When Less Is More: Sex Ratios for the Mass-Rearing of Anastrepha ludens (Diptera: Tephritidae).

Anastrepha ludens (Loew) is one of the most important pests of citrus and mango crops in Mexico. A method used to control this pest is the sterile insect technique, which consists in the mass production, irradiation, and release of insects in affected areas. The production of insects begins with the establishment of colonies to produce eggs, which must be highly fertile to ensure an adequate production of larvae. However, female fecundity and fertility can be affected by adult density and sex ratio, thus an optimal sex ratio in mass-rearing cages must be used. The genetic sexing strain of A. ludens (Tapachula-7) allows the identification of the sex at the pupal stage, making it possible to establish rearing cages with different sex ratios. We determined if different sex ratios have an effect on egg production. Two sex ratios (4♀: 1♂ and 1♀: 1♂) were compared. Fecundity, fertility and survival at different ages were also determined. Higher fertility and fecundity per female were observed at a ratio of 4:1. However, females with higher fecundity had reduced survival probabilities. In conclusion, maintaining colonies with a lower proportion of males in cages ensures a greater fecundity and fertility. Further research is necessary to understand whether results can be attributed to lower male harassment in cages.

Formation of nanotubular TiO2 structures with varied surface characteristics for biomaterial applications.

Nanotubular structures were generated on the surface of titanium c.p. by anodization technique in an aqueous solution of acetic acid (14% v/v) with different sources of fluoride ion (HF, NaF, NH4 F). The aim of using these three different compounds is to study the effect of the counterion (H+ , Na+ and NH4+) on the morphology, wettability and surface free energy of the modified surface. Nanotubes were generated at 10 and 15 V for each anodizing solution. To further improve surface characteristics, the samples were heat-treated at 600°C for 4 h and at 560°C for 3 h. SEM images revealed the formation of nanotubes in all anodizing conditions, while their diameter increased proportionally to the electric potential. X-ray diffraction and micro-Raman spectroscopy results showed the presence of both anatase and rutile phases, with a higher content of rutile in the coatings obtained using NH4 F and an applied potential of 10 V. The heat-treatment significantly increased the wettability of the anodic coatings, especially for the coating obtained at 15 V with HF, which showed values < 7 degrees of contact angle. Besides, the nanotubes show a decrease in diameter due to the heat treatment, except for the nanotubes formed in NH4 F. Depending on their surface properties (e.g. low contact angle and high surface free energy), these coatings potentially have great potential in biomedical applications, sensors devices, and catalytic applications among others. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1341-1354, 2018.

[Relation between preoperative prognostic Onodera's Index and postsurgery complications in the R0 gastric carcinoma resection]. / Relación entre el índice de Onodera pre-operatorio y las complicaciones post-cirugía R0 en el cáncer de estómago.

BACKGROUND: It has been postulated in the Asian literature that a low prognostic nutritional index (OI) could be associated with a higher rate of complications following radical gastric cancer surgery, but there is a lack of data concerning western countries. The aim is to analyze the relationship between a low preoperative OI and the frequency and severity of surgical complications in R0 gastric cancer resection. PATIENTS AND METHODS: In the present article, 124 cases of gastric cancer with R0 resection were reviewed. An OI <45 was considered pathologically low. The complication rate was compared between both groups: OI <45 vs OI =45. A multivariate analysis was performed adjusting for: age > 68 years, ASA score, preoperative hemoglobin level <12 g/dL, pTNM stage, administration of neoadyuvant therapy and type of gastrectomy. The relationship between a PNI<45 and the severity of complications graded according to the Clavien-Dindo classification was determined. RESULTS: We registered mild complications in 11.3% of cases, severe complications in 9.7% and a mortality rate of 2.4%. Patients with a OI <45 showed a higher complication rate: 37.7% versus 12.7% [odds ratio (OR) = 4.17; CI95% = (1.71 - 10.20 p = 0.001)], confirmed by multivariate analysis: [OR = 4.17; CI95% = (1.54 - 11.30); p = 0.005]. Patients with OI <45 had more severe complication-exitus: 20.8% versus 5.6% [OR = 4.39; CI95% = (1.31 - 14.68); p = 0.011]. CONCLUSIONS: We confirmed that patients with a low preoperative OI show a higher independent risk of complications after a R0 gastric cancer resection in a western country as well. Complications, in these cases with OI <45, registered a significantly higher severity grade.

