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PubMed1993

Adhesion molecules in skeletogenesis: II. Neural cell adhesion molecules mediate precartilaginous mesenchymal condensations and enhance chondrogenesis.

Neural cell adhesion molecules (NCAM) was expressed transiently by mesenchymal cells in precartilaginous condensations of the embryonic chicken limb but was lost upon differentiation into cartilage. Consequently, NCAM was present in the periphery of the limb anlagen but was absent in the cartilaginous center of the growing limb. To determine NCAM function in limb bud chondrogenesis we incubated dissociated stage 22/23 distal mesenchymal limb bud cells with Fab' fragments of antibodies to NCAM. Cell aggregation was inhibited by incubating the cells with anti-NCAM Fab'. These results suggest that NCAM may mediate the formation of precartilaginous condensations. This hypothesis was further tested using micromass cultures. NCAM expression in micromass cultures in vitro recapitulated that in vivo. NCAM was enriched in condensations of 2 day cultures, but was diminished and concentrically distributed around cartilage nodules in 4 day cultures. Anti-NCAM Fab' fragments reduced the area occupied by precartilaginous condensations and the degree of chondrogenic differentiation. Control antibody against chicken embryo fibroblasts had no effect. The effect of overexpressing NCAM was analyzed by electroporating expression vectors directing the synthesis of chicken NCAM. Limb bud cells cultured after electroporation with an NCAM expression vector displayed larger cartilage nodules and greater chondrogenic differentiation than cells electroporated with vector alone. The expression of NCAM in electroporated cells also increased. Control experiments using plasmids encoding beta-galactosidase indicated that approximately 10% of the limb bud cells were transfected under these conditions. The results suggest that NCAM is involved in the chondrogenesis pathway by mediating the formation of precartilaginous condensations.

Animals↗

PubMed2003

Pseudomonas aeruginosa and Burkholderia cepacia cannot be detected by PCR in the breath condensate of patients with cystic fibrosis.

The collection of sputum for microbiological examination in young cystic fibrosis patients can be very difficult. However, a knowledge of bacterial flora colonizing the patient's airways is of paramount importance for proper antimicrobial therapy. It is also known that cystic fibrosis patients colonized by Pseudomonas species have a poorer prognosis than Pseudomonas-negative patients. Noninvasive ways of diagnosing airway inflammation that require only minimal cooperation of the patient might yield new possibilities for early detection of airway colonisation. The breath condensate method as a noninvasive diagnostic technique seems especially appropriate for use in children. Therefore, the aim of this study was to evaluate whether the breath condensate method could be used for detection of Pseudomonas species in children with cystic fibrosis. In total, 32 breath condensate and seven sputum samples were obtained from 13 cystic fibrosis patients with Pseudomonas aeruginosa- or Burkholderia cepacia-positive sputum culture (20 samples were obtained during forced expiration). PCR for combined detection of Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Burkholderia cepacia was performed. PCR results of all breath condensate samples were negative for Pseudomonas aeruginosa, Stenotrophomonas maltophilia, or Burkholderia cepacia, while all sputum sample results were positive. A minimum DNA quantity of 10 fg could be detected in dilution series of the positive control group. We conclude that the breath condensate method cannot be used as a tool for detection of Pseudomonas species.

Adolescent↗

PubMed2000

Association of focal adhesion kinase with fibronectin and paxillin is required for precartilage condensation of chick mesenchymal cells.

We show that tyrosine phosphorylation of FAK was increased as precartilage condensation occurred, followed by a subsequent decrease in proliferation of in vitro micromass culture of wing bud mesenchymal cells. FAK was associated with fibronectin and paxillin, which were maximal at day 3 of culture. FAK was also associated with signaling molecules such as PLC-gamma and PI3-kinase through c-Src. The beta1 integrin antibody and several inhibitors of signaling molecules such as herbimycin A, U73122, LY294002, as well as cytochalasin D, an actin depolymerizing agent, remarkably decreased tyrosine phosphorylation of FAK and its association with fibronectin and paxillin during condensation. resulting in a marked inhibition of condensation and chondrogenesis. Taken together, our findings suggest that beta1 integrin-mediated interaction of mesenchymal cells and fibronectin signals to accelerate the precartilage condensation through tyrosine phosphorylation of FAK and its association with paxillin. This signaling pathway is required for precartilage condensation and subsequent cartilage nodule formation in chondrogenesis.

