Isozyme Profiles Research Articles

Ultraviolet radiation-induced melanogenesis in human melanocytes. Effects of modulating protein kinase C.

The mechanism by which ultraviolet radiation induces melanogenesis in epidermal melanocytes is unknown. Previous observations that in cultured human melanocytes 1-oleoyl-2-acetylglycerol augmented both basal and ultraviolet radiation-induced melanogenesis, suggested that the responses were mediated via protein kinase C. However, paradoxically the phorbol ester TPA was without effect. Therefore, the present study has examined the involvement of protein kinase C in melanogenesis. Analysis of the isozyme profile of human melanocytes revealed the presence of protein kinase C alpha, beta I, epsilon and zeta but not the isozyme eta. Following exposure to 500 nM TPA for 24 hours, isozymes alpha, beta I and epsilon were downregulated, but zeta was unaffected. Similar isozyme profiles were observed in S91 and SKMEL3 melanoma cells. The melanogenic responses to 1-oleoyl-2-acetylglycerol and ultraviolet radiation were unaffected by inhibition of protein kinase C with Ro31-8220, or ablation by downregulation with 500 nM TPA, in human melanocytes and melanoma cells. 1-Oleoyl-2-acetylglycerol had no effect on protein kinase C activity in human melanocytes, as measured by rapid phosphorylation of the 80 kDa protein myristoylated alanine-rich C kinase substrate (MARCKS). Ultraviolet radiation induced a small increase in MARCKS protein phosphorylation but this effect was inhibited by pretreatment for 24 hours with 500 nM TPA, which had no effect on ultraviolet-induced melanogenesis. Overall, these findings indicate that 1-oleoyl-2-acetylglycerol and ultraviolet radiation activate melanogenesis via protein kinase C-independent pathways.

Influence of Nitrogen Source on the Growth, Prolamin Content, and Glutamine Synthetase Isozyme Profiles of Endosperm-Derived Suspension Cultures of Maize

Summary In order to assess the suitability of endosperm-derived suspension cultures (EDSC) as a model system for nitrogen metabolism in intact maize kernel endosperm, the isozym complements of glutamine synthetase (GS), a key enzyme of nitrogen metabolism in higher plants, were compared from both tissue sources. Anion exchange profiles revealed five GS isozymes from intact endosperm. These same isozymes were also found in EDSC, although in very different relative proportions, along with a sixth isozyme with elution characterestics corresponding to the chloroplast GS from maize leaves. Isoelectric focusing under denaturing conditions followed by immunoblotting revealed the presence of five GS subunits from intact endosperm changed strikingly with development. Developmental changes in the isozyme patterns were less dramatic in the EDSC. Culturing the EDSC on alternative nitrogen sources changed the relative proportions of isozymes and affected growth and zein accumulation. It was concluded that while the EDSC do resemble intact endosperm in that they express the same GS subunits, the differences in the relative proportions of those subunits and the corresponding isozymes and differences in developmental changes make extrapolations of results obtained from studies of nitrogen metabolism using the endosperm suspension cultures to the intact endosperm inappropriate.

Somatic Hybridization of Complementary Citrus Rootstock:Five New Hybrids

Protoplasm culture following polyethylene glycol-induced fusion resulted in the regeneration of tetraploid somatic hybrid plants from the following attempted parental combinations: Cleopatra mandarin (Citrus reticulata Blanco) + Argentine trifoliate orange [Poncirus trifoliata (L.) Raf.]; `Succari' sweet orange [C. sinensis (L.) Osb.] + Argentine trifoliate orange; sour orange (C. aurantium L.) + Flying Dragon trifoliate orange (P. trifolita); sour orange + Rangpur (C. limonia Osb.); and Milam lemon (purported sexual hybrid of C. jambhiri Lush × C. sinensis) + Sun Chu Sha mandarin (C. reticulate Blanco). Protoplasm isolation, fusion, and culture were conducted according to previously published methods. Regenerated plants were classified according to leaf morphology, chromosome number, and peroxidase, phosphoglucomutase, and phosphoglucose isomerase leaf isozyme profiles. All of the somatic hybrid plants were tetraploid, as expected (2n = 4x = 36), and all five selections have been propagated and entered into commercial citrus rootstock trials.

