino acid sequences of PLTP shows 100% sequence identity to those of two PR-5 proteins, NP24 from tomatoes and AP24 from tobacco. The identical sequence also exhibited high amino acid sequence homology to that of an osmotin-like protein (OLP; 71%) from tobacco cells and thaumatin (64%), a sweet-tasting protein of Thaumatococcus danielli Bench. When the PLTP was immuno-blotted with antiserum raised against the tobacco OLP, the OLP antibody specifically cross-reacted with the PLTP, suggesting that they share several common epitopes in their tertiary structure of the proteins. The purified PLTP rapidly lyzed hyphal tips of Neurospora crassa at a concentration greater than 200 nM and significantly inhibited the fungal growth of Fusarium oxysporum in an agar-disc plate at a concentration greater than 2 microM. It also shows a synergistic effect with nikkomycin, a chitin synthase inhibitor, for the growth inhibition of Candida albicans.

Detection and Enumeration of a Tagged Pseudomonas fluorescens Strain from Soil by Using Markers Associated with an Engineered Catabolic Pathway

Volume 63, no. 2, p. 602: the article title should read as shown above. [This corrects the article on p. 602 in vol. 63.].

The Bop gene adjacent to the mouse CD8b gene encodes distinct zinc-finger proteins expressed in CTLs and in muscle

The Bop gene (for CD8b opposite) is located immediately upstream of the mouse CD8b gene. Expression of Bop gene transcripts was previously observed in several long term CTL lines and in thymus. The present studies demonstrate that expression of the Bop gene in lymphocytes appears to be confined to CD8-positive cells, and that Bop gene expression is inducible by Con A. They further show that a single Bop gene encodes protein products with distinct amino-terminal sequences that are expressed in CTLs (t-BOP) and in cardiac and skeletal muscle (skm-BOP), as well as what appears to be a noncoding cDNA (t-ncb) expressed only in CTLs. The t-BOP and t-ncb cDNAs in CTLs result from alternative splicing of a single primary transcript, whereas the Bop transcripts expressed in CTLs and in muscle appear to be transcribed from different promoters. The BOP proteins expressed in CTLs and muscle contain zinc finger-like motifs with homology to those of the ETO/MTG8 proto-oncogene and several other proteins of interest. Western blot analysis with a hamster anti-BOP mAb have detected the BOP protein in muscle cells and in COS 7 cells transfected with Bop cDNA constructs.

Distinction between Endoplasmic Reticulum-Type and Plasma Membrane-Type Ca2+ Pumps (Partial Purification of a 120-Kilodalton Ca2+-ATPase from Endomembranes)

Two biochemical types of Ca2+-pumping ATPases were distinguished in membranes that were isolated from carrot (Daucus carota) suspension-cultured cells. One type hydrolyzed GTP nearly as well as ATP, was stimulated by calmodulin, and was resistant to cyclopiazonic acid. This plasma membrane (PM)-type pump was associated with PMs and endomembranes, including vacuolar membranes and the endoplasmic reticulum (ER). Another pump ("ER-type") that was associated mainly with the ER hydrolyzed ATP preferentially, was insensitive to calmodulin, and was inhibited partially by cyclopiazonic acid, a blocker of the animal sarcoplasmic/ER Ca2+ pump. Oxalate stimulation of Ca2+ accumulation by ER-type, but not PM-type, pump(s) indicated a separation of the two types on distinct compartments. An endomembrane 120-kD Ca2+ pump was partially purified by calmodulin-affinity chromatography. The purified polypeptide bound calmodulin reacted with antibodies to a calmodulin-stimulated Ca2+ pump from cauliflower and displayed [32P]phosphoenzyme properties that are characteristic of PM-type Ca2+ pumps. The purified ATPase corresponded to a phosphoenzyme and a 120-kD calmodulin-binding protein on endomembranes. Another PM-type pump was suggested by a 127-kD PM-associated protein that bound calmodulin. Thus, both ER- and PM-type Ca2+ pumps coexist in most plant tissues, and each type can be distinguished from another by a set of traits, even in partially purified membranes.