Orientador: Paulo Arruda / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-23T05:18:54Z (GMT). No. of bitstreams: 1 Dante_RicardoAugusto_M.pdf: 3047440 bytes, checksum: d07e6d661d90e857dc49807527d8c607 (MD5) Previous issue date: 1997 / Mestrado

Orientador : Paulo Arruda / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-15T02:13:30Z (GMT). No. of bitstreams: 1 Ottoboni_LauraMariaMariscal_D.pdf: 6659288 bytes, checksum: ba717d49a715af04e12989c18fe70d85 (MD5) Previous issue date: 1989 / Resumo: As proteinas da semente do Coix lacryma-jobi L. var. Adlay foram extraidas e caracterizadas. O endosperma do Adlay contem aproximadamente 21% de proteina. A principal fração proteica do endosperma do Adlay e uma prolamina denominada coixina, cuja porcentagem varia de 10,8% a 77,8%, dependendo da concentração de 2-ME utilizado no solvente de extração. As analises de aminoacidos revelaram que albuminas e globulinas (F1) do endosperma do Adlay são ricas Acido glutamico, Acido aspartico, glicina e alanina. As prolaminas (F2) são ricas em Acido glutamico, alanina, leucina prolina. As prolaminas não são completamente extraidas, mesmo quando 20% de 2-ME e utilizado no solvente de extração, e permanecem como uma contaminação das proteinas residuais (F3), o que faz com que a composição de aminoacidos da F3 seja similar A da F2. Analise das frações proteicas do Adlay atraves de eletroforese em SDS-PAGE demonstrou que a F1 e F3 possuem um padrão bastante complexo de bandas, enquanto que a F2 se subdividiu em apenas cinco bandas de pesos moleculares distintos. Estas cinco bandas foram denominadas de C1, C2, C3, C4 e C5. Anticorpos policlonais foram produzidos contra as bandas de coixina C2 e C3. Os anticorpos contra C2 reagiram com a banda C2 e apresentaram reação cruzada com proteinas de peso molecular mais elevado que o das coixinas e que so foram extraidas quando 20% de 2-ME foram utilizados no solvente de extração. Anticorpos contra C3 reconheceram a banda C3 e apresentaram reação cruzada com uma proteina de 40.5 kDa extraida quando 2-ME era utilizado no solvente de extração.Da analise das coixinas em focalização isoeletrica (IEF) revelou a presença de sete bandas principais. Quando as bandas individuais de IEF foram submetidas a SDS-PAGE, subdividiram-se em mais de uma classe de peso molecular distinto. As bandas de pI 7,26, 6.91, 6,55, 6,34 e 6,20 apresentaram reaçãoo com ambos os antisoros. As proteinas do endosperma do Adlay foram comparadas com as do Zea mays L. var. Maya. Foi constatado que o Maya possui um total de 8,7% de proteina no endosperma, sendo que 51,7% desta proteina são representados por prolaminas que, no caso do milho, são denominadas de zeina. A analise de aminoacidos da Fl, F2 e F3 do Maya revelou que existe uma similaridade na composição de aminoacidos das frações proteicas do Maya e do Adlay. Quando submetidas a SDS-PAGE, a F1 e F3 do Maya apresentaram um complexo padrão de bandas, sendo que algumas das bandas tinham o mesmo peso molecular de bandas encontradas nos padrões de Fl e F3 do Adlay. A F2 do Maya, do mesmo modo que a F2 do Adlay, apresentou uma baixa heterogeneidade em SDS-PAGE. As sete bandas encontradas no padrão de SDS-PAGE do Maya foram denominadas de Z1, Z2, Z3, Z4, Z5, Z6 e Z7. As prolaminas do Maya não apresentaram reação cruzada com o antisoro contra a classe de coixina C2. Contudo, o antisoro contra C3 apresentou reação cruzada com Z1 e com proteInas de 40,5 e 50 kDa extraIdas na presenCa de 2-ME. Em IEF, a zeina do Maya apresentou oito bandas principais que, quando foram submetidas a SDS-PAGE, revelaram ser principalmente do tipo Z2 e/ou Z3. Apesar da dificil visualização no gel de SDS-PAGE, bandas do tipo Z1 se encontram nos mesmos pis das bandas Z2 e Z3, como foi detectado atraves de analise imunologica com o antisoro contra C3. Os DNAs genomicos do Adlay e do Maya foram digeridos com as enzimas de restrição Eco RI, Bam HI e Hind III e submetidos a hibridizações com as sondas de cDNA da zeina pZ 22,3 e pZ 19,1. Enquanto que o DNA do Maya apresentou homologia com ambas as sondas de zeina, o DNA do Adlay so apresentou homologia com a sonda pZ 22,3. As proteinas do endosperma do Coix lacryma-jobi var. Acre, da linhagem de milho L1038 e dos teosintes Zea mays mexicana e Zea luxurians foram comparadas com as do Adlay e do Maya. Ficou constatado que os padrões de SDS-PAGE da Fl, F2 e F3 do Adlay e do Acre são praticamente iguais. Os padrões de SDS-PAGE da Fl, F2 e F3 dos