Relación entre el índice de Onodera pre-operatorio y las complicaciones post-cirugía R0 en el cáncer de estómago / Relation between preoperative prognostic Onodera’s Index and postsurgery complications in the R0 gastric carcinoma resection

Fundamento: En publicaciones asiáticas se postula que un Índice de Onodera (IO) bajo puede asociarse con una mayor frecuencia de complicaciones post-resección radical del cáncer gástrico, careciendo de resultados en áreas occidentales. En el presente trabajo se analiza la relación entre un IO pre-operatorio bajo con la frecuencia y la gravedad de las complicaciones post-cirugía R0 en el cáncer gástrico. Pacientes y métodos: Se revisaron 124 tumores gástricos con resección R0. Considerando patológicamente bajo un IO <45, estudiamos la frecuencia de complicaciones entre los grupos con IO menor y ≥45. En el análisis multivariante incluimos como variables de ajuste la edad mayor de 68 años, puntuación ASA, hemoglobina pre-operatoria menor de 12 g/dL, estadio pTNM, infiltración serosa, invasión ganglionar y tipo de gastrectomía realizada. Determinamos la relación entre IO <45 y la frecuencia y gravedad de las complicaciones, según la clasificación de Clavien-Dindo modificada. Resultados: Se registraron complicaciones leves en un 11,3%; graves 9,7% y exitus 2,4%. Los pacientes con IO <45 presentaron mayor frecuencia de complicaciones: 37,7% versus 12,7% [ odds ratio (OR) = 4,17; IC 95% = (1,71-10,20); p = 0,001], confirmada en el análisis multivariante: [OR = 4,17; IC 95% = (1,54-11,30); p = 0,005]. Los pacientes con IO <45 tuvieron más complicaciones graves-exitus: 20,8% versus 5,6% [OR = 4,39; IC 95% = (1,31-14,68); p = 0,011]. Conclusiones: También en un país occidental, los pacientes con IO pre-operatorio bajo (<45) muestran un mayor riesgo independiente de presentar complicaciones tras la resección R0 del carcinoma gástrico. Adicionalmente, las complicaciones registradas en los casos con IO <45, muestran una significativa mayor gravedad (AU)

Background: It has been postulated in the Asian literature that a low prognostic nutritional index (OI) could be associated with a higher rate of complications following radical gastric cancer surgery, but there is a lack of data concerning western countries. The aim is to analyze the relationship between a low preoperative OI and the frequency and severity of surgical complications in R0 gastric cancer resection. Patients and methods: In the present article, 124 cases of gastric cancer with R0 resection were reviewed. An OI <45 was considered pathologically low. The complication rate was compared between both groups: OI <45 vs OI ≥45. A multivariate analysis was performed adjusting for: age > 68 years, ASA score, preoperative hemoglobin level <12 g/dL, pTNM stage, administration of neoadyuvant therapy and type of gastrectomy. The relationship between a PNI<45 and the severity of complications graded according to the Clavien-Dindo classification was determined. Results: We registered mild complications in 11.3% of cases, severe complications in 9.7% and a mortality rate of 2.4%. Patients with a OI <45 showed a higher complication rate: 37.7% versus 12.7% [odds ratio (OR) = 4.17; CI95% = (1.71 - 10.20 p = 0.001)], confirmed by multivariate analysis: [OR = 4.17; CI95% = (1.54 - 11.30); p = 0.005]. Patients with OI <45 had more severe complication-exitus: 20.8% versus 5.6% [OR = 4.39; CI95% = (1.31 - 14.68); p = 0.011]. Conclusions: We confirmed that patients with a low preoperative OI show a higher independent risk of complications after a R0 gastric cancer resection in a western country as well. Complications, in these cases with OI <45, registered a significantly higher severity grade (AU)

Development and validation of a computerized algorithm for International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI).