Shortening velocity and ATPase activity of rat skeletal muscle fibers: effects of endurance exercise training.

Mechanical properties were measured in single skinned fibers from rat hindlimb muscle to test the hypothesis that the fast type IIb fiber exhibits a higher maximal shortening velocity (Vo) than the fast type IIa fiber and that the difference is directly attributable to a higher myofibrillar adenosinetriphosphatase (ATPase) activity in the type IIb fiber. Additional measurements were made to test the hypotheses that regular endurance exercise increases and decreases the Vo of the type I and IIa fiber, respectively, and that the altered Vo is associated with a corresponding change in the fiber ATPase activity. Rats were exercised by 8-12 wk of treadmill running for 2 h/day, 5 day/wk, up a 15% grade at a speed of 27 m/min. Fiber Vo was determined by the slack test, and the ATPase was measured fluorometrically in the same fiber. The myosin isozyme profile of each fiber was subsequently determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The mean +/- SE Vo (7.9 +/- 0.22 fiber lengths/s) of the type IIb fiber was significantly greater than the type IIa fiber (4.4 +/- 0.21 fiber lengths/s), and the higher Vo was associated with a higher ATPase activity (927 +/- 70 vs. 760 +/- 60 microM.min-1.mm-3). The exercise program induced cardiac hypertrophy and an approximately twofold increase in the mitochondrial marker enzyme citrate synthase. Exercise had no effect on fiber diameter or peak tension per cross-sectional area in any fiber type, but, importantly, it significantly increased (23%) both the Vo and the ATPase activity of the slow type I fiber of the soleus.(ABSTRACT TRUNCATED AT 250 WORDS)

Loss of protein kinase C δ isozyme immunoreactivity in human adenocarcinomas

Protein kinase C (PKC) has been implicated in the control of colonic epithelial proliferative activity and in the process of malignant transformation. In the present study, we assessed by histone IIIS phosphorylation in vitro, total PKC activity, and the subcellular distribution of this activity in human adenocarcinomas and surrounding uninvolved mucosa from six patients. In these same tissues, we also examined the isozyme profile of PKC by immunoblotting. Total PKC activity and the subcellular distribution of PKC activity was not significantly different in mucosa compared to corresponding values in the tumors. Extracts of both human mucosa and tumors reacted with antibody to PKC isozymes alpha, beta, delta and zeta but did not react with antibody to the gamma and epsilon isozymes. The antibodies employed were directed against rabbit brain PKC (alpha, beta, gamma) or peptide sequences deduced from rat cDNA (gamma, delta, epsilon, and zeta). Accordingly, the apparent absence of the epsilon isozyme in human mucosa and adenocarcinoma may be due to failure to conserve the relevant sequence rather than to loss of the isozyme per se. No statistically significant differences were noted in subcellular distribution of any of the isozymes in the tumors compared to mucosa. However, the subcellular distribution of the delta isozyme was highly variable in the tumors. Total PKC beta immunoreactivity and that of the soluble, but not particulate, fraction were both significantly lower in homogenates of adenocarcinomas compared to corresponding values in surrounding mucosa, when expressed as a function of protein. However, these differences in PKC beta were abolished when results were expressed as a function of tissue DNA content.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde dehydrogenase involvement in a variant of the brown Norway rat acute myelocytic leukaemia (BNML) that acquired cyclophosphamide resistance in vivo