milhos e teosintes tambem são praticamente iguais. Quando submetida a reações imunologicas, a F2 do Acre apresentou reação cruzada com os antisoros contra as classes de coixina C2 e C3 do Adlay. Da mesma forma que havia sido observado para F2 do Maya, as F2 da L1038, Zea mays mexicana e Zea luxurians nAo apresentaram reação cruzada com o antisoro contra a classe de coixina C2 do Adlay, mas apresentaram reação cruzada com o antisoro contra C3. Da homogeneidade encontrada nos padrões de SDS-PAGE da F2 do Adlay e do Acre e da F2 do Maya, L1038, Zea mays mexicana e Zea luxurians fez com que estas proteinas fossem submetidas a focalização isoeletrica e, subsequentemente, comparadas com os padrões de IEF de prolaminas de outras linhagens de milho e variedades de Coix e teosinte, onde se observou um padrão individual de bandas para cada um dos materiais analisados. Os DNAs genomicos do Zea mays mexicana, Zea luxurians, L1038 foram digeridos com as enzimas de restrição Eco RI e Bam HI e submetidos a hibridizações com as sondas pZ 22,3 e pZ 19,1. Foi constatado que existe homologia entre os DNAs dos milhos e teosintes e ambas as sondas de cDNA da zeina / Abstract: The seed proteins of Coix lacryma-jobi L. var. Adlay were extracted and characterized. The endosperm of Adlay contains ca. 21% of proteins. The major protein fraction of the endosperm of Adlay is a prolamin, known as coixin. The amount of coixin extracted ranges from 10.8% to 77.8%, depending upon the concentration of 2-mercaptoethanol in the extraction solvent. Amino acid analysis revealed that albumins and globulins (F1) from Adlay endosperm are rich in glutamic acid, aspartic acid, glycine and alanine. The prolamine (F2) are rich in glutamic acid, alanine, leucine, and proline. The prolamins are not completely extracted, even when 20% of the 2-ME is used in the extraction solvent. They remain as a contamination of residual proteins(F3). Because of the incomplete extraction of coixin, the amino acid content of F3 proteins is similar to that of F2. SDS-PAGE analysis of Adlay protein fractions showed that F1 and F3 have a complex pattern of bands, while F2 has only five bands. Those five bands were denominated C1, C2, C3, C4, and C5. Polyclonal antibodies were raised against the C2 and C3 protein bands. The C2 antibodies recognized the C2 band and cross-reacted with proteins of higher molecular weight that were extracted only when 20% of 2-ME were used in the extraction solvent. The C3 antibodies recognized the C3 band and cross-reacted with a 40.5 kDa protein, extracted when 2-ME was included in the extraction solvent. Isoelectric focusing (IEF) analysis of coixin revealed the presence of seven major bands. When individual IEF bands were submitted to SDS-PAGE, they subdivided into more than one molecular weight class. The IEF bands with pI 7.26, 6.91, 6.55, 6.34, and 6.20 reacted with both antibodies. The endosperm proteins of Adlay were compared with those of Zea mays L. var. Maya. It was observed that Maya has 8.7% of protein in the endosperm. Aproximately 51.7% of that protein are prolamins, which are called zein in corn. Amino acid analysis of Maya F1, F2, and F3 showed that there is a similarity between the amino acid composition of the protein fractions of Maya and Adlay.When submitted to SDS-PAGE, the F1 and F3 of Maya gave a complex band pattern. Some of the bands observed the F1 and F3 of Maya had the same molecular weight of bands found in the F1 and F3 of Adlay. Like the F2 of Adlay, the F2 of Maya showed low heterogeneity in SDS-PAGE. The seven bands observed in Maya F2 SDS-PAGE pattern were named Z1, Z2, Z3, Z4, Z5, Z6, and Z7. No cross-reaction was observed between the prolamins of Maya and C2 antibody. However, a cross-reaction was observed between C3 antibody and Z1. Proteins extracted in the presence of 2-ME with 40.5 and 50 kDa a1so cross-reacted with C3 antibodies. A total of eight major bands were observed for Maya in IEF. When submitted to SDS-PAGE, those bands revealed to be mostly Z2 and Z3. Bands Z1 were detected in SDS-PAGE with C3 antibody in the same pI of Z2 and Z3 bands.The genomic DNAs of Adlay and Maya were digested with the restriction enzymes Eco RI, Bam HI, and Hind III and submitted to hybridizations with zein cDNA probes pZ 22.3 and pZ 19.1. While the DNA of Maya showed homology with both probes, the DNA of Adlay showed homology only with pZ 22.3. The endosperm proteins of Coix lacryma-jobi var. Acre, corn inbred 1ine 