STUDY DESIGN: Validation study. OBJECTIVES: To describe the development and validation of a computerized application of the international standards for neurological classification of spinal cord injury (ISNCSCI). SETTING: Data from acute and rehabilitation care. METHODS: The Rick Hansen Institute-ISNCSCI Algorithm (RHI-ISNCSCI Algorithm) was developed based on the 2011 version of the ISNCSCI and the 2013 version of the worksheet. International experts developed the design and logic with a focus on usability and features to standardize the correct classification of challenging cases. A five-phased process was used to develop and validate the algorithm. Discrepancies between the clinician-derived and algorithm-calculated results were reconciled. RESULTS: Phase one of the validation used 48 cases to develop the logic. Phase three used these and 15 additional cases for further logic development to classify cases with 'Not testable' values. For logic testing in phases two and four, 351 and 1998 cases from the Rick Hansen SCI Registry (RHSCIR), respectively, were used. Of 23 and 286 discrepant cases identified in phases two and four, 2 and 6 cases resulted in changes to the algorithm. Cross-validation of the algorithm in phase five using 108 new RHSCIR cases did not identify the need for any further changes, as all discrepancies were due to clinician errors. The web-based application and the algorithm code are freely available at www.isncscialgorithm.com. CONCLUSION: The RHI-ISNCSCI Algorithm provides a standardized method to accurately derive the level and severity of SCI from the raw data of the ISNCSCI examination. The web interface assists in maximizing usability while minimizing the impact of human error in classifying SCI. SPONSORSHIP: This study is sponsored by the Rick Hansen Institute and supported by funding from Health Canada and Western Economic Diversification Canada.

Frecuencia de insuficiencia de Vitamina D en adultos jóvenes sanos de Asunción / Frequency of Vitamin D insufficiency in healthy young adults of Asunción

La insuficiencia de vitamina D sérica se asocia a diversos trastornos, con alta prevalencia a nivel regional y mundial. En nuestro país no existen estudios publicados al respecto. En este estudio observacional, descriptivo, con componente analítico se determinaron niveles de vitamina D y prevalencia de su insuficiencia en jóvenes y se indagó posibles asociaciones con factores de riesgo conocidos como la falta de exposición solar, uso de protectores solares, y falta de consumo de alimentos ricos en vitamina D. Fueron incluidos 100 estudiantes y funcionarios del Hospital de Clínicas de la Universidad Nacional de Asunción, a quienes se les tomó una muestra de sangre y llenaron un cuestionario. Los niveles de vitamina D fueron determinados por el método ECLIA (inmunoensayo de electro quimioluminiscencia). Las edades estaban entre 20 y 30 años, el 69% era del sexo femenino. La concentración media ± desvío estándar de vitamina D fue de 17,6 ± 6,25 ng/dl (rango: 4-38). El 53% de los participantes presentaba insuficiencia (10 a 20 ng/dL) y 11% deficiencia (<10 ng/dL) de vitamina D. Aunque los participantes que reportaron consumir lácteos y no utilizar protectores solares tuvieron mayores niveles de vitamina D, la diferencia no fue estadísticamente significativa. Se encontró una frecuencia elevada de insuficiencia de vitamina D en esta población, en concordancia con los hallazgos de estudios similares a nivel mundial y regional. Se recomienda la suplementación con vitamina D en la población de manera a prevenir los trastornos asociados con la deficiencia de esta vitamina.

Insufficientserum vitamin D is associated with various disorderswith highprevalence at global and regional levels. In our country,there are notpublishedstudiesrelated to this matter.Inthisdescriptive,observational studywithanalytical component,thelevels ofvitamin Dand the prevalence of its insufficiencywere determined in young peopleand also thepossible associations with knownriskfactors likesun exposure, sunscreen useand lack ofconsumption ofvitamin D-enrichedfoodswere analyzed.One hundred medical students andmembers of thestaff of theHospital de Clinicas ofthe National University of Asuncion, Paraguaywere included.Participants wereaged 20to30 yearsand69%of them werewomen.The mean concentrationof vitamin Dwas 17.6 ± 6.25 ng/dl (range: 4-38);53% oftheparticipants had insufficientlevelsof vitamin D(10-20 ng/dL) and 11%had vitamin Ddeficiency (less than 10 ng/dL).Althoughtheindividuals whoreportedconsumption of dairyproductsand non-use of sunscreenhad higher levels ofvitamin D,thedifferencewas not statistically significant. A high frequency ofvitamin D insufficiency was foundin this population in agreementwith similarstudiescarried outatworldwideandregionallevels.Vitamin D supplementationisrecommendedin thepopulation to prevent disorders associated withthedeficiency.

ATP-induced sucrose efflux from red-beet tonoplast vesicles.

