scholarly journals Mannose 6-phosphate receptor-mediated endocytosis of acid hydrolases: internalization of beta-glucuronidase is accompanied by a limited dephosphorylation.

1986 ◽  
Vol 103 (5) ◽  
pp. 1817-1827 ◽  
Author(s):  
C A Gabel ◽  
S A Foster
Keyword(s):  
Sialic Acid ◽  
Single Species ◽  
Sialic Acid Residue ◽  
Acid Hydrolases ◽  
Chase Period ◽  
L Cells ◽  
High Mannose ◽  
Mannose 6 Phosphate ◽  
The One ◽  
Input Form

Endocytosis of acid hydrolases via the cell surface mannose 6-phosphate (Man 6-P) receptor results in the delivery of the enzymes to lysosomes. To examine the fate of the ligand-associated phosphorylated high mannose oligosaccharides, we have analyzed the asparagine-linked oligosaccharides attached to beta-glucuronidase after uptake and processing by Man 6-P receptor-positive mouse L cells. beta-Glucuronidase, double-labeled with [2-3H]mannose and [35S]methionine, was isolated from the growth medium of mouse P388D1 cells. 80% of the [3H]mannose associated with the secreted enzyme was recovered as high mannose-type oligosaccharides, and 24-37% of these units were phosphorylated. Three species of phosphorylated oligosaccharides were identified; high mannose-type units containing either one or two phosphomonoesters, and hybrid-type units containing one phosphomonoester and one sialic acid residue. After endocytosis by the L cells, the beta-glucuronidase molecules migrated faster on an SDS gel, suggesting that the enzymes had been processed within lysosomes. Examination of the cell-associated beta-glucuronidase molecules indicated that: (a) the percentage of phosphorylated oligosaccharides remained comparable to the input form of the enzyme, even after a 24-h chase period, (b) the presence of a single species of phosphorylated oligosaccharide that contained one phosphomonoester, and (c) the positioning of the phosphate within the intracellular monophosphorylated species was comparable to the positioning of the phosphate within the two phosphomonoester species originally secreted by the P388D1 cells. Therefore, the internalized beta-glucuronidase molecules undergo a limited dephosphorylation; oligosaccharides containing two phosphomonoesters are converted to monophosphorylated species, but the one phosphomonoester forms are conserved. A comparison of the phosphorylated oligosaccharides recovered from ligands internalized by the L cells at 37 degrees and 20 degrees C indicated that: (a) molecules internalized at 20 degrees C retain a higher percentage of phosphorylated structures; and (b) at both temperatures the predominant phosphorylated oligosaccharide contains a single phosphomonoester group. The results indicate that the Man 6-P recognition marker persists after endocytosis and delivery to lysosomes and support the possibility that the limited dephosphorylation of the oligosaccharides may occur en route to these organelles.

scholarly journals Lysosomal enzyme trafficking in mannose 6-phosphate receptor-positive mouse L-cells: demonstration of a steady state accumulation of phosphorylated acid hydrolases.

1986 ◽  
Vol 102 (3) ◽  
pp. 943-950 ◽  
Author(s):  
C A Gabel ◽  
S A Foster
Keyword(s):  
Steady State ◽  
Gradient Centrifugation ◽  
Human Fibroblasts ◽  
Absolute Number ◽  
Acid Hydrolases ◽  
Chase Period ◽  
L Cells ◽  
High Mannose ◽  
Mannose 6 Phosphate ◽  
Enzyme Deficient