1038, and of the teosintes Zea mays mexicana and Zea luxurians were compared with the ones of Adlay and Maya. It was observed that the SDS-PAGE patterns of the F1, F2, and F3 of Adlay and Acre were practically the same. The SDS-PAGE patterns of the F1, F2, and F3 of the corn and teosintes were also practically the same. When submitted to immunological reactions, a cross-reaction was observed between Acre F2 and C2 and C3 antibodies. As it was found for Maya F2, no cross-reaction was observed for L1038, Zea mays mexicana, and Zea luxurians F2 and C2 antibody. However, a cross-reaction was observed for the F2 of those materials and C3 antibody. The lack of heterogeneity observed for the SDS-PAGE pattern of the F2 of Adlay and Acre and the F2 of Maya, L1038, Zea mays mexicana, and Zea luxurians was the reason why those proteins were submitted to isoelectric focusing and after that were compared with the IEF pattern of the prolamins of other corn inbred lines and Coix and teosinte varieties. Those comparisons showed an individual pattern for each material analysed. The genomic DNA of Zea mays mexicana, Zea luxurians, L1038, and Maya were digested with the restriction enzymes Eco RI and Bam HI and submitted to hibridization with pZ 22.3 and pZ 19.1. It was observed that there is a homology between the DNAs of corn and teosinte and both probes / Doutorado / Doutor em Ciências

Orientador : Norma Mancilla Diaz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-07-15T16:54:17Z (GMT). No. of bitstreams: 1 RamirezAscheri_JoseLuis_M.pdf: 3328496 bytes, checksum: bf60b216c5a8ce33d58e0dd60c719ed8 (MD5) Previous issue date: 1987 / Resumo: O presente trabalho objetivou o estudo das condições de extração de amido do cereal Adlay (Coix lacryma jobi L.), assim como a caracterização físico química desta provável fonte de amido. A composição química do grão de Adlay apresentou, assim como outros cereais, um alto teor de carboidratos (69,51%), porém também ura teor relativamente alto de proteínas (16,82%). Os estudos de beneficiamento e moagem da semente mostraram que é possível produzir farinhas utilizando a beneficiadora de arroz e posterior moagem no moinho Brabender Quadrumat Senior. O amido de Adlay obtido a partir de farinhas, usando tolueno:água na proporção de 1:8 apresentou rendimentos de aproximadamente 44 ,9% e teores de proteína e lipídios de aproximadamente 0,5% e 0,89%, respectivamente. O teor de amido danificado foi de 1,2 Unidades Farrand. O exame microscópico do amido de Adlay em microscópio óptico mostrou que este grânuIo é pequeno (1,2 a 3,5 micra) e tem forma esférica e achatada com depressão central. Com luz polarizada os grânulos apresentaram cruz de malta central. A perda da foi birrefringência inicia-se aproximadamente a 68º C é esta perda e praticamente total a 75ºC. A densidade absoluta foi 1,4793 g/ml e a viscosidade intrínseca 1,3257 dl/g. A capacidade de absorção em água fria foi de 119,2% e o índice de solubilização 0,09%. O Poder de Inchamento e índice de solubilização a 95ºC foi de 48,35 g/g e 20,81 % respectivamente. A reação com lodo apresentou cor marrom escura, semelhante a encontrada no amido de milho ceroso, porém diferente da cor azul apresentada pelo amido de milho normal. O valor de "Blue Value" foi de 2,32% de amilose, o que justifica a cor da reação com iodo e o fato de não ter conseguido precipitação da amilose no fracionamento do amido. Na determinação da cristalinidade por raios-X os difractogramas obtidos apresentaram o padrão do tipo A, típico de amido de cereais. O estudo das propriedades de pasta do amido de Adlay mostrou que este tipo de amido apresenta alta temperatura de inicio de formação de pasta comparado com amidos normais de cereais, porém a faixa de gelatinização é estreita, mostrando que as forças que mantém a estrutura do grânulo são homogêneas. Uma vez atingida a viscosidade máxima, esta diminue rápidamente, aproximadamente até 50% da viscosidade máxima. Durante o ciclo de resfriamento o aumento de viscosidade é pequeno de aproximadamente 10% da viscosidade mínima a temperatura constante de 95ºC. Os testes de retrogradação mostraram que o amido não apresentou exsudação de água após 15 dias de armazenamento a - 2ºC . Os valores de transmitância óptica a 95ºC e/ou com posterior resfriamento foram mais altos que o do milho normal. Amidos tratados a diferentes pHs (3-8) não mostraram mudanças significativas nas suas propriedades de pasta, assim como também a adição