The development of drug resistance is an important factor contributing to failure of chemotherapy in cancer patients. Cyclophosphamide (CP) is a cytostatic drug widely used in the treatment of haematological malignancies and solid tumours. Because CP requires bioactivation to become cytotoxic, an in vivo approach was chosen to generate a subline of the Brown Norway rat acute myelocytic leukaemia (BNML/CPR) highly resistant to CP to serve as a model to investigate the molecular mechanism(s) of cyclophosphamide resistance. The role of the CP-detoxifying enzyme aldehyde dehydrogenase (ALDH) in the molecular mechanism of CP resistance in this subline of the BNML has been investigated. Compared to the parent BNML cell line, the BNML/CPR cell line displayed an approximately 6-fold higher level of ALDH enzyme activity. Pretreatment of leukaemic rats with the ALDH inhibitor disulfiram resulted in a restoration of CP sensitivity of animals carrying the BNML/CPR cells. Furthermore, in vitro incubation of BNML/CPR cells with disulfiram prior to incubation with the activated CP derivative mafosfamide resulted in an extra 2–3 log cell kill as indicated by the survival time of rats which were injected with disulfiram pretreated BNML/CPR cells compared to non-pretreated BNML/CPR cells. Data on the glutathione S-transferases (GSTs) isozyme profiles of cytoplasmic liver and spleen extracts of BNML- and BNML/CPR-carrying leukaemic rats indicated that the total GST enzyme amount was lower in BNML/CPR cells than in parent BNML cells. Furthermore, the BNML/CPR subline proved to be sensitive to phosphoramide mustard, both in vivo and in vitro.

Host effects on glutathione S-transferase activity in Fasciola hepatica

Glutathione S-transferases (GST, E.G. 2.5.1.18) in Fasciola hepatica from sheep were previously found to be extremely variable with regard to specific GST activity and isoenzyme profile within and between parasite isolates. The effect of the host on GST activity and isoenzyme profile was examined by infecting mice, rats and cattle as well as sheep with one or the other of two isolates—either salicylanilide-resistant or salicylanilide-susceptible F. hepatica. In the case of both isolates, GST activity in hosts relatively resistant to reinfection—rats and cattle—was lower and more restricted in range compared with hosts susceptible to multiple infection—mice and sheep. In the case of the rat flukes, there was little variation in isozyme profiles whereas cattle flukes appeared to exhibit more variation than sheep flukes. In mice, despite the apparent variability in GST activity, only one GST band was found in the isoenzyme profiles. Therefore, the host appears to exert a pronounced effect on the activity and expression of GSTs in F. hepatica which may be related to variation in the immune responses of the different hosts during infection.

Glutathione S-transferases in the organ of Corti of the rat: Enzymatic activity, subunit composition and immunohistochemical localization

Glutathione S-transferases (GSTs), a family of ubiquitous cytosolic isozymes, catalyze the detoxification of electrophilic substrates with reduced glutathione and participate in intracellular binding and transport of lipophilic substances. This study measured GST activity biochemically in the inner ear of the rat; determined the isozyme profile by Western blotting; and identified, immunohistochemically. the distribution of the μ and π class GSTs in the organ of Corti. GST enzymatic activity in inner ear tissues ranged from 117 to 348 nmoles glutathione converted/min/mg protein, values somewhat higher than those found in brain (130) and much lower than in liver (1011). Of the GST isoforms, the π class (identified by antibodies against the Y p subunit) was most prominent, the μ class (Y b1 subunit) clearly evident while the α class (Y a subunit) was barely detectable on Western blots. Immunocytochemical analysis showed differential distribution of the Y h1 and Y p subunits. The Y b1 subunit was present in the sensory cells, while supporting cells were not specifically stained. At the subcellular level, the isozyme was localized in the apical zones of inner (IHCs) and outer hair cells (OHCs) close to the cuticular plate. The extent of staining, however, varied between OHCs and IHCs. In the OHCs, staining appeared in discrete spots in the apical areas only, whereas in IHCs staining extended further towards the center of the cells. The Y p subunit was mainly localized to Deiters cell processes and pillar cells. Both Y b1 and Y p colocalized with tubulin-specific antibody. The functional significance of GST in the cochlear receptor cells is speculative. However, a role anologous to that in other tissues (detoxification, prostaglandin synthesis) can be assumed. In addition, an association of GST with the microtubule system is possible based on immunohistochemical colocalization with tubulin.

A Comparison of α-Amylase Isozyme Profiles in Selected Su and High-Sugar Sweet Corn (sh-2, su-1, su-1 se) Lines (Zea mays L.)