During their transport from the endoplasmic reticulum to lysosomes, newly synthesized acid hydrolases are phosphorylated in the Golgi apparatus to generate a common recognition marker, mannose 6-phosphate (Man 6-P). The phosphorylated acid hydrolases then bind to the Man 6-P receptor and are transported by an unknown route to lysosomes. To learn more about the delivery pathway, we examined the fate of the phosphorylated oligosaccharides synthesized by a Man 6-P receptor-positive line of mouse L-cells. In contrast to the rapid degradation of the recognition marker previously observed in mouse lymphoma cells (Gabel, C. A., D. E. Goldberg, and S. Kornfield. 1982. J. Cell Biol., 95:536-542), the number of high mannose oligosaccharides phosphorylated by the L-cells after a 30-min pulse labeling with [2-3H]mannose increased continuously during a subsequent 4-h chase period to a maximum of 9.3% of the total cell-associated structures. After 19 h of chase the absolute number of phosphorylated oligosaccharides declined, but the loss was accompanied by a general loss of cellular oligosaccharides such that 7.4% of the cell-associated high mannose oligosaccharides remained phosphorylated. The longevity of the Man 6-P recognition marker in the L-cells was verified by analyzing the ability of an individual acid hydrolase, beta-glucuronidase, to serve as a ligand for the Man 6-P receptor. At least 60% of the steady state beta-glucuronidase molecules isolated from the L-cells could undergo receptor-mediated endocytosis into enzyme-deficient human fibroblasts. Dense lysosomal granules isolated by metrizamide gradient centrifugation from [3H]mannose-labeled L-cells were found to be highly enriched in their content of phosphomonoester-containing oligosaccharides. The data indicate that acid hydrolases may retain their Man 6-P recognition markers within lysosomes, and suggest the possibility that dephosphorylation occurs at a nonlysosomal location through which the newly synthesized enzymes pass en route to lysosomes.

scholarly journals Postendocytic maturation of acid hydrolases: evidence of prelysosomal processing.

1987 ◽  
Vol 105 (4) ◽  
pp. 1561-1570 ◽  
Author(s):  
C A Gabel ◽  
S A Foster
Keyword(s):  
Cell Surface ◽  
Extracellular Enzymes ◽  
Gradient Centrifugation ◽  
Acid Hydrolase ◽  
Acid Hydrolases ◽  
Lysosomal Compartment ◽  
L Cells ◽  
A Site ◽  
Endocytic Vesicles ◽  
Input Form

The mannose 6-phosphate (Man 6-P) receptor operates to transport both endogenous newly synthesized acid hydrolases and extracellular enzymes to the lysosomal compartment. In a previous study (Gabel, C. A., and S. A. Foster, 1986, J. Cell Biol., 103:1817-1827), we noted that beta-glucuronidase molecules internalized by mouse L-cells via the Man 6-P receptor undergo a proteolytic cleavage and a limited dephosphorylation. In this report, we present evidence that indicates that the postendocytic alterations of the acid hydrolase molecules occur at a site through which the enzymes pass en route to the lysosomal compartment. Mouse L-cells incubated at 20 degrees C with beta-glucuronidase (isolated from mouse macrophage secretions) internalize the enzyme in a process that is inhibited by Man 6-P but unaffected by cycloheximide. As such, the linear accumulation of the ligand observed at 20 degrees C appears to occur through the continued recycling of the cell surface Man 6-P receptor. The subcellular distribution of the internalized ligands was assessed after homogenization of the cells and fractionation of the extracts by density gradient centrifugation. In contrast to the accumulation of the ligand within lysosomes at 37 degrees C, the beta-glucuronidase molecules internalized by the L cells at 20 degrees C accumulate within a population of vesicles that sediment at the same density as endocytic vesicles. Biochemical analysis of the internalized ligands indicates that: (a) the subunit molecular mass of both beta-glucuronidase and beta-galactosidase decrease upon cell association relative to the input form of the enzymes, and (b) the beta-glucuronidase molecules experience a limited dephosphorylation such that high-mannose-type oligosaccharides containing two phosphomonoesters are converted to single phosphomonoester forms. The same two post-endocytic alterations occur after the internalization of beta-glucuronidase by human I-cell disease fibroblasts, despite the low acid hydrolase content of these cells. The results indicate, therefore, that acid hydrolases internalized via the Man 6-P receptor are processed within the endocytic compartment. In that endogenous newly synthesized acid hydrolases display similar alterations during their maturation, the results further suggest that the endosomal compartment is involved in the sorting of ligands transported via both the cell surface and intracellular Man 6-P receptor.

scholarly journals Serum factors alter the extent of dephosphorylation of ligands endocytosed via the mannose 6-phosphate/insulin-like growth factor II receptor.