de sacarose (10-60%) , glicose (2-30%) e cloreto de sódio (2-6%). / Abstract: The objective of this research was to study the conditions for starch extraction from the cereal Adlay (Coix lacryma joblL.) as well as to carry out physico-chemical characterization of this probable starch source. Like other cereals, the Adlay grain showed high levels of carbohydrate (69.51%) but accompanied by relatively high levels of protein (16.82%). Processing and milling studies of the grain showed that it was possible to produce flour using a rice processor and subsequent Killing in the Brabender Quadrumat Senior mill. Using toluene: water mixture in the proportion 1:8, starch yields of approximately 44.9% were obtained from Adlay flour with protein and lipid levels of approximately 0.5% and 0.89% respectively. The level of damaged starch was 1.2 Farrand units. Under the optical microscope, the Adlay starch grain was shown to be small (1.2-3.5 u), spherical and, flattened, with a central depression. Under polarized light, the granules presented a central malta cross. The loss of birefringence started at approximately 68ºC, being practically complete at 75ºC. The absolute density was 1,4793 g/ml and the Intrinsic viscosity 1.3257 dl/g. The absorption capacity in cold water was 119.2% and the solubility index 0.09%. The swelling power and solubility index at 95ºC were 48.35 g/g and 20.81% respectively. A dark brown colour was produced with iodine similar to that obtained with waxy corn starch, but different from the blue colour obtained with the starch from normal corn. The Blue Value indicated a 2,32% content of amylose,, which justifies the colour obtained in the lodine reaction and the fact that there was no precipitation of amilse during the fractionation of the starch. The diffractograms obtained in the determination of cristallinity by X-rays were of the type A pattern, typical of cereal starches. In a study of the properties of Adlay starch paste, it was shown that the temperature for the inicial paste formation was high as compared to other cereal starches , but that the gelatinization range was narrow, showing that the forces maintaining the structure of the grain were homogeneous. Once maximum viscosity was attained there was a rapid loss, up to 50% of the maximum viscosity. The viscosity increase during the cooling cycle was small, amounting to aproximately 10% of the minimum viscosity at the constant temperature of 95ºC. Retrogradation tests showed no exudation of water from the starch after 15 days of storage at -2ºC. The optical transmittance values at 95ºC and/as with subsequent coolling, were higher than those obtained with normal corn starch, treatment of the starch at different pH values (3-8) showed no significant changes In the properties of the starch paste and nor did the addittions of sucrose (10-60%) , glucose (2-30) or sodium chloride (2-6%). / Mestrado / Mestre em Tecnologia de Alimentos

Orientador : William Jose da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-14T04:10:06Z (GMT). No. of bitstreams: 1 Mello_LucianeVieirade_M.pdf: 6763272 bytes, checksum: b58f3f7363ed5bebacdeed0ac054c1fa (MD5) Previous issue date: 1989 / Resumo: O presente trabalho teve como objetivo principal gerar conhecimentos sobre a estrutura genética de algumas populações de Coix, em função de seu sistema reprodutivo. Para tanto, efetuou-se uma análise comparativa de várias populações, e realizou-se estudos de aspectos de biologia de reprodução, canalizando-os para a estimativa da taxa de cruzamento dessas populações.Os resultados mostraram que a população Adlay possue características de uma populção domesticada. A população Rosadlay apresentou potencial para produção de grãos e grande massa verde,devendo. portanto ser avaliada como forrageira. ... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The main objective of this work was to generate knowledge about the genetic structureof some Coix populations,based upon their reproductive system. Thus, a comparative reproductive analysis of many populations was carried out, and studies on the biology of reproduction were made, aiming to estimate the crossing rates of such populations.The results suggested that the Adlay population has withholds characteristics of a domesticated population. As the Rosadlay population showed a potentiality for grain yield and green mass, it should therefore be evaluated as a forage crop. ... Note: The complete abstract is available with the full electronic digital thesis or dissertations / Mestrado / Genetica / Mestre em Ciências Biológicas