α-Amylases were purified from germinating starchy (Su) maize kernels (Funks G4646) using glycogen precipitation and preparative SDS-PAGE. Antiserum to the purified α-amylases was produced in rabbits. Isozymes of α-amylase from the scutellum and aleurone tissues of kernels of five Su lines were compared with a sweet corn (su-1) and two high-sugar sweet corn (su-1 se and sh-2) inbred lines in the same genetic background, using isoelectric focusing gels, starch zymograms, and immunoblotting analyses. The most notable differences were found in the high-sugar sweet corn kernels. In the sh-2 aleurone, there were no α-amylase isozymes detected on the zymogram and immunoblot, indicating a lack of enzyme accumulation. In the su-1 se scutellum, there were fewer isozymes compared with most of the lines examined, but the significance of this is not clear. Comparison of the five Su lines revealed several isozymes common to all the kernels examined, but there were considerable tissue-specific differences in the number of isozymes between the aleurone and scutellum tissues. The Funks G4646 (Su) and RB-4 (Su) had similar scutellar and aleurone isozyme patterns, with the aleurone having one more isozyme than the scutellum. In OH43 (Su) kernels, the scutellum had one to two more isozymes with α-amylase activity than the aleurone, while the IL451b (Su) scutellum had fewer isozymes (seven to eight) than the aleurone (14-16). Both high- and low-pI isozymes of wheat and barley, and the low-pI isozymes of rice, were recognized by the antibodies to maize α-amylases developed in this study. These data indicate a complex relationship between the carbohydrate and sugar composition of the kernel and the synthesis of α-amylase isozymes during germination.

Effects of female hormones and 3,5,3'-triiodothyronine or dexamethasone on induction of epidermal growth factor and proteinases F, D, A, and P in the submandibular glands of hypophysectomized male mice.

The effects of progesterone (Pro), 5 alpha-dihydrotestosterone (DHT), 17 beta-estradiol (E2), T3, and dexamethasone (Dex), given alone or in combination, on induction of epidermal growth factor (EGF) and proteinase isozymes in the submandibular glands of hypophysectomized mice were examined. Each hormone, except E2, acting alone had essentially comparable inductive effects on EGF concentrations and on total proteinase activity. E2 alone had no inductive effect at all. Pro acted synergistically with T3, but its inductive effect was diminished when given with Dex. E2 was not synergistic with T2, and it inhibited the effect of Dex; it also partially blocked the action of DHT on induction of proteinase activity but not of EGF. Simultaneous administration of all five hormones restored total proteinase activity completely but EGF levels to only 50% of values for intact males, respectively. Submandibular proteinases were resolved by isoelectric focusing into four isozymes: proteinase F (pI 4.8), proteinase D (pI 5.8), proteinase A (pI 6.2), and proteinase P (pI 10.0). Pro alone slightly increased levels of proteinase F but greatly raised levels of the other three isozymes. This inductive action was augmented when Pro was given with T3 but blocked when it was given with Dex. E2 alone not only failed to induce any of the isozymes, but even further reduced levels of proteinase F. It also decreased the inductive effects of T3 on these isozymes, and with Dex completely blocked induction of proteinases D, A, and P. E2 plus DHT suppressed proteinase F levels and only induced proteinase A. All five hormones together reestablished the isozyme profile seen in intact males. These results show that Pro by itself is as capable as androgens, thyroid hormone, or glucocorticoid in regulating expression of these submandibular polypeptides, and that its action can be modulated by other pituitary-dependent hormones. In addition, they demonstrate that E2 does not regulate their expression, and that it has an inhibitory effect on the inductive action of other hormones. Last, they indicate that these various hormones may regulate expression of EGF and of each of the individual proteinase isozymes differently.

