Prevention and management of reproductive tract infections/sexually transmitted infections.
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The transcription factor WIP2/NO TRANSMITTING TRACT (WIP2/NTT) belongs to the WIP zinc finger family. Loss of WIP/NTT function in Arabidopsis thaliana causes alterations in specific tissues in the gynoecium. It also impairs root development, but only when combined with the loss of WIP4 and WIP5 function, due to redundancy. Certain mutant loss-of-function phenotypes can be recovered by cytokinin application, NTT interacts with cytokinin signaling components, and the phenotypes displayed by plants with increased WIP2/NTT expression also suggest a possible interaction with this pathway. Therefore, the objective of this study was to investigate the relationship between WIP2/NTT and the cytokinin pathway. To overcome the issue of genetic redundancy, we used a commonly used inducible system. We found that WIP2/NTT induction alters cytokinin levels and signaling in a tissue-specific manner, as shown by cytokinin content measurements and TCSn::GFP reporter analysis. Transcriptome analyses revealed candidate target genes related to the cytokinin pathway. Yeast one-hybrid and transactivation assays demonstrated direct NTT binding to regulatory regions of the cytokinin genes ISOPENTENYL TRANSFERASE 5 (IPT5), ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 6 (AHP6), and CYTOKININ OXIDASE/DEHYDROGENASE 7 (CKX7) involved in cytokinin biosynthesis, signaling, and degradation, respectively. Moreover, immunolocalization assays revealed that cytokinin distribution was altered in loss of function mutants and after NTT induction. The results of this work indicate that WIP2/NTT modulates cytokinin homeostasis.
Sexually transmitted diseases comprise one of the most common medical complications of pregnancy. Prompt treatment is essential to minimize the risk of fetal and neonatal adverse consequences. At this time, however, no pharmacologic therapy is routinely employed for the viral STDs during pregnancy, including HIV, HSV, and hepatitis B virus. Appropriate antibiotic treatment, considered in the context of fetal drug effects, provides high cure rates for many of the other sexually transmitted agents. The approach of the emergency physician to STDs centers on recognition and treatment; however, all physicians encountering this patient population have a responsibility to facilitate access to primary prophylaxis for STD. This means ensuring that issues related to education regarding transmission of STDs, safer sex, and sexual contact counseling are addressed initially or via a primary care referral. In the appropriate setting, complications of pregnancy due to STDs should also be addressed.
Two distinct cDNA clones, PcCHI1 and PcCHI2, with high sequence similarity to plant chitinases were isolated from parsley (Petroselinum crispum), expressed in Escherichia coli, and the encoded proteins functionally identified as endochitinases. Different expression patterns of the corresponding mRNAs and proteins in infected and uninfected parsley plants indicated distinct roles of the two isoforms in both pathogen defense and plant development. Infection of parsley leaf buds with Phytophthora sojae resulted in the rapid, transient and highly localized accumulation of PcCHI1 mRNA and protein around infection sites, whereas PcCHI2 mRNA and protein were systemically induced at later infection stages. Similar differences in the timing of induction were observed in elicitor-treated, suspension-cultured parsley cells. In uninfected plants, PcCHI1 mRNA was particularly abundant in the transmitting tract of healthy flowers, suggesting a role in the constitutive protection of susceptible transmitting tissue of the style against pathogen ingress and/or in the fertilization process, possibly by affecting pollen tube growth. Localization of PcCHI2 mRNA and protein in the parenchymatic collenchyme of young pedicels may indicate a function in the constitutive protection of this tissue. In addition to such distinct roles of PcCHI1 and PcCHI2 in preformed and induced pathogen defense, both chitinases may have endogenous regulatory functions in plant development.