Orientador : Ricardo Antunes de Azevedo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-28T20:45:31Z (GMT). No. of bitstreams: 1 Lugli_Juverlande_D.pdf: 4954766 bytes, checksum: b3132d4ab3c7474e41b4c3a950bffe9a (MD5) Previous issue date: 2001 / Doutorado

Orientador: Adilson Leite / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-29T00:48:15Z (GMT). No. of bitstreams: 1 Siloto_RodrigoMarinsPeixoto_M.pdf: 7557384 bytes, checksum: f29ddd8d03f039df7469cc5db17d8976 (MD5) Previous issue date: 2001 / Mestrado / Genetica Vegetal e Melhoramento / Mestre em Genética e Biologia Molecular

Orientador: Adilson Leite / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-24T10:37:31Z (GMT). No. of bitstreams: 1 Oliveira_AndreLuizVettorede_D.pdf: 9002874 bytes, checksum: 1027adb35ed60662c9c5e7fa959bc387 (MD5) Previous issue date: 1998 / Doutorado / Genetica / Doutor em Ciências Biológicas

Orientador: Adilson Leite / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-21T18:57:19Z (GMT). No. of bitstreams: 1 Silva_FelipeRodriguesda_M.pdf: 5917305 bytes, checksum: f5a2ce6dd1986e5219fe86f31267cb3c (MD5) Previous issue date: 1996 / Resumo: As prolaminas, proteínas de reserva das sementes de cereais, são codificadas por uma série de genes regulados coordenativamente de forma específica ao nível de tecido e estágio de desenvolvimento. Estas proteínas são agrupadas em classes em função das similaridades na estrutura primária e conseqüente solubilidade. A expressão dos genes que as codificam é regulada principalmente ao nível da transcrição. As prolaminas de Coix são chamadas coixinas e representam mais de 70% do conteúdo protéico do endosperma. De acordo com sua solubilidade diferencial, as coixinas são classificadas em a e y-coixinas. Os dados moleculares obtidos até o momento indicam um alto grau de similaridade entre os genes que codificam as prolaminas de milho, Coix e sorgo. A expressão coordenada das prolaminas se dá através de mecanismos comuns a todas as classes. Entretanto, estudos recentes sobre a mutação opaco-2 mostram claramente que as a- e y prolaminas são reguladas também por um mecanismo exclusivo para estas classes. Tal fato sugere o envolvimento vários mecanismos regulando a transcrição dos genes de prolaminas. Devido principalmente à mutação opaco-2, os mecanismos envolvidos na regulação gênica das a-prolaminas são bem estudados. Pouco é conhecido sobre estes mecanismos nas y-prolaminas. Entretanto, enquanto as y-prolaminas são codificadas por, no máximo, dois genes, as «-prolaminas são codificadas por uma família muJtigênica. Tal fato torna as y-prolaminas modelos interessantes no melhoramento molecular de cereais. Nesta tese o gene da y-coixina (AGCX23.1) foi isolado de uma biblioteca genômica construída no fagemídeo Â-dash, utilizando-se um clone de cDNA de y-coixina como sonda. A seqüência da região promotora do gene foi alinhada com as seqüências dos promotores das y-prolaminas de milho e sorgo, revelando uma série de elementos conservados. Alguns destes e_mentos são semelhantes a elementos cis já descritos, como o prolamín box e os sítios de ligação dos fatores GCN4 de leveduras e C/EBP de animais. Experimentos de expressão transitória comprovaram que o promotor do gene da y-coixina é capaz de dirigir a expressão do gene da _-glicoronidase em endosperma imaturo de milho. A análise de deleção do promotor sugere que diversos elementos podem estar envolvidos na regulação de sua expressão. Experimentos de retardamento em gel provaram que três segmentos distintos do promotor da y-coixina ligam-se a fatores nucleares de maneira específica / Abstract: Prolamins, the major cereal storage proteins, are encoded by genes coordinately regulated in a tissue- and developmental stage-specific manner during seed development. There are several prolamin genes encoding proteins of discrete molecular sizes, which are divided in classes according to similarities in their primary structures and solubility. The expression of these genes is regulated primarily at the transcriptional level. The Coix prolamins, known as coixins, represent more than 70% of the total endosperm protein. Coixins can be separated in two fractions based on their differential solubility: (X- and y-coixins. The overall molecular data shows a high degree of similarity among the genes encoding the prolamins of maize, Coix and Sorghum. The