Animals↗

PubMed1996

Local delivery of TGF beta2 can substitute for placode epithelium to induce mesenchymal condensation during skin appendage morphogenesis.

Development of skin appendages requires interactions between the epithelium and mesenchyme. Without the epithelium, dermal condensations cannot develop, and those already formed will disintegrate. Here we explored the molecular basis of this epithelial requirement and tried to identify the molecule(s) responsible by using the chick feather bud development as a model. TGF beta2 is a likely candidate because its message is predominantly expressed in the feather bud epithelium, and the protein is enriched in the dermal-epidermal junction within the bud. We tested this hypothesis by placing TGF beta-soaked beads on skin explants. We found that TGF beta2, but not TGF beta1, beads placed on top of epithelially stripped mesenchymes can induce dermal condensations. NCAM and tenascin-C (Tn-C) are expressed and protein kinase C is suppressed in the normal feather bud domain. This molecular organization is lost in denuded mesenchyme but can be restored by TGF beta2-coated beads. Subsequently, the TGF beta2-induced dermal condensations can induce nascent epithelium to form skin appendages. Together with our recent findings that ectopic Sonic hedgehog (Shh) expression causes wider TGF beta expression and larger dermal condensation, these results strongly suggest that TGF beta2 produced by epithelial placode is downstream to Shh and plays a key role in the induction of dermal condensation by activating the expression of NCAM and Tn-C, and by suppressing PKC expression.

Animals↗

PubMed1996

Hyaluronan-mediated aggregation of limb bud mesenchyme and mesenchymal condensation during chondrogenesis.

Cell condensations are the initial structures in the formation of proper cartilage and skeletal patterning in the developing vertebrate limb. Chondrogenic differentiation is dependent upon the cell-cell and/or cell-matrix interactions which take place during the condensation process. Coincident with the onset of condensation is the expression by limb mesenchyme of specific cell surface binding sites for the extracellular matrix macromolecule hyaluronan. The association of hyaluronan with the cell surface can influence the behavior of cells, especially cell aggregation. In this study the possible involvement of hyaluronan as an extracellular linker molecule in the cell-cell adhesion event during mesenchymal condensation was investigated in the avian limb model. Hyaluronan hexasaccharides were used to prevent the multivalent interactions that occur between native hyaluronan macromolecules and the cell surface. Our studies show that hyaluronan is required for early adhesive cell-cell interactions of limb bud mesenchyme and that perturbations of hyaluronan-cell interactions with hyaluronan hexasaccharides result in a delay in the formation of condensations as well as a delay in chondrogenic differentiation of mesenchymal cells in micromass cultures.

Animals↗

PubMed1997

Evaluation of the genotoxic and cytotoxic potential of mainstream whole smoke and smoke condensate from a cigarette containing a novel carbon filter.

A novel carbon filter has been developed which primarily reduces the amount of certain vapor phase constituents of tobacco smoke with greater efficiency than the charcoal filters of cigarettes currently in the market. In vitro indicators of genotoxic and cytotoxic potential were used to compare the cigarette smoke condensate (particulate phase) or whole cigarette smoke (vapor phase and particulate phase) from cigarettes containing the novel carbon filter with smoke condensate or whole smoke from commercial or prototype cigarettes not containing the novel carbon filter. Ames bacterial mutagenicity, sister chromatid exchange (SCE) in Chinese hamster ovary (CHO) cells, and neutral red cytotoxicity assays in CHO cells were utilized to assess the genotoxic and cytotoxic potential of the cigarette smoke condensates. SCE and neutral red cytotoxicity assays were utilized to assess the genotoxic and cytotoxic potential of the whole smoke. As expected, the novel carbon filter did not significantly affect the genotoxic or cytotoxic activity of the smoke condensate, although we did observe that the use of low-nitrogen tobacco reduced the mutagenicity of the condensate in Salmonella typhimurium strain TA98. However, the whole smoke from cigarettes containing the novel carbon filter demonstrated significant reductions in genotoxic and cytotoxic potential compared to cigarettes without the novel carbon filter. The toxicity of the smoke was correlated (r = 0.7662 for cytotoxicity and r = 0.7562 for SCE induction) to the aggregate mass of several vapor phase components (acetone, acetaldehyde, acrolein, acrylonitrile, 1,3-butadiene, ammonia, NOx, HCN, benzene, isoprene, and formaldehyde) in the smoke of the cigarettes utilized in this study. In conclusion, this novel carbon filter, which significantly reduced the amount of carbonyls and other volatiles in mainstream cigarette smoke, resulted in significant reductions in the genotoxic and cytotoxic activity of the smoke as measured by these assays.