Genomic sequencing has identified three different typical plant aspartic proteinases in the genome of Arabidopsis thaliana, named Pasp-A1, A2 and A3. A1 is identical to a cDNA we had previously isolated and the two others produce proteins 81 and 63% identical to that predicted protein. Sequencing of the aspartic proteinase protein purified from Arabidopsis seeds showed that the peptides are derived from two of these genes, A1 and A2. Using gene specific probes, we have analyzed RNA from different tissues and found these three genes are differentially expressed. A1 mRNA is detected in all tissues analyzed and more abundant in leaves during the light phase of growth. The other two genes are expressed either primarily in flowers (A3) or in seeds (A2). Insitu hybridization demonstrated that all three genes are expressed in many cells of the seeds and developing seed pods. The A1 and A3 genes are expressed in the sepals and petals of flowers as well as the outer layer of the style, but are not expressed in the transmitting tract or on the stigmatal surface. The A2 gene is weakly expressed only in the transmitting tissue of the style. All three genes are also expressed in the guard cells of sepals. These data suggest multiple roles for aspartic proteinases besides those proposed in seeds.
A functional analysis of the promoter of the S2-RNase gene from potato was performed in transgenic potato and tobacco plants, using a deletion series of S2-RNase promoter GUS fusions. A detailed histochemical and quantitative analysis of the transgenic tobacco plants revealed that S2 promoter fragments ranging in size from 5.6 kb in length down to 0.2 kb mediate a weak developmentally regulated expression in the pistil, and strong ectopic expression in pollen. In the pistil, different expression patterns were seen depending on the transformant, the predominant one being characterized by expression in the stigma and the transmitting tract of the style, whereas a few plants showed expression exclusively either in the stigma or in the stylar transmitting tissue. All transformants also showed GUS expression in the placental epidermis of the ovary. Two sequences that are conserved between the potato S1-RNase and S2-RNase promoters, termed motif and motif III, are located in a fragment of the S2 promoter extending from position of -200 to bp -100, and motif II, located between by -498 and -480, was identified on the basis of sequence comparisons between pistil-specific promoters. Motif II was found to be dispensible for pistil-specific and for pollen-specific expression. Two submotifs, A and B, were identified with the motif I. Both were essential for expression in the pistil but only B was necessary for expression in pollen. Although motif III has a similar bipartite structure and sequence to motif I, it was not sufficient to confer-either pollen- or pistil-specific expression. However, deletion of motif III abolished pollen-specific expression in transient expression experiments, suggesting that an interaction between the two sequence motifs may be needed to specify cell type-specific expression. In transgenic potato the S2-RNase promoter also mediates expression in pollen and in the pistil; however, significantly fewer plants showed expression than in tobacco, with most plants also exhibiting GUS expression in other issues.
Upon germination on the stigma, pollen tubes elongate in the stylar transmitting tract, aided by female factors, with speed and directionality not mimicked in in vitro pollen tube growth cultures. We have shown that a stylar transmitting tissue arabinogalactan protein (AGP) from Nicotiana tabacum (tobacco), TTS protein, stimulates pollen tube growth in vivo and in vitro and attracts pollen tubes grown in a semi-in vivo culture system. It has been reported that the self-incompatible Nicotiana alata produced a stylar glycoprotein, GaRSGP, which had a backbone polypeptide that shared 97% identity with those of TTS proteins but some of its properties were different from those described for TTS proteins. We report here the characterization of a family of stylar transmitting tissue glycoproteins from N. alata that is virtually identical to tobacco TTS proteins and which we refer to as NaTTS proteins. Like their tobacco counterparts, NaTTS proteins are recognized by the traditional AGP-diagnostic reagent beta-glucosyl Yariv reagent, and they are also recognized by JIM13, a monoclonal antibody against AGP. NaTTS proteins also stimulate pollen tube elongation in vitro and attract pollen tubes in a semi-in vivo pollen tube culture system. Biochemical and immunological characterization of NaTTS proteins revealed that they have extraordinary variability in the extent of sugar modifications of their polypeptide backbones. The extent of sugar modifications on NaTTS proteins significantly affects their biochemical properties, influences how they interact with the transmitting tissue extracellular matrix, and affects their solubility from this matrix. Our results suggest that the strategy used to purify GaRSGP only recovered a less glycosylated, more tightly extracellular matrix-bound sub-population of the entire spectrum of N. alata TTS proteins.