coordinated expression of the prolamin genes is accomplished by a common regulatory mechanism. Still, recent studies on the opaque-2 mutation clearly demonstrated a distinct transcriptional regulation at the class level for the a- and p-prolamins. Therefore, multiple complex regulatory mechanisms are conceivably involved in the regulation of prolamin genes. Although the mechanisms of gene regulation for the a-prolamins are well studied, mostly because of the opaque-2 mutant of maize, little is known about the mechanisms controlling the y-prolamin genes. Also, while the a-prolamins are encoded by multigene families, the y-prolamíns are encoded by one or two genes, which heightens the importance of the y-prolamíns in molecular improving of cereais. In this work the y-coixin gene (I"GCX23.1) was isolated from a Coix genomic À-dash library. The library was screened using a y-coixin cDNA clone as probe. In order to elucidate the transcriptional regulation of the y-prolamin genes, the y-coixin promoter sequence was aligned with the promoter. sequences of the maize and sorghum y-prolamins genes. Several conserved motifs were found in the upstream region of these genes. Some of these motifs resembles cis-acting elements. such as the cereal prolamin box and the binding sites for yeast GCN4 and animal C/EBP transcriptional factors. Transient expression assays demonstrated the ability of the y-coixin promoter to drive the expression of the ß-glucuronidase reporter gene in immature maize endosperm. Deletion analysis of the promoter sequence suggested that several elements might be involved in its regulation. At least three distinct segments of the y-coixin promoter bind specifically to nuclear factors, as demonstrated by means of gel retardation assay / Mestrado / Genetica de Plantas / Mestre em Ciências

A portable infra red gas analyzer was used to investigate the interactive effects of light, temperature, and CO,jO, ratios under controlled environmental conditions in an attempt to model gas exchange characteristics of Coix Iachryma-jobi L. Plotting light response curves as a function of temperature (20, 25 30 and 35°C) revealed no sign of light saturation even at a photosynthetic photon flux density (PPFD) close to 2000 !Lmol m-' sol. High net assimilation rates (A) of approximately 24 !Lmol CO, m"s'! were realized at 30-35°C. Assimilation (A) versus internal CO, partial pressure (C,) curves showed a steep rise with increase in C, but saturated at approximately 150 (JLII-!) and all the results, either in the absence or presence of 0" showed a similar response under all temperature regimes. C. Iachryma-jobi exhibited low CO, compensation points cr ) between 0 and 10 JLlI-! under similar experimental temperatures and either at 0 or 21%0,. The slopes of double reciprocal plots of llA versus llCi, were nearly identical and crossed the yintercept at almost identical points under all 0, concentrations. These data indicate first; that there was no apparent 0, inhibition and second; indicated that the apparent inhIbitor constant (K,) for 0, at the site of carboxylation did not change with increase in [OJ from 0 to 21% oxygen. These observations were further confirmed by results obtained from the analysis of apparent carboxylation efficiency (CE, as defined as the slope of response of A to increasing CO,), as no inhibition of A with increase of [OJ occurred. These characteristics were consistent with typical features of C,photosynthesis. The absence of 0, inhibition and low r values indicated that an efficient CO, concentrating mechanism which eliminates photorespiration exists in C. Iachryma-jobi. At the light microscope level, leaf anatomy exhibited typical C, structure viz. bundle sheath with large chloroplasts and this sheath is further surrounded by a radiate Kranz mesophyU cells. Furthermore the anatomical features suggested that C. wchryma-jobi was an NADP-ME species. Stomatal conductance (g,) to assimilation (g,/A) indicated an increase in A with decrease in g" an essential feature of improving water use efficiency (WUE), but one which drastically reduces CO, diffusion rate. The physical lintitation (stomatal lintitation, t) to CO, diffusion under various [0,] and temperatures, but constant PPFD, did not exhibit statistically significant change in t values at either 0 or 21% a, within each temperature regime, however there was a marked decrease in t as the plant approached its optimum photosynthetic temperature.