Animals↗

PubMed2000

Isotherms of Capillary Condensation Influenced by Formation of Adsorption Films.

Isotherms of capillary condensation are often used to determine the vapor sorption capacity of porous adsorbents as well as the pore size distribution by radii. In this paper, for calculating the volume of capillary condensate and of adsorption films in a porous body, an approach based on the theory of surface forces is used. Adsorption isotherms and disjoining pressure isotherms of wetting films are presented here in an exponential form discussed earlier. The calculations were made for straight cylindrical capillaries of different radii and slit pores of different width. The mechanisms of capillary condensation differ in cylindrical and slit pores. In cylindrical pores capillary condensation occurs due to capillary instability of curved wetting films on a capillary surface, when film thickness grows. In the case of slit pores, coalescence of wetting films formed on opposite slit surfaces proceeds under the action of attractive dispersion forces. Partial volumes of liquid in the state of both capillary condensate and adsorbed films are calculated dependent on the relative vapor pressure in a surrounding media. Copyright 2000 Academic Press.

Journal Article↗

PubMed1995

The structure of the transition state for folding of chymotrypsin inhibitor 2 analysed by protein engineering methods: evidence for a nucleation-condensation mechanism for protein folding.

The 64-residue protein chymotrypsin inhibitor 2 (CI2) is a single module of structure. It folds and unfolds as a single co-operative unit by simple two-state kinetics via a single rate determining transition state. This transition state has been characterized at the level of individual residues by analysis of the rates and equilibria of folding of some 100 mutants strategically distributed at 45 sites throughout the protein. Only one residue, a helical residue (Ala16) buried in the hydrophobic core, has its full native interaction energy in the transition state. The only region of structure which is well developed in the transition state is the alpha-helix (residues 12 to 24). But, the interactions within it are weakened, especially at the C-terminal region. The rest of the protein has varying degrees of weakly formed structure. Thus, secondary and tertiary interactions appear to form concurrently. These data, reinforced by studies on the structures of peptide fragments, fit a "nucleation-condensation" model in which the overall structure condenses around an element of structure, the nucleus, that itself consolidates during the condensation. The high energy transition state is composed of the whole of the molecule making a variety of weak interactions, the nucleus being those residues that make the strongest interactions. The nucleus here is part of the alpha-helix and some distant residues in the sequence with which it makes contacts. The remainder of the protein has to be sufficiently ordered that it provides the necessary interactions to stabilize the nucleus. The nucleus is only weakly formed in the denatured state but develops in the transition state. The onrush of stability as the nucleus consolidates its local and long range interactions is so rapid that it is not yet fully formed in the transition state. The formation of the nucleus is thus coupled with the condensation. These results are consistent with a recent simulation of the folding of a computer model protein on a lattice which is found to proceed by a nucleation-growth mechanism. We suggest that the mechanism of folding of CI2 may be a common theme in protein folding whereby fundamental folding units of larger proteins, which are modelled by the folding of CI2, form by nucleation-condensation events and coalesce, perhaps in a hierarchical manner.

Chymotrypsin↗

PubMed1993

Chromatin condensation behaviour of the Y chromosome in the human testis. I. Evidence for decondensation of distal Yq in germ cells prior to puberty with a switch to Sertoli cells in adults.

The condensation behaviour of the human Y chromosome in germ cells and Sertoli cells of pre- and post-pubertal testes was followed by fluorescence in situ hybridisation using probes for three different regions of the Y chromosome. Patterns of expansion or contraction of signal are taken to reflect degrees of condensation of the related Y chromatin and hence its potential for genetic activity. For probe pHY2.1, which labels the distal non-fluorescent and fluorescent heterochromatin of the Y chromosome (Yq12), an expanded signal seen in gonocytes of the prepubertal testis is superseded by a condensed signal seen in adult germ cells at all but the zygotene stage of meiotic prophase when meiotic pairing takes place. In contrast, Sertoli cells show a condensed signal pre-pubertally but a greatly expanded signal in the adult testis. A totally condensed pHY2.1 signal is found in a chromosomally normal man with Sertoli-cell-only syndrome. It is hypothesised that control over at least some facets of spermatogenesis may not, in the adult, be autonomous to the germ cells, but rather may emanate from the Sertoli cells. Chromatin expansion at zygotene could, however, be important for pairing and crossing over in the XY bivalent, successful synapsis ensuring survival of spermatocytes into the post-meiotic stages.