Sucrose efflux from the vacuole of mobilizing red-beet (Beta vulgaris L.) hypocotyl cells was investigated using purified tonoplast vesicles. Tonoplast vesicle purity was assured by the immunoreactivity to antibodies raised against the vacuolar ATPase and by the strong inhibition exhibited by the H+-ATPase to bafilomycin-A and NO3-. Inhibition of the H+-ATPase by vanadate and azide was negligible. Sucrose was loaded into tonoplast vesicles by using the pH-jump method of energization. Addition of ATP to sucrose-loaded vesicles in the presence of bafilomycin-A resulted in efflux of a significant amount of sucrose. During ATP-induced sucrose efflux, bafilomycin-insensitive ATPase activity increased significantly with no increase in H+-translocating activity. The additional bafilomycin-A insensitive ATPase activity observed in sucrose-loaded vesicles was completely inhibited by vanadate as was the efflux of sucrose. Similar to vanadate, thapsigargin was also inhibitory to sucrose efflux and to the bafilomycin-A insensitive ATPase activity. The data indicate that vacuolar sucrose can be actively mobilized by a specific ATP-dependent efflux mechanism.

Citrate uptake into tonoplast vesicles from acid lime (Citrus aurantifolia) juice cells.

Citrate transport into the vacuoles of acid lime juice cells was investigated using isolated tonoplast vesicles. ATP stimulated citrate uptake in the presence or in the absence of a Delta mu H+. Energization of the vesicles only by an artificial K+ gradient (establishing an inside-positive Delta psi) also resulted in citrate uptake as was the case of a Delta pH dominated Delta mu H+. Addition of inhibitors to endomembrane ATPases showed no direct correlation between the inhibition to the tonoplast bound H+/ATPase and citrate uptake. The data indicated that, although some citrate uptake can be accounted for by Delta psi and by a direct primary active transport mechanism involving ATP, under in vivo conditions of vacuolar pH of 2.0, citrate uptake is driven by Delta pH.

Fru 2,6-P2 and citrate: intracellular distribution in citrus tissues and effect on grapefruit leaf PFP.

Grapefruit leaf PFP was studied for its activation by fructose 2,6-bisphosphate (Fru 2,6-P2) in the forward and reverse reactions. In the glycolytic reaction, a Ka of 4.0 +/- 0.12 nM was obtained. This constant is affected by the presence of increasing concentrations of citrate (1, 5 and 20 nM) with a Ka(citrate) of 4.5 +/- 0.09, 6.9 +/- 0.05 and 38.2 +/- 1.4 respectively. The inhibition mode of citrate is competitive with Fru 2,6-P2, but non-linear in relation of increasing concentrations of the inhibitor. The intracellular distribution and concentration of the key regulatory metabolite Fru 2,6-P2 was further investigated in citrus leaves and juice cells. Fru 2,6-P2 was only found in the cytosol of juice cells. Fru 2,6-P2 was detected under both conditions with higher concentrations found under aerobiosis.

Physical and Kinetic Evidence for an Association between Sucrose-Phosphate Synthase and Sucrose-Phosphate Phosphatase.

The possible formation of a multienzyme complex between sucrose (Suc)-phosphate synthase (SPS) and Suc-phosphate phosphatase (SPP) was examined by measuring the rates of Suc-6-phosphate (Suc-6-P) synthesis and hydrolysis in mixing experiments with partially purified enzymes from spinach (Spinacia oleracea) and rice (Oryza sativa) leaves. The addition of SPP to SPS stimulated the rate of Suc-6-P synthesis. SPS inhibited the hydrolysis of exogenous Suc-6-P by SPP when added in the absence of its substrate (i.e. UDP-glucose) but stimulated SPP activity when the SPS substrates were present and used to generate Suc-6-P directly in the reaction. Results from isotope-dilution experiments suggest that Suc-6-P was channeled between SPS and SPP. A portion of the SPS activity comigrated with SPP during native polyacrylamide gel electrophoresis, providing physical evidence for an enzyme-enzyme interaction. Taken together, these results strongly suggest that SPS and SPP associate to form a multienzyme complex.

Activation of sucrose-phosphate synthase by a protein factor/sucrose-phosphate phosphatase.