1989 ◽  
Vol 109 (3) ◽  
pp. 1037-1046 ◽  
Author(s):  
R Einstein ◽  
C A Gabel
Keyword(s):  
Growth Factor ◽  
High Density ◽  
Low Density ◽  
Insulin Like Growth Factor ◽  
Acid Hydrolases ◽  
Serum Factors ◽  
Serum Free ◽  
L Cells ◽  
Density State ◽  
Mannose 6 Phosphate

Mouse L-cells that contain the cation-independent (CI) mannose 6-phosphate (Man 6-P)/insulin-like growth factor (IGF) II receptor endocytose acid hydrolases and deliver these enzymes to lysosomes. The postendocytic loss of the Man 6-P recognition marker from the cell-associated acid hydrolases was assessed by CI-Man 6-P receptor affinity chromatography. 125I-labeled acid hydrolases internalized by L-cells grown at high density were delivered to lysosomes but were not dephosphorylated. In contrast, the same 125I-labeled hydrolases internalized by L-cells maintained at low density were delivered to lysosomes and were extensively dephosphorylated. The dephosphorylation at low density required 5 h for completion suggesting that the phosphatase responsible for the dephosphorylation is located within the lysosomal compartment. Transition from the high to low density state was rapid and was not inhibited by cycloheximide. Medium substitution experiments indicated that serum factors were necessary to maintain the L-cells in the dephosphorylation-competent (low density) state, and that serum-free conditions led to a dephosphorylation-incompetent (high density) state. Addition of IGF II to cells in serum-free medium allowed acid hydrolases subsequently introduced by endocytosis to be dephosphorylated. The results indicate that the removal of the Man 6-P recognition marker from endocytosed acid hydrolases is regulated by serum factors in the growth medium, including IGF II.

scholarly journals Enhancement of elastin expression by transdermal administration of sialidase isozyme Neu2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Akira Minami ◽  
Yuka Fujita ◽  
Jun Goto ◽  
Ayano Iuchi ◽  
Kosei Fujita ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Skin Diseases ◽  
Lower Layer ◽  
Elastic Fiber ◽  
Sialic Acid Residue ◽  
Elastic Fibers ◽  
Transdermal Administration ◽  
Sialidase Activity ◽  
Fiber Assembly ◽  
Senescence Accelerated Mice

AbstractReduction of elastin in the skin causes various skin diseases as well as wrinkles and sagging with aging. Sialidase is a hydrolase that cleaves a sialic acid residue from sialoglycoconjugate. Cleavage of sialic acid from microfibrils by the sialidase isozyme Neu1 facilitates elastic fiber assembly. In the present study, we showed that a lower layer of the dermis and muscle showed relatively intense sialidase activity. The sialidase activity in the skin decreased with aging. Choline and geranate (CAGE), one of the ionic liquids, can deliver the sialidase subcutaneously while maintaining the enzymatic activity. The elastin level in the dermis was increased by applying sialidase from Arthrobacter ureafaciens (AUSA) with CAGE on the skin for 5 days in rats and senescence-accelerated mice prone 1 and 8. Sialidase activity in the dermis was considered to be mainly due to Neu2 based on the expression level of sialidase isozyme mRNA. Transdermal administration of Neu2 with CAGE also increased the level of elastin in the dermis. Therefore, not only Neu1 but also Neu2 would be involved in elastic fiber assembly. Transdermal administration of sialidase is expected to be useful for improvement of wrinkles and skin disorders due to the loss of elastic fibers.