Adult↗

PubMed1988

Carcinogenicity of Indian bidi and cigarette smoke condensate in Swiss albino mice.

The carcinogenicity of Indian bidi and cigarette smoke condensate given by gavage was studied in Swiss mice. Bidi smoke condensate induced liver haemangiomas in four animals, forestomach papilloma in one animal and carcinomas in two animals, in one of them was in the oesophagus and in the other in the forestomach. At the same dose level cigarette smoke condensate failed to produce any tumour. Similarly, none of the untreated and solvent-treated control mice developed tumour. Chemical analysis of the smoke concensate of bidis and cigarettes showed that condensate from bidis had a higher benzo[a]pyrene level than was observed in cigarette smoke condensate, when compared on the basis of the mass (mg) burnt.

Animals↗

PubMed1981

Golgi orientation and cell behaviour in the developing pattern of chondrogenic condensations in chick limb-bud mesenchyme.

Using a silver-impregnation method, the occurrence and significance of Golgi apparatus orientation has been studied in cells contributing to the cartilage condensations in the developing skeleton of the chick limb bud, both in normal embryos and in the talpid mutant, in which the pattern of condensation in situ, and cell behaviour in vitro, is abnormal. Analysis of photographed sections made up as photomontages with a final magnification of X 1000, indicates a sequence of changing Golgi orientation in the course of establishing cartilage condensations in the mesenchyme in normal limb buds, including at an early stage an orientation of one population of cells towards the condensation centre and of another population in the contrary direction, and a modification of the sequence in the mutant. The changing patterns of cell orientation has been further analysed in scanning electron microscope studies on the formation of cartilage condensations in vitro.

Animals↗

PubMed1988

Analysis of X-ray induced aberrations in mammalian chromosomes by electrofusion induced premature chromosome condensation.

Premature chromosome condensation (PCC) was induced by electrofusion of metaphase cells of an Ehrlich ascites tumor cell line with interphase cells of a Muntjac cell line or of a Chinese Hamster subline. Electrofusion was performed by cell alignment in a weakly inhomogeneous a.c. field of 200 V/cm amplitude (peak-to-peak value) and of 1.7 MHz frequency, followed by the application of a series of breakdown (fusion) pulses of 5 kV/cm strength and 15 microseconds duration. Most of the PCC's were of the G2 type despite the large proportion of G1 and S cells in the suspension. The number of chromatid aberrations observed in electrofused cells which had not been subjected to irradiation was not significantly above the spontaneous level. This indicates that electrofusion, at least as used here, did not lead to lesions expressed as structural aberrations. When interphase cells were irradiated by X-ray doses below 3 Gy before electrofusion PCC analysis showed chromosome damage consisting mainly of breaks and gaps. The frequency of aberrations recorded by PCC was 6 to 40 fold larger than that seen in conventional metaphase analysis. This large increase probably arose because of an effective suppression of the G2 repair of chromosomal lesions by the fast condensation process which took place within about 30 min. This assumption was supported by PCC experiments in which the time between X-irradiation and fusion with subsequent chromosome condensation was varied. The results demonstrated that G2 repair of chromosomal lesions was not detectable until 20 min after fusion with a half-time of the repair kinetics of about 1.5 h. The selectivity of premature chromosome condensation in G2 cells is discussed in terms of the differences between electrofusion and chemically or virally induced fusion. It is assumed that the concentration and the transfer rate of the chromosome condensation factor from the metaphase to the interphase cell are the limiting factors in achieving PCC. This is because the localised permeabilisation of the membrane and the dominance of two-cell fusions are characteristic of electrofusion.

Animals↗

PubMed1988

Condensation of oligoglycines with trimeta- and tetrametaphosphate in aqueous solutions.