The possible presence of a sucrose-phosphate synthase (SPS) activating/stabilizing factor (SAF) presumably lost during SPS purification was investigated. Rice leaf protein extracts were chromatographed in a DEAE-Sephacel column. SPS activity of previously purified rice enzyme was enhanced to different extent by aliquots of fractions from such column. The activating capacity could not be replaced by albumin, but was nullified by EDTA. When the fractions were boiled or treated with TCA, the activating capacity disappeared suggesting its proteinaceous nature. The presence of 10 microM okadaic acid had no effect on the stimulatory action of SAF on SPS denying the possibility to SAF to be a SPS-phosphatase. Although it overlaps somehow with sucrose synthase (SS) in DEAE-Sephacel fractions, the activating protein factor and SS eluted separately during Sephadex G-200 chromatography. The activating ability was saturable at a fixed SPS concentration and was able to enhance SPS activity from other plant sources. Simultaneous studies on the activities of SPS and sucrose-phosphate phosphatase (SPP), closely linked to SPS, allowed us to suggest that SAF could be SPP. The presence of SAF/SPP did not alter the affinity of SPS for its substrates but helped to reverse the Pi inhibition at low Fru-6-P concentrations. We conclude that SPS may possibly interact with SPP, contributing to a more effective sucrose synthesis.

[Randomized comparative study of induced labor with oxytocin and misoprostol in prolonged pregnancies]. / Estudio comparativo randomizado de inducción de parto con ocitocina y misoprostol en embarazos en vías de prolongación.

UNLABELLED: The efficacy of oxytocin for induction of labor at 41 to 42 weeks of gestational age, was compared with misoprostol (a PGE1 analog) in 100 pregnant women. Half a tablet containing 100 mcg of misoprostol was placed intravaginally in 50 women and the remaining 50 received iv oxytocin (2-32 mU/min). The obstetric features were similar in both groups. Delivery within 24 hours was achieved in 88% of the patients induced with misoprostol and in 72% with oxytocin (p < 0.05). The mean time from induction to delivery was similar, 10.3-10.9 hrs (p NS) and no differences in obstetric and perinatal outcomes were found. Polisystoly with misoprostol, was the only side effect observed in the study (11.4%), and was without neonatal consequences. CONCLUSION: intravaginal misoprostol (100 mcg), is more effective, cheaper and less stressful than IVI oxytocin in post term inductions. The safety profiles of both were similar.

Increased affinity of histamine H1 binding to membranes of human myometrium at the end of pregnancy.

1. The characterization of H1 binding sites in membrane preparations of human myometrium obtained from pregnant and non-pregnant women was performed by using 3H-mepyramine as the radioactive ligand. 2. Saturation curve analysis revealed that 3H-mepyramine is bound to a single class of binding sites. Changes in the H1 site binding parameters were observed at the end of pregnancy, resulting in an increased affinity relative to non-pregnant tissue (Kd: 131.0 +/- 8.8 (non-pregnant) and 72.5 +/- 7.5 (pregnant) nM, n = 6, P < 0.01). 3. A reduction in receptor concentration at the end of pregnancy was also observed, [Bmax: 565.2 +/- 43.7 (non-pregnant) and 309.6 +/- 25.9 (pregnant) fmol/mg prot, n = 6, P < 0.01]. It is possible that this reduction in Bmax could be attributed to a dilution factor due to the increase in membraneous proteins that occurs during gestation.

[Normative parameter characterization for the auditory brainstem response of the normal newborn]. / Caracterizacion de los parametros normativos del potencial evocado auditivo del recien nacido normal.

The auditory brainstem response generated by clicks was studied in 119 normal newborns. One ear was studied in detail at 20, 40 and 60 dBnHL, the other at 20 and 30 dBnHL, increasing the intensity if no response was found. The latency for waves I, III and V in the detailed studied ear was 2.7 +/- .39, 5.4 +/- .44 and 7.7 +/- .48, respectively. 85% of newborns had thresholds for auditory brainstem response less than 40 dBnHL, 54% less than 20 dBnHL and 15% between 40 and 60 dBnHL. These findings are compatible with conductive loss in the higher threshold group and support data from Stockard, regarding high risk groups. Additionally, our data suggests that an adequate level to screen for hearing loss in newborns is between 30 and 40 dBnHL.

Sucrose Phosphate Is Not Transported into Vacuoles or Tonoplast Vesicles from Red Beet (Beta vulgaris) Hypocotyl.