A novel stylar-specific glycosylated protein, sp41, was characterized. Sp41 constitutes greater than 12% of the transmitting tract tissue soluble proteins and is mainly localized in the extracellular matrix. Two cDNA clones corresponding to sp41 mRNA were isolated and sequenced. The decoded sequences are, respectively, 80% and 49% homologous to acidic and basic pathogen-induced (1-3)-beta-glucanases of the leaf. Thus a subfamily of (1-3)-beta-glucanase pathogenesis-related (PR) proteins constitutes one of the major stylar matrix proteins. The accumulation of sp41 transcripts in normally developing and elicitor-treated styles and leaves was followed using an RNase protection assay. During development sp41 transcript accumulation starts well after carpel differentiation. It is first detected in styles at 8 days before anthesis. The maximal level of accumulation is reached during anthesis. Elicitor-treated styles do not accumulate the leaf-type (1-3)-beta-glucanase transcript, although they retain the capacity to synthesize leaf-type pathogenesis-related proteins such as the pathogen-induced acidic chitinase. The developmental regulation of sp41 expression points to a role for them in the normal processes of flowering and reproductive physiology.
cDNA clones encoding a novel proline-rich protein (NaPRP4) have been isolated from a Nicotiana alata stylar cDNA library. The N-terminal part of the derived protein is highly rich in proline (32.2%) and contains several repeats such as Lys-Pro-Pro (7 times) and Pro-Thr-Lys-Pro-Pro-Thr-Tyr-Ser-Pro-Ser-Lys-Pro-Pro (twice); the C-terminal part, on the other hand, has a lower proline content (9.9%) and contains two potential N-glycosylation sites and all the six cysteine residues. Northern blot and in situ hybridisation analyses indicate that expression of the NaPRP4 gene is restricted to cells of the transmitting tract of the style.
Previous work from our lab identified mutants, Mgr3 and Mgr9, of tobacco (Nicotiana tabacum) that produced unusual elongated green outgrowths from placentae in vivo. Similarly appearing stigmatoid growths were described developing from some in vitro cultures of excised placentae of tobacco (Hicks and McHughen, 1974, 1977). Here we report a developmental analysis and comparison of the unusual stigmatoid outgrowths seen in in vitro cultures of wild-type and mutant placentae, as well as the green outgrowths seen in vivo in the mutants. The growths produced by wild-type and mutant placental cultures in vitro, and the growths produced by the mutants in vivo, are identified as abnormal stigmas and styles. Wild-type in vitro placental cultures also produce outgrowths identified as homologs of whole carpels. Carpel fusion is not required for differentiation of stigma, style, transmitting tract, vascular traces, ovary, and ovules in these structures. The type and extent of stigmatoid growth production depends upon the age of the explant at excision and culture initiation. Before ovule primordium initiation, few growths are seen in culture; for a short window of time afterward, the primordia are competent to give rise to stigmatoid and carpelloid growths when cultured. After commitment to ovule development occurs, the primordia produce only ovules when cultured. The behavior of the mutant placental cultures is dimorphic. Explants from early stages behave similarly to wild-type when cultured, but differences between wild-type and the mutant behaviors in culture arise at the time when the stigmatoid growths begin to appear in vivo in the mutants. These results imply that ovule primordia pass through stages of distinct sequential restrictions of fate, first to growth as gynoecia, and then second to growth as ovules. The mutant strains described here perturb the commitment to differentiation as ovules.
Carpels are the ovule-bearing structural units in angiosperms. In Arabidopsis, the specification of carpel identity is achieved by at least two separate pathways: a pathway mediated by the C class gene AG and an AG-independent pathway. Both pathways are negatively regulated by A class genes. Two genes, SPT and CRC, can promote differentiation of carpel tissue independently of AG and are thus components of the AG-independent pathway. CRC and SPT appear to act in a redundant manner to promote the differentiation of subsets of carpel tissues. The carpel primordium is subdivided into regional domains, both medial versus lateral and abaxial versus adaxial. Based on morphological and gene expression analyses, it appears likely that these domains define developmental compartments. The medial domain appears fated to differentiate into the marginal tissue types of the carpel (septum with transmitting tract and placenta with ovules), whereas the lateral domain gives rise to the ovary walls. The expression of ETT defines the abaxial domain, and this gene is involved in the abaxial-adaxial and, possibly, the apical-basal patterning of tissues in the carpel. Once regional domains have been established, the differentiation of tissue and cell types occurs. The MADS-box gene FUL and AGLI/5 are involved in the differentiation of specific tissue types in the valves and valve margins. Thus, the genes identified can be arranged in a functional hierarchy: specification of carpel identity, patterning of the carpel primordium and directing the differentiation of the specialized tissues of the carpel.