The dehydration condensation of glycine with trimetaphosphate in aqueous solution has been reinvestigated. Although it has been reported that the condensation of glycine under the alkaline conditions was brought about through the formation of cyclic acylphosphoramidate and hence the condensation of polyglycines could not occur, we found that the condensation of oligoglycines with trimeta- and tetrametaphosphate in aqueous solution are possible through the formation of their acylphosphates under the neutral or weak acidic conditions. Aqueous solutions of 1.0 M glycylglycine and 1.0 M trimetaphosphate in the various pH from 4.0 to 9.0 were incubated at 38 degrees C. The solutions were analyzed by HPLC with ninhydrin reaction system. Tetraglycine and hexaglycine were detected and their maximum yields were given in the reaction carried out around pH 7. They are approximately 15% and 4% after 30 days, respectively. Analogous experiments were performed with tetrametaphosphate. The results showed a similar pH dependence for the condensation, but the yields were about one-tenth of those of corresponding experiments with trimetaphosphate. Relative rates of dimerization of glycine, diglycine and triglycine in the equimolar concentration were also investigated at pH 6.0 at 38 degrees C. The rates for diglycine and triglycine were approximately twice and four times as large as that for glycine. Relevance of the experiments to chemical evolution is discussed.

Chemical Phenomena↗

PubMed2005

Genome size and chromatin condensation in vertebrates.

Cell membrane-dependent chromatin condensation was studied by flow cytometry in erythrocytes of 36 species from six classes of vertebrates. A positive relationship was found between the degree of condensation and genome size. The distribution of variances among taxonomic levels is similar for both parameters. However, chromatin condensation varied relatively more at the lower taxonomic levels, which suggests that the degree of DNA packaging might serve for fine-tuning the 'skeletal' and/or 'buffering' function of noncoding DNA (although the range of this fine-tuning is smaller than the range of genome size changes). For two closely related amphibian species differing in genome size, change in chromatin condensation under the action of elevated extracellular salinity was investigated. Condensation was steadier and its reaction to changes in solvent composition was more inertial in the species with a larger genome, which is in agreement with the buffering function postulated for redundant DNA. The uppermost genome size in vertebrates (and in living beings in general) was updated using flow cytometry and was found to be about 80 pg (78,400 Mb). The widespread opinion that the largest genome occurs in unicellular organisms is rejected as being based on artifacts.

Animals↗

PubMed1984

Specific modification of the condensation domain of fatty acid synthase and the determination of the primary structure of the modified active site peptides.

Fatty acid synthase from the uropygial gland of goose was inactivated by iodoacetamide with a second-order rate constant of 1.3 M-1 S-1 at pH 6.0 and 25 degrees C. Of the seven component activities of the synthase, only the condensation activity was significantly inhibited by iodoacetamide modification. Since preincubation of the enzyme with acetyl-CoA, but not with malonyl-CoA, protected the enzyme from inactivation by iodoacetamide, it is suggested that iodoacetamide probably modified the primer-binding thiol group at the condensation active site. Determination of the stoichiometry of modification was done using [1-14C]iodoacetamide that was purified by high-performance liquid chromatography. Graphical analysis of the data showed that binding of 1.2 carboxamidomethyl groups per subunit of fatty acid synthase would result in complete inhibition of the enzyme activity, suggesting that there is one condensation domain per subunit of fatty acid synthase. Analysis of the tryptic peptide map of the enzyme that was modified with [1-14C]iodoacetamide in the presence and absence of acetyl-CoA revealed that acetyl-CoA prevented the labeling of a major radioactive peptide and a minor radioactive peptide. These two peptides were purified by high-performance liquid chromatography. Amino acid analysis of these two peptides revealed that the major radioactive peptide contained S-carboxymethylcysteine while the minor radioactive peptide did not. However, the latter peptide contained beta-alanine, suggesting that this peptide was from the acyl carrier protein segment of fatty acid synthase and that the iodoacetamide treatment resulted in modification of the pantetheine thiol, although to a lower extent than the primer-binding thiol. The sequence of the primer-binding active site peptide from the condensation domain was H2N-Gly-Pro-Ser-Leu-Ser-Ile-Asp- Thr-Ala-Cys(carboxamidomethyl)-X-Ser-Ser-Leu-Met-Ala-Leu-Glu-Asn-A la-Tyr-Lys- COOH, the first reported sequence of the condensation active site from a vertebrate fatty acid synthase. The acyl carrier protein segment showed extensive sequence homology with the acyl carrier protein of Escherichia coli, particularly in the vicinity of the phosphopantetheine attachment, and the sequence was H2N-Asp-Val-Ser-Ser-Leu- Asn-Ala-Asp-Ser-Thr-Leu-Ala-Asp-Leu-Gly-Leu-Asp-Ser(4'-phosphopanteth ein e) -Leu-Met-Gly-Val-Glu-Val-Arg-COOH.