scholarly journals Porcine Arterivirus Infection of Alveolar Macrophages Is Mediated by Sialic Acid on the Virus

2004 ◽  
Vol 78 (15) ◽  
pp. 8094-8101 ◽  
Author(s):  
Peter L. Delputte ◽  
Hans J. Nauwynck
Keyword(s):  
Sialic Acid ◽  
Alveolar Macrophages ◽  
Sialic Acids ◽  
Respiratory Syndrome Virus ◽  
Specific Monoclonal Antibody ◽  
Neuraminidase Treatment ◽  
Acid Binding Protein ◽  
Sialic Acid Binding ◽  
High Mannose ◽  
Binding Lectin

ABSTRACT Recently, we showed that porcine sialoadhesin (pSn) mediates internalization of the arterivirus porcine reproductive and respiratory syndrome virus (PRRSV) in alveolar macrophages (Vanderheijden et al., J. Virol. 77:8207-8215, 2003). In rodents and humans, sialoadhesin, or Siglec-1, has been described as a macrophage-restricted molecule and to specifically bind sialic acid moieties. In the current study, we investigated whether pSn is a sialic acid binding protein and, whether so, whether this property is important for its function as a PRRSV receptor. Using untreated and neuraminidase-treated sheep erythrocytes, we showed that pSn binds sialic acid. Furthermore, pSn-specific monoclonal antibody 41D3, which blocks PRRSV infection, inhibited this interaction. PRRSV attachment to and infection of porcine alveolar macrophages (PAM) were both shown to be dependent on the presence of sialic acid on the virus: neuraminidase treatment of virus but not of PAM blocked infection and reduced attachment. Enzymatic removal of all N-linked glycans on the virus with N-glycosidase F reduced PRRSV infection, while exclusive removal of nonsialylated N-linked glycans of the high-mannose type with endoglycosidase H had no significant effect. Free sialyllactose and sialic acid containing (neo)glycoproteins reduced infection, while lactose and (neo)glycoproteins devoid of sialic acids had no significant effect. Studies with linkage-specific neuraminidases and lectins indicated that α2-3- and α2-6-linked sialic acids on the virion are important for PRRSV infection of PAM. From these results, we conclude that pSn is a sialic acid binding lectin and that interactions between sialic acid on the PRRS virion and pSn are essential for PRRSV infection of PAM.

scholarly journals Differential Glycosylation Between Recombinant Factor VIII Produced in Baby Hamster Kidney and Chinese Hamster Ovary Cells Confers Differences in Immunogenicity in a Humanized Hemophilia Α Mouse Model

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 326-326 ◽  
Author(s):  
Jesse Lai ◽  
Laura L Swystun ◽  
Dominique Cartier ◽  
Cunjie Zhang ◽  
Kate Nesbitt ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Factor Viii ◽  
Research Funding ◽  
Clinical Evidence ◽  
Lectin Binding ◽  
Chinese Hamster ◽  
Specific Igg ◽  
Ifn Γ ◽  
High Mannose