Nicotiana alata has a style-specific hydroxyproline-rich glycoprotein (the 120 kDa glycoprotein) which has properties of both extensins and AGPs [19, 20]. The 120 kDa glycoprotein is a soluble component in the extracellular matrix of the transmitting tract of styles where it accounts for ca. 9% of the total buffer-soluble protein. Here we describe the molecular cloning of a cDNA representing the gene NaPRP5 which encodes the backbone of the 120 kDa glycoprotein. Expression of mRNA is restricted to styles, consistent with observations on the distribution of the 120 kDa glycoprotein. Levels of accumulation of the transcript encoding the 120 kDa protein backbone are not altered significantly by pollination with either compatible or incompatible pollen. The protein backbone of the 120 kDa glycoprotein, as predicted by the cDNA sequence, is composed of three distinct domains. The sequence of these domains, together with linkage analysis of the carbohydrate component of the 120 kDa glycoprotein, allows predictions of the likely distribution of substituent glycosyl chains along the protein backbone. The similarity of the C-terminal domains of the 120 kDa glycoprotein and GaRSGP, the galactose-rich style glycoprotein of N. alata, is consistent with the two molecules sharing a common antigenic domain in their backbones [31]. The sharing of domains between distinct hydroxyproline-rich glycoproteins suggests that identification of a glycoprotein of this class solely by its protein or carbohydrate epitope is not valid.
Many angiosperms employ self-incompatibility systems to prevent inbreeding. The simple genetics of such systems have made them attractive models of plant cellular communication. Implicit in the single locus genetics is that only one or a few gene products are necessary for recognition and rejection of incompatible pollen. Results in the sporophytic system of the Brassicaceae suggest that different S-locus products are responsible for the pollen and pistil parts of the recognition and rejection response. In solanaeceous plants, which have a gametophytic self-incompatibility system, the S locus product responsible for the pollen portion of the interaction has not been identified, but ribonucleases encoded by the S-locus (S-RNases) are strongly implicated in the style part of the recognition and rejection reaction. In Nicotiana alata, pollen recognition and rejection occur if its S-allele matches either S-allele in the style. The putative stylar S-RNase is abundant in the transmitting tract, and pollen rejection may be related to action of S-RNase on pollen RNAs. Efforts to understand the molecular basis for pollen recognition and rejection have been limited by the lack of a system for manipulating and expressing S-RNases. Here we use the promoter of a style-expressed gene from tomato to obtain high levels of S-RNase expression in transgenic Nicotiana. Recognition and rejection of N. alata pollen S-alleles occur faithfully in the transgenic plants. Our results show that S-RNases alone are sufficient for pollen rejection in this system.
A basic, hydroxyproline-rich glycoprotein (molecular mass 120 kDa) has been purified from the styles of Nicotiana alata. An antibody, specific for the protein backbone (molecular mass 78 kDa) of the glycoprotein, was used to demonstrate that the glycoprotein is a soluble, style-specific component and that related molecules are present in the styles of other solanaceous species. Linkage analysis of the carbohydrate portion of the glycoprotein, together with antibody binding studies, indicates that the glycoprotein contains both extensin-like and arabinogalactan-protein (AGP)-like side chains. Furthermore, the AGP-like side-chains contain a style-specific epitope that is also present on AGPs from N. alata styles and glycoconjugates from the styles of other members of the Solanaceae. The abundance of this 120 kDa glycoprotein, its location in the extracellular matrix of the transmitting tract and its conservation in several species within the Solanaceae suggests a role in pistil function.