Hypoxic metabolism in wild rice (Zizania palustris): enzyme induction and metabolite production

Alcohol dehydrogenase (ADH, EC 1. 1. 1. 1), lactate dehydrogenase (LDH, EC 1. 1. 1. 27) and alanine aminotransferase (AlaAT, EC 2. 6. 1. 2) activity in wild rice (Zizania palustris L.) root tissue increased after 4 days of exposure to hypoxic stress. The activities of ADH and AlaAT also increased in leaf tissue under these same conditions, whereas LDH activity did not. Isozyme banding patterns indicate that wild rice has at least two functional Adh genes, only one of which is hypoxically induced in root and leaf tissue. The isozyme profile of LDH also indicates the presence of two functional Ldh genes in wild rice. Two bands of AlaAT activity are visible on native electrophoretic gels of root and leaf tissue. Neither of these bands appears to increase in activity in hypoxic samples, even though spectrophotometric assays indicate an increase in AlaAT activity. Ethanol accumulation was the highest of all the metabolites measured. Alanine and malate also accumulated under hypoxic conditions but only to about one‐fifth the level of ethanol. Succinate, aspartate and lactate showed no observable changes throughout the induction period. These results show that wild rice differs from domesticated rice (Oryza sativa L.) in its metabolic responses to anaerobic stress. The possible role of these responses in conferring flood tolerance is discussed.

Effects of female hormones and 3,5,3'-triiodothyronine or dexamethasone on induction of epidermal growth factor and proteinases F, D, A, and P in the submandibular glands of hypophysectomized male mice

The effects of progesterone (Pro), 5 alpha-dihydrotestosterone (DHT), 17 beta-estradiol (E2), T3, and dexamethasone (Dex), given alone or in combination, on induction of epidermal growth factor (EGF) and proteinase isozymes in the submandibular glands of hypophysectomized mice were examined. Each hormone, except E2, acting alone had essentially comparable inductive effects on EGF concentrations and on total proteinase activity. E2 alone had no inductive effect at all. Pro acted synergistically with T3, but its inductive effect was diminished when given with Dex. E2 was not synergistic with T2, and it inhibited the effect of Dex; it also partially blocked the action of DHT on induction of proteinase activity but not of EGF. Simultaneous administration of all five hormones restored total proteinase activity completely but EGF levels to only 50% of values for intact males, respectively. Submandibular proteinases were resolved by isoelectric focusing into four isozymes: proteinase F (pI 4.8), proteinase D (pI 5.8), proteinase A (pI 6.2), and proteinase P (pI 10.0). Pro alone slightly increased levels of proteinase F but greatly raised levels of the other three isozymes. This inductive action was augmented when Pro was given with T3 but blocked when it was given with Dex. E2 alone not only failed to induce any of the isozymes, but even further reduced levels of proteinase F. It also decreased the inductive effects of T3 on these isozymes, and with Dex completely blocked induction of proteinases D, A, and P. E2 plus DHT suppressed proteinase F levels and only induced proteinase A. All five hormones together reestablished the isozyme profile seen in intact males. These results show that Pro by itself is as capable as androgens, thyroid hormone, or glucocorticoid in regulating expression of these submandibular polypeptides, and that its action can be modulated by other pituitary-dependent hormones. In addition, they demonstrate that E2 does not regulate their expression, and that it has an inhibitory effect on the inductive action of other hormones. Last, they indicate that these various hormones may regulate expression of EGF and of each of the individual proteinase isozymes differently.