Abstract Introduction The formation of factor VIII (FVIII)- neutralizing antibodies is the most critical complication in the treatment of hemophilia A (HA). Recent clinical evidence suggests that recombinant FVIII (rFVIII) produced in baby hamster kidney (BHK-rFVIII) cells is more immunogenic than that produced in Chinese hamster ovary (CHO-rFVIII) cells. This difference in FVIII immunogenicity may be attributed to differences in protein glycosylation, which can impact the removal of FVIII from circulation through mechanisms leading to clearance and antigen presentation. Here, we document significant differences among the 25 potential N-linked glycans between these products, and we provide in vivo animal model-based evidence that supports these clinical observations. Methods Factor VIII lectin binding was assessed by ELISA to detect exposed glycans. Commercially-available rFVIII products were adsorbed at 1 ug/mL and specific glycan moieties were detected using a panel of biotinylated lectins and HRP-conjugated streptavidin. Confirmation of differences and determination of N-linked glycan structures was conducted by LC-MS/MS. Eight to 12 week old transgenic C57BL/6 HA mice were used in these studies. This model contains a murine f8 exon 16 KO and additionally harbors a human F8 transgene with a R593C point mutation. While these mice have undetectable plasma levels of human FVIII antigen and activity, they are tolerant to intravenously infused human rFVIII. Clearance was assessed following a 6 IU (~240 IU/kg) infusion of each rFVIII product, and FVIII activity was measured by chromogenic assay and normalized to a 5-minute time point. The number of interferon (IFN)-γ secreting splenocytes from rFVIII-primed naïve mice was determined by ELISPOT. FVIII immune responses were elicited by subcutaneous infusion (6 IU twice-weekly for 2 weeks) and adjuvant-coupled intravenous infusion (1 ug lipopolysacharride with the first infusion as described above) with either rFVIII product. Week 5 plasma samples were assessed for FVIII-specific IgG by ELISA, and FVIII inhibitors by one-stage clotting assay. Results Lectin binding showed that rFVIII produced in BHK cell lines exhibit lower proportions of high-mannose glycans (p<0.01), and greater levels of sialic acid capping (p<0.01) and fucosylated glycans (p<0.01). Mass spectra confirmed higher levels of sialic acid and identified two additional N-linked sites bearing high mannose glycans on CHO-rFVIII. In this mouse model we observed that BHK-rFVIII had a circulating half-life of 6.06 hours compared to the 10.01 hour half-life of CHO-rFVIII (p<0.0001). The immunogenicity of the BHK- and CHO-rFVIII products was next evaluated in vivo. In mice primed with a single 6 IU dose of BHK-rFVIII, we identified a higher proportion of FVIII-specific IFN-γ secreting splenocytes after seven days. Furthermore, long-term studies showed that 100% of mice subcutaneously exposed to BHK-rFVIII developed anti-FVIII IgG compared to the 47% that received CHO-rFVIII (p<0.01). Coincidently, when FVIII inhibitors were measured, we observed an incidence of 100% vs 37% (p<0.01), respectively. While the titres of FVIII-specific IgG were higher in mice exposed to BHK-rFVIII (p<0.01), there were no significant differences in the inhibitor concentrations. Similarly, we observed increased titres of FVIII-specific IgG in mice exposed intravenously (1 ug LPS with the first infusion) to BHK-rFVIII compared to CHO-rFVIII. However, there were no differences in the incidence of FVIII-specific IgG, nor in the incidence and concentration of inhibitors between the intravenously-infused mice. Conclusions Our results demonstrate that BHK-rFVIII exhibits altered pharmacokinetic and immunogenic properties compared to CHO-rFVIII in humanized hemophilia A mice. The observed early increase in the proportion FVIII-specific IFN-γ producing cells in the spleen suggests an intrinsic immunogenic element of BHK-rFVIII. Similarly, the substantially increased immunogenicity of BHK-rFVIII in mice when treated subcutaneously complements the previously-reported clinical evidence. These differences may be attributed to the significant disparities in N-linked glycosylation, most notably high mannose and sialic acid containing glycans. Additional studies are underway to directly address the role of the these specific glycans and their potential impact on immunogenicity of rFVIII. Disclosures Lillicrap: Octapharma: Research Funding; Baxalta: Research Funding; Biogen-Idec: Research Funding; Bayer: Research Funding.

scholarly journals MALDI TIMS IMS of Disialoganglioside Isomers – GD1a and GD1b in Murine Brain Tissue

2021 ◽  
Author(s):  
Katerina Djambazova ◽  
Martin Dufresne ◽  
Lukasz Migas ◽  
Angela Kruse ◽  
Raf Van de Plas ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Phase Separation ◽  
Sialic Acid ◽  
Gas Phase ◽  
Sialic Acid Residue ◽  
Spinal Cord Tissue ◽  
Total Ganglioside ◽  
Tissue Sections ◽  
Maldi Ims ◽  
Gas Phase Separation