Amino Acid Sequence↗

PubMed1991

Role of transforming growth factor-beta in chondrogenic pattern formation in the embryonic limb: stimulation of mesenchymal condensation and fibronectin gene expression by exogenenous TGF-beta and evidence for endogenous TGF-beta-like activity.

The possible role of TGF-beta-like molecules in skeletal pattern formation in the embryonic vertebrate limb was studied by analyzing the mechanism of enhancement of chondrogenesis in chick wing bud mesenchyme in vitro and testing for the presence and distribution of endogenous TGF-beta-like activity in this tissue. Transient exposure (3-6 hr) to TGF-beta 1 (1-2 ng/ml) on the day after plating resulted in a 1.5- to 2-fold enhancement of accumulation of Alcian blue (pH 1.0)-stainable extracellular matrix 5 days later. The enhancement of differentiation was preceded by an acceleration and an increase in the extent of precartilage condensation formation, visualized by Hoffman Modulation Contrast microscopy a day after TGF-beta treatment. In contrast, neither condensation nor subsequent chondrogenesis was stimulated by transient treatment with TGF-beta 1 on the day of plating. The effectiveness of a TGF-beta treatment regimen in enhancing chondrogenesis was correlated with its effectiveness in stimulating condensation formation. Exposures to the factor for 3-6 hr on the day after plating, which most consistently stimulated both condensation formation and chondrogenesis, also corresponded to a peak in the enhancement of the steady-state level of fibronectin mRNA (fourfold to eightfold over control levels) measured at the end of the treatment period. The elevation in fibronectin mRNA levels brought about by this treatment persisted throughout the period of condensation. Endogenous TGF-beta-like activity was detected in limb mesenchyme: extracts of freshly isolated and cultured limb tissues contained 6-25 pg TGF-beta-like activity per 1 x 10(6) cells by the Mv1Lu cell proliferation inhibition assay, and indirect immunofluorescence using a polyclonal antibody directed against a TGF-beta-related peptide indicated a patchy distribution of endogenous TGF-beta-like reactivity within a day after culture. These findings are discussed in relation to the "fibronectin prepattern" hypothesis for limb pattern formation.

Animals↗

PubMed1983

Relationship between histone phosphorylation and premature chromosome condensation.

The relationship between histone phosphorylation and chromosome condensation was investigated by determining changes in phosphorylation levels of histones H1 and H3 following fusion between mitotic and interphase cells and subsequent premature chromosome condensation. We detected significant increases in the levels of phosphorylation of H1 and H3 from interphase chromatin in which a majority of nuclei had undergone premature chromosome condensation. In addition, we noted significant decreases in the phosphate content of the highly phosphorylated mitotic H1 and H3, presumably resulting from phosphatase activity contributed by the interphase component of mitotic/interphase fused cells. These observations further strengthen the correlation between histone phosphorylation and the changes in chromosome condensation associated with the initiation of mitosis. This study also suggests that maintenance of the mitotic chromosomes in a highly condensed state does not require the continued presence of histones in a highly phosphorylated form.

Cell Nucleus↗

PubMed1984

Dycal: physical properties and resistance to amalgam condensation.

Simulated clinical experiments showed that the hand condensation of amalgam on single or multiple layers of Dycal in Class II cavities does not cause significant fracture or displacement of the liner. Cyclic loading experiments demonstrated that the plastic deformation of Dycal decreases and its stiffness increases with each additional load cycle. This indicates that minor displacement of Dycal during amalgam condensation occurs mainly during the first thrusts with the condenser, and that its mechanical properties are improved by repeated condensation with heavy pressure. Cyclic loading tests may be of considerable value in the evaluation of the performance of liners during amalgam condensation.

Calcium Hydroxide↗