Characterizing Isozymes of Spanish Cherimoya Cultivars

Isozymes have been used as genetic markers to characterize seven Spanish cherimoya (Annona cherimola Mill.) cultivars. Fifteen enzyme systems were analyzed. Ten varied [aconitase (ACO, EC 4.2.1.3), alcohol dehydrogenase (ADH, EC 1.1.1.1), glutamate oxalacetate transaminase (GOT, EC 2.6.1.1), isocitrate dehydrogenase (IDH, EC 1.1.1.42), leucine aminopeptidase (LAP, EC 3.4.11.1), malate dehydrogenase (MDH, EC 1.1.1.37), phosphoglucose isomerase (PGI, EC 5.3.1.9), phosphoghtcomutase (PGM, EC 2.7.5.1), shikimate dehydrogenase (SKDH, EC 1.1.1.25), and triose phosphate isomerase (TPI, EC 5.3.1.1)] and five did not [acid phosphatase (ACPH, EC 3.1.3.2), diaphorase (DIA, EC 1.6.4.3), malic enzyme (ME, EC 1.1.1.40), 6-phosphogluconic dehydrogenase (6PGDH, EC 1.1.1.44), and superoxide dismutase (SOD, EC 1.15.1.1)]. Two cultivars, Campa and Campa Mejorada, had identical banding patterns for all enzymes tested. All others were identified as distinct cultivars because of isozyme differences. The identical isozyme profiles of `Campa' and `Campa Mejorada' probably indicate that they are the same cultivar. A cluster analysis of isozyme profiles showed that Spanish cultivars were clearly different from Californian cultivars.

Characteristics of the Glutathione/Glutathione-S-Transferase Detoxification System in Melphalan Resistant Human Prostate Cancer Cells

Glutathione (GSH) and glutathione-S-transferases (GST) have been implicated in resistance of tumor cells to certain alkylating agents, including melphalan. Glutathione levels and GST activities were determined in melphalan-resistant sublines of the human prostate carcinoma cell lines DU 145, PC-3 and LNCaP produced by serial treatment with melphalan at progressively increasing concentrations. The resistant sublines M4.5DU145, M5DU145, M6DU145, M6PC-3 and M6LNCaP were 27-, 7-, 3-, 6- and 2-fold more resistant to melphalan than the parental lines. The melphalan-resistant DU 145 and PC-3 lines showed cross-resistance to cisplatin and tetraplatin, but retained sensitivity to vinblastine, colchicine and etoposide. Interestingly, both sublines were also resistant to methotrexate and adriamycin. The melphalan-resistant LNCaP line showed slight resistance to cisplatin and adriamycin, but remained sensitive to tetraplatin and methotrexate. This line also retained sensitivity to vinblastine while developing resistance to colchicine. Intracellular GSH levels were increased 2.8 fold for M5DU145, 1.7 fold for M6PC-3 and 2.1 fold for M6LNCaP compared to the parental lines, whereas GST activity using chlorodinitro-benzene as a substrate was comparable for all lines. When cumene hydroperoxide was used as a substrate, an increase in GST activity was noted only in the M6PC-3 line as compared with the parent line. Western blot analysis showed no change in GST isozyme profile between parent and resistant DU 145 lines; however a mu class isoenzyme was detected in the resistant, but not in the parent PC-3 line, using a Yb1 antibody. M5DU145 cells maintained in the absence of melphalan for seven months maintained their resistance to melphalan. Depletion of GSH, with buthionine sulfoximine, to control levels reversed melphalan resistance to control levels.

Does clonal fragmentation contribute to recruitment inFestuca novae-zelandiae?

Abstract The fragmentation of large tussocks into several independent plants has been suggested as being important to recruitment in F. novae-zelandiae populations. This study investigated this suggestion using isozyme electrophoresis to determine the identity of mapped tussocks. Of the plants electrophoretically surveyed, 58% shared their isozyme profile with at least one other plant. The maximum distance observed (2.68 m) between pairs of isozymically identical plants was consistent with the age of the grassland and observed rates of radial spread of adjacent tussocks. While complicating factors in methodology mean that these results overestimate the importance of clonal fragmentation, this process does occur in Festuca novae-zelandiae and contributes to the recruitment of new individuals. However, in light of the large number of plants with unique isozyme profiles, establishment from seed appears to be a more important source of recruits than clonal fragmentation in Festuca novae-zelandiae.