Tonoplast vesicles and vacuoles isolated from red beet (Beta vulgaris L.) hypocotyl accumulated externally supplied [(14)C]sucrose but not [(14)C]sucrose phosphate despite the occurrence of sucrose phosphate phosphohydrolytic activity in the vacuole. The activities of sucrose synthase and sucrose phosphate synthase in whole cell extracts were 960 and 30 nanomoles per milligram protein per minute, respectively; whereas, no sucrose synthesizing activity was measured in tonoplast preparations. The results obtained in this investigation are incompatible with the involvement of sucrose phosphate synthase in the process of sucrose synthesis and accumulation in the storage cells of red beet.

Developmental Transition from Enzymatic to Acid Hydrolysis of Sucrose in Acid Limes (Citrus aurantifolia).

The sucrose breakdown mechanisms in juice sacs of acid lime (Citrus aurantifolia [Christm.] Swing.) were investigated throughout fruit development. All three enzymes of sucrose catabolism (sucrose synthase, acid, and alkaline invertase) are present during the initial stages. The activities of these enzymes declined rapidly and disappeared by stage 5 (80% development) but not before vacuolar pH had decreased to approximately 2.5. At this stage, sucrose breakdown occurs by acid hydrolysis. By attaining a vacuolar pH of 2.5 prior to enzyme disappearance, the cell maintains a continuous ability to break down sucrose throughout ontogeny. Thus, acid limes possess a unique and coordinated system for sucrose breakdown that involves both enzymatic and nonenzymatic pathways.

Vacuolar Acid hydrolysis as a physiological mechanism for sucrose breakdown.

Sucrose breakdown in mature acidic ;Persian' limes (Citrus aurantifolia [Christm.] Swing.) occurred at a rate of 30.6 picomoles per milliliter per day during 9 weeks storage at 15 degrees C. Neither enzyme of sucrose catabolism (sucrose synthase or acid/alkaline invertase) was present in extracts of mature storage tissue. The average vacuolar pH, estimated by direct measurement of sap from isolated vacuoles and by the methylamine method, was about 2.0 to 2.2. In vitro acid hydrolysis of sucrose at physiological concentrations in a buffered solution (pH 2.2) occurred at identical rates as in matured limes. The results indicate that sucrose breakdown in stored mature acidic limes occurs by acid hydrolysis.

Enzyme activities associated with maize kernel amyloplasts.

Activities of the enzymes of gluconeogenesis and of starch metabolism were measured in extracts of amyloplasts isolated from protoplasts derived from 14-day-old maize (Zea mays L., cv Pioneer 3780) endosperm. The enzymes triosephosphate isomerase, fructose-1,6-bisphosphate aldolase, fructose-1,6-bisphosphatase, phosphohexose isomerase, phosphoglucomutase, ADPG pyrophosphorylase, UDPG pyrophosphorylase, soluble and bound starch synthases, and branching enzyme were found to be present in the amyloplasts. Of the above enzymes, ADPG pyrophosphorylase had the lowest activity per amyloplast. Invertase, sucrose synthase and hexokinase were not detected in similar amyloplast preparations. Only a trace of the cytoplasmic marker enzyme alcohol dehydrogenase could be detected in purified amyloplast fractions. In separate experiments, purified amyloplasts were lysed and then supplied with radioactively labeled glucose-6-phosphate, glucose-1-phosphate, fructose-1,6-bisphosphate, dihydroxyacetone phosphate, glucose, fructose, sucrose, and 3-0-methylglucose in the presence of adenosine triphosphate or uridine triphosphate. Of the above, only the phosphorylated substrates were incorporated into starch. Incorporation into starch was higher with added uridine triphosphate than with adenosine triphosphate. Dihydroxyacetone phosphate was the preferred substrate for uptake by intact amyloplasts and incorporation into starch. In preliminary experiments, it appeared that glucose-6-P and fructose-1,6-bisphosphate may also be taken up by intact amyloplasts. However, the rate of uptake and incorporation into starch was relatively low and variable. Additional study is needed to determine conclusively whether hexose phosphates will cross intact amyloplast membranes. From these data, we conclude that: (a) Triose phosphate is the preferred substrate for uptake by intact amyloplasts. (b) Amyloplasts contain all enzymes necessary to convert triose phosphates into starch. (c) Sucrose breakdown must occur in the cytosol prior to carbohydrate transfer into the amyloplasts. (d) Under the conditions of assay, amyloplasts are unable to convert glucose or fructose to starch. (e) Uridine triphosphate may be the preferred nucleotide for conversion of hexose phosphates to starch at this stage of kernel development.