Gangliosides are classified as acidic glycosphingolipids, containing ceramide moieties and oligosaccharide chains with one or multiple sialic acid residue(s). The presence of multiple sialylation sites gives rise to highly diverse isomeric structures with distinct biological roles. Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) enables the untargeted spatial analysis of gangliosides, among other biomolecules, directly from tissue sections. Integrating trapped ion mobility mass spectrometry (TIMS), a gas-phase separation technology, with MALDI IMS allows for the investi-gation of isomeric lipid structures in situ. Here we demonstrate the gas-phase separation of disialoganglioside isomers GD1a and GD1b that differ in the position of a sialic acid residue, in a standard mixture of both isomers, a total ganglioside extract, and directly from thin tissue sections. The unique spatial distributions of GD1a/b (d36:1) and GD1a/b (d38:1) were deter-mined from rat hippocampus, as well as in a spinal cord tissue section.

scholarly journals Azurophilic Granules of Human Neutrophilic Leukocytes Are Deficient in Lysosome-Associated Membrane Proteins but Retain the Mannose 6-Phosphate Recognition Marker

Blood ◽  
1998 ◽  
Vol 91 (3) ◽  
pp. 1044-1058 ◽  
Author(s):  
A.-M. Cieutat ◽  
P. Lobel ◽  
J.T. August ◽  
L. Kjeldsen ◽  
H. Sengeløv ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Lysosomal Enzymes ◽  
Acid Hydrolases ◽  
Structural Localization ◽  
Dense Bodies ◽  
Neutrophilic Leukocytes ◽  
Azurophil Granule ◽  
Membrane Bound ◽  
Storage Granules ◽  
Mannose 6 Phosphate

Abstract During granulocyte differentiation in the bone marrow (BM), neutrophilic leukocyte precursors synthesize large amounts of lysosomal enzymes. These enzymes are sequestered into azurophilic storage granules until used days later for digestion of phagocytized microorganisms after leukocyte emigration to inflamed tissues. This azurophil granule population has previously been defined as a primary lysosome, ie, a membrane-bound organelle containing acid hydrolases that have not entered into a digestive event. In this study, azurophil granules were purified and shown to contain large amounts of mannose 6-phosphate-containing glycoproteins (Man 6-P GP) but little lysosome-associated membrane proteins (LAMP). In addition, the fine structural localization of Man 6-P GP and LAMP was investigated at various stages of maturation in human BM and blood. Man 6-P GP were present within the azurophilic granules at all stages of maturation and in typical multivesicular bodies (MVB) as well as in multilaminar compartments (MLC), identified by their content of concentric arrays of internal membranes. LAMP was absent in all identified granule populations, but was consistently found in the membranes of vesicles, MVB, and MLC. The latter compartment has not been previously described in this cell type. In conclusion, the azurophilic granules, which contain an abundance of lysosomal enzymes and Man 6-P GP, lack the LAMP glycoproteins. By current criteria, they therefore cannot be classified as lysosomes, but rather may have the functional characteristics of a regulated secretory granule. Rather, the true lysosomes of the resting neutrophil are probably the MVB and MLC. Finally, the typical “dense bodies” or mature lysosomes described in other cells are not present in resting neutrophils.

scholarly journals Chlamydia pneumoniae Uses the Mannose 6-Phosphate/Insulin-Like Growth Factor 2 Receptor for Infection of Endothelial Cells

2005 ◽  
Vol 73 (8) ◽  
pp. 4620-4625 ◽  
Author(s):  
Mirja Puolakkainen ◽  
Cho-Chou Kuo ◽  
Lee Ann Campbell
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Chlamydia Trachomatis ◽  
Membrane Protein ◽  
Outer Membrane Protein ◽  
Chlamydia Pneumoniae ◽  
Insulin Like Growth Factor ◽  
Inhibition Assay ◽  
High Mannose ◽  
Mannose 6 Phosphate