Peroxidase activities and isoenzyme profiles associated with development of avocado (Persea americana, M.) leaves at different ontogenetic stages

Changes in four peroxidase activity fractions (soluble, membrane-bound, as well as ionically and covalently bound) were studied during development of juvenile and adult avocado leaves. Greater differences were found in the soluble fraction with an increase in total activity at the end of the growth phase. In relation to the ontogenetic stages, there were significant variations in the soluble peroxidase activity of both stages, especially in leaves which have already detained their growth, 263 U/g fresh wt in adult leaves vs. 70 U/g fresh wt juvenile leaves. Moreover, the isozyme profile of this fraction revealed the appearance of an anionic band, Rf 0.35, at much earlier stages in juvenile than in adult leaves. Concerning the other three fractions, there were no marked changes in total activity of either membrane-bound or ionically and covalently bound peroxidases. However, in the isoenzyme profiles of the ionically bound fraction of juvenile leaves, three highly cationic bands appeared at much earlier stages than in adult leaves. In avocado, attempts to use leaf peroxidase activity as marker of ontogenetic age must be taken with caution, since great fluctuations related with developmental stages occur in juvenile and adult leaves.

The Relationship Between Norton and Cynthiana, Red. Wine Cultivars Derived fromVitis aestivalis

The similarity of grape cultivars Norton and Cynthiana was investigated via isozyme and botanical analyses. Five isozyme systems, MDH, GPI, DIAP, PGM, and LAP, presented identical banding patterns for two accessions of Cynthiana and for seven accessions of Norton. The color of the indument varied from white to rusty brown on shoot tips grown from cuttings, even within accessions. Plants with white shoot tips were infrequent. Pigmented shoot tips had the same isozyme profile as pigmentless shoot tips. No other significant morphological differences between the Norton and Cynthiana genotypes were noted. Norton and Cynthiana may be cultivars derived from the same clonal source.

Biochemical studies on palm pollen

Abstract Striking similarities and wide diversity in the phenolic compounds and isozyme profiles were recorded in the pollen grains of Phoenix sylvestris, Areca catechu and Cocos nucifera (Palmae). Morphologically, pollen grains of three species showed similar trends. The results of the chromatographic and electrophoretic studies were concordant with current systematic classification of Palmae.

SYSTEMATIC INFERENCES FROM VARIATION IN ISOZYME PROFILES OF ARCTIC AND ALPINE CESPITOSE FESTUCA (POACEAE)

Variation in isozyme patterns was used to assess species boundaries in North American arctic and alpine representatives of the Festuca ovina L. complex. Isozyme profiles, in combination with chromosome number, delimit four discrete entities within the complex: F. brevissima Jurtzev (diploid); F. aggr. auriculata Drobov (diploid); F. brachyphylla Schultes (hexaploid); and tetraploid populations corresponding in morphology to F. baffinensis Polunin (arctic Canada) and F. minutiflora Rydberg (alpine United States). Although no fixed difference was detected between isozyme profiles of the latter two taxa, they are morphologically distinct. Thus variation in isozymes, morphology, and chromosome number delimits five taxa within the F. ovina complex in North America. Some alleles observed in the polyploid taxa were not detected among the diploids, and some observed in F. brachyphylla, the hexaploid taxon, were not detected in either the diploid or the tetraploid species. One possible explanation for these occurrences is that the North American polyploids originated in Eurasia, where many other potential diploid and tetraploid progenitors occur.

Lentil domestication: On the quality of evidence and arguments

The current views on lentil domestication are based on biological attributes of the wild progenitorLens culinaris ssp. orientalis and on assumptions which have never been tested. Seed dormancy, a major factor in the adaptation of ssp.orientalis to its natural habitat, makes it inappropriate for cultivation, because poor germination causes seed yield following cultivation to be equal to the amount of sown seeds. Higher yield, resulting from the evolution of a non-dormant type can be obtained only after five or six cycles of unprofitable cultivation. It is doubtful that incipient farmers would have undertaken such an endeavor without preexisting knowledge that non-dormant types could eventually be obtained. Experiments involving the sowing of wild lentil would have been much more successful if the non-dormant types were present in appreciable quantities in the seed stock. Establishment of that type in the natural population would have required a period of seven to eight years with favorable growing conditions allowing the non-dormant type to become widespread in the population, followed by massive predation by man reducing the hazard of a population explosion. The close similarity between isozyme profiles of the cultivated lentil and its wild progenitor indicates that lentil cultivation was attempted with seeds derived from different populations and in different areas.