A basic, galactose-rich style glycoprotein (GaRSGP) encoded by a previously characterized style-specific cDNA (NaPRP4) has been isolated from the styles of Nicotiana alata and structurally characterized. The glycoprotein is associated with cell walls in the transmitting tract and is composed of approximately 25% (w/w) protein and 75% (w/w) carbohydrate. The purified glycoprotein appears as a smear of between 45-120 kDa on SDS-PAGE; the deglycosylated protein backbone has an apparent molecular weight of approximately 30 kDa. The glycoprotein is rich in the amino acids lysine, proline, and hydroxyproline and in the monosaccharides galactose and arabinose. It is one of only a few proline/hydroxyproline-rich glycoproteins (P/HRGPs) to be characterized both as a cDNA-clone and protein. Glycans are attached to the protein backbone through both O- and N-glycosidic linkages with the majority of the carbohydrate being O-linked and consisting of short, highly branched chains terminating primarily in galactose residues. A carbohydrate epitope(s) is found on both GaRSGP and another style-specific glycoprotein but not on glycoproteins from other tissues. This finding provides further evidence for the existence of a style-specific carbohydrate epitope(s) which may play a role in style function.
In self-incompatible plants of the Solanaceae, the specificity of pollen rejection is controlled by a single multiallelic S-locus. Pollen tube growth is inhibited in the style when its single S-allele matches either S-allele present in the diploid pistil. Each S-allele encodes an S-RNase with a unique sequence. S-RNases are secreted into the extra-cellular matrix of the transmitting tract which guides pollen tubes toward the ovary. Although it is known that S-RNases are the determinants of S-allele specificity in the pistil, it is not known how allele-specific information is encoded in the sequence. Therefore, we exchanged domains between S-RNases with different recognition specificities and expressed the chimeric proteins in transgenic plants to determine their effects on pollination behavior. Nine chimeric constructs were prepared in which domains from Nicotiana alata SA2- and SC10-RNases were exchanged. Among these nine constructs, the entire S-RNase sequence was sampled by exchanging single variable domains as well as larger blocks of contiguous sequences. The chimeric S-RNases retained enzymatic activity and were expressed at levels comparable to control transformants expressing SA2- and SC10-RNases. However, none of the chimeric S-RNases caused rejection of either SA2- or SC10-pollen. We conclude that the recognition function of S-RNases can be disrupted by alterations in many parts of the sequence. It appears that the recognition function of S-RNase is not localized to a specific domain.
MADS-box genes encode transcription factors that regulate different processes of early and late floral development. A novel type of MADS-box gene, DEFH125, was isolated from a stamen specific cDNA library from Antirrhinum majus. The DEFH125 protein shows extensive similarity over the entire length to AGL17, a root-specific MADS-box protein of Arabidopsis. By sharing amino acid deviations from the consensus MADS-box sequence not found in other MADS-box families, these two proteins constitute a novel MADS-box subfamily. However, in contrast to members of other subfamilies the overall structural similarity between the DEFH125 and AGL17 proteins does not coincide with a similarity of expression patterns and functions. The DEFH125 gene is expressed at detectable levels only in the third whorl when the meiotic division of the pollen mother cell is already accomplished. The DEFH125 protein has been located in the cytoplasm of the vegetative cell within the maturing pollen. Surprisingly, after pollination, the DEFH125 protein is also found in nuclei of cells within the transmitting tract of the carpel. The intriguing role of DEFH125, the first MADS-box transcription factor of this type, in aspects of fertilization, such as pollen maturation, pollen tube formation or pollen tube guidance in the carpel, is discussed.
Flower development and anatomy of Acorus calamus and flower anatomy of A. gramineus were studied. Findings were compared with published reports on paleoherbs. Important developmental features include an abaxially median tepal that is initiated first and is similar to a flower-subtending bract and unidirectional flower development with an inversion of organ initiation sequence in the second tepal whorl. The mature gynoecium is largely synascidiate, but early development of carpels is plicate, and the apocarpous portion persists up to anthesis. The carpels form dorsal bulges on the style, enclosing longitudinal intercarpellary slits. The dominance of the synascidiate portion and the apical position of the placenta result from a late and distinct basal elongation of the gynoecium. Stigma, pollen transmitting tract, and ovary are filled with secretion. Secretory papillae are present from the stigma to the placenta; papillae also occur on the rims of the integuments of the ovules. In the uppermost part of the inflorescence, the adaxial floral sectors are reduced in number and structure, and at the apex of the inflorescence, a peloria-like structure is formed. Developmental and morphological similarities seem to be closer between Acorus and Piperales than between Acorus and other magnoliids.