ABSTRACT Several mechanisms for attachment and entry of Chlamydia have been proposed. We previously determined that the major outer membrane protein of Chlamydia trachomatis is glycosylated with a high-mannose oligosaccharide, and a similar structure inhibited the attachment and infectivity of C. trachomatis in epithelial cells. Because insulin-like growth factor 2 (IGF2) was shown to enhance the infectivity of Chlamydia pneumoniae but not C. trachomatis in endothelial cells, a hapten inhibition assay was used to analyze whether the mannose 6-phosphate (M6P)/IGF2 receptor that also binds M6P could be involved in infection of endothelial cells (HMEC-1) by Chlamydia. M6P and mannose 6-phosphate-poly[N-(2-hydroxyethyl)-acrylamide] (M6P-PAA) inhibited the infectivity of C. pneumoniae AR-39, but not C. trachomatis serovar UW5 or L2, while mannan inhibited the growth of C. trachomatis, but not C. pneumoniae. Using metabolically labeled organisms incubated with cells at 4°C (organisms attach but do not enter) or at 37°C (organisms attach and are internalized), M6P-PAA was shown to inhibit attachment and internalization of C. pneumoniae in endothelial cells but did not inhibit attachment or internalization of C. trachomatis serovar E or L2. These findings indicate that C. pneumoniae can utilize the M6P/IGF2 receptor and that the use of this receptor for attachment and entry differs between C. pneumoniae and C. trachomatis.

A phenolic–taxometric study of Medicago (Leguminosae)

1982 ◽  
Vol 60 (12) ◽  
pp. 2477-2495 ◽  
Author(s):  
D. Classen ◽  
C. Nozzolillo ◽  
E. Small
Keyword(s):  
Leaf Tissue ◽  
Single Species ◽  
Interspecific Variation ◽  
Intraspecific Diversity ◽  
Two Dimensional ◽  
Annual Species ◽  
Taxonomic Analysis ◽  
Morphological Criteria ◽  
Phenolic Profiles ◽  
The One

Phenolics from dried leaf tissue of 47 species of Medicago were examined using two-dimensional chromatography on polyamide plates. A few samples from the closely related genera Melilotus and Trigonella were also studied. Compounds tentatively identified as cyanidin, quercetin, kaempferol, luteolin, apigenin, chrysoeriol, tricin, and coumestrol were found. Proanthocyanidins were not detected in the leaf tissue of any of the species. Apigenin was found in all species of Medicago except M. cretacea but not in the one species of Melilotus or the two of Trigonella studied. Two additional compounds as yet unidentified were also restricted to Medicago. All of the phenolics were detected as aglycones with the possible exceptions of glucuronides and C-glycosides which are strongly resistant to hydrolysis. Data for the phenolic compounds were subjected to numerical taxonomic analysis. The single species of Melilotus and the two species of Trigonella were dramatically different from Medicago in their phenolic composition. A number of controversial species placed in Medicago by some taxonomists, and in Trigonella by others, proved to have phenolic profiles much like Medicago and quite unlike the species of Trigonella examined. The annual species comprising subgenus Spirocarpos, which are morphologically distinct from the remaining species of Medicago, were not clearly distinguishable from the other species collectively on the basis of phenolic chemistry. However, within subgenus Spirocarpos the most sharply distinguished subgroup on morphological criteria, section Pachyspirae, tended to be different chemically from the remaining species of the subgenus. When the species of Medicago except for subgenus Spirocarpos were analysed separately, it was found that the two major phylads of these tended to be distinguishable chemically. These included a group of perennials (subgenus Medicago section Falcago) and a group of peculiar species (subgenus Orbicularia) tending morphologically towards the genus Trigonella). Appreciable intraspecific diversity was found for phenolic chemistry but significantly less than interspecific variation. In a few cases species which are quite similar morphologically diverged chemically, most notably the two species of subgenus Lupularia.

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