Life-history evolution and the microevolution of intermediary metabolism: activities of lipid-metabolizing enzymes in life-history morphs of a wing-dimorphic cricket

Although a considerable amount of information is available on the ecology, genetics, and physiology of life-history traits, much more limited data are available on the biochemical and genetic correlates of life-history variation within species. Specific activities of five enzymes of lipid biosynthesis and two enzymes of amino acid catabolism were compared among lines selected for flight-capable (LW[f]) versus flightless (SW) morphs of the cricket Gryllus firmus. These morphs, which exist in natural populations, differ genetically in ovarian growth (100-400% higher in SW) and aspects of flight capability including the size of wings and flight muscles, and the concentration of triglyceride flight fuel (40% greater in LW[f]). Consistently higher activity of each enzyme in LW(f) versus SW-selected lines, and strong co-segregation between morph and enzyme activity, demonstrated genetically based co-variance between wing morph and enzyme activity. Developmental profiles of enzyme activities strongly paralleled profiles of triglyceride accumulation during adulthood and previous measures of in vivo lipid biosynthesis. These data strongly imply that genetically based elevation in activities of lipogenic enzymes, and enzymes controlling the conversion of amino acids into lipids, is an important cause underlying the elevated accumulation of triglyceride in the LW(f) morph, a key biochemical component of the trade-off between elevated early fecundity and flight capability. Global changes in lipid and amino-acid metabolism appear to have resulted from microevolutionary alteration of regulators of metabolism. Finally, strong genotype x environment (diet) interactions were observed for most enzyme activities. Future progress in understanding the functional causes of life-history evolution requires a more detailed synthesis of the fields of life-history evolution and metabolic biochemistry. Wing polymorphism is a powerful experimental model in such integrative studies.     

Modulation of SCE induction and cell proliferation by 2-mercaptoethanol in phytohemagglutinin-stimulated rat lymphocytes

2-Mercaptoethanol (2-ME) is used as a medium supplement to enhance the proliferation of lymphocytes culturedin vitro. In this study, we have examined the effects of 2-ME on cell growth and on SCE induction in cultures of unstimulated and phytohemagglutinin (PHA)-stimulated Fischer 344 rat lymphocytes. There were virtually no metaphases detected in cells cultured without PHA. In PHA-stimulated cultures, 2-ME decreased SCE-frequency but it enhanced SCE frequency in the presence of S to 12.5 µM bromodeoxyuridine (BRd U). Both mitotic and replication indices were increased in the PHA/2-ME system. The levels of incorporated exogenous thymidine, in the presence of 2-ME, were relatively low in unstimulated cells, suggesting that 2-ME is not mitogenic for T-cells. However, 2-ME enhanced PHA-induced response of T-cells as evidenced by increased levels of thymidine incorporation into cellular DNA. The growth promoting effects and the decrease in SCE frequency caused by 2-ME upon PHA stimulation indicate that 2-ME may alter the nature of interaction between PHA and cellular activating properties or the replicative processes.Abbreviations BRdU bromodeoxyuridine - FBS fetal bovine serum - SCE sister-chromatid exchanges - HEPES N-2-hydroxyethylpiperazine-N-2-ethane sulfonic acid - IL-2 interleukin-2 - 2-ME 2-mercaptoethanol - PBS phosphate buffered saline - PHA phytohemagglutinin - MI mitotic index - RI replication index - NADH nicotinamide adenine dinucleotide (reduced form)     

Relationship between a long-term treatment of 2-mercaptoethanol and protein metabolism in the ageing rat

Summary Female RLEF1/Lati rats were chronically treated with 2-mercaptoethanol in a dose of 13 g·100 g bw^-1·day^-1 dissolved in drinking water. During a 48-h experiment ¹⁵N-labelled glycine was given orally in a dose of 5 mg ¹⁵N·kg bw^-1 and urine samples were collected and analysed by an emission spectrometric isotope method. Protein synthesis and nitrogen excretion rate constants were calculated according to the three-pool model, and 3-methylhistidine excretion rates were also determined. 2-Mercaptoethanol appears to influence protein metabolism; however, the slower rates of protein synthesis proved to be apparent in almost all groups of treated rats. Protein synthesis and nitrogen excretion rate constants have exceptionally high values in 2-year-old rats, possibly explained by the occurrence of hypercompensation mechanisms in old age. These were reflected by the excretion rates of 3-methylhistidine which were reduced as a result of sulphhydryl group interactions in age-dependent cellular metabolic changes.Abbreviations 2ME 2-mercaptoethanol - 3MeHis 3-methylhistidine - bw body weight - HPLC high performance liquid chromatography - SD standard deviation     

Influence of sodium fluoride and caffeine on the concentration of fluoride ions, glucose, and urea in blood serum and activity of protein metabolism enzymes in rat liver

The aim of the study was examining the effect of fluoride ions and caffeine administration on glucose and urea concentration in blood serum and the activity of protein metabolism enzymes and selected enzymes of the urea cycle in rat liver. The study was carried out using 18 male Sprague-Daowley rats (4.5 mo old). Rats were divided into three groups. Group I received distilled water ad libitum. Group II received 4.9 mg F⁻/kg body mass/d of sodium fluoride in the water, and group III received sodium fluoride (in the above-mentioned dose) and 3 mg/kg body mass/d of caffeine in the water. After 50 d, the rats were anesthetized with thiopental and fluoride ions, glucose, and urea concentration in blood serum were determined. Also determined were the activities of aspartate aminotransferase, alanine aminotransferase glutamate dehydrogenase, ornithine carbamoylotransferase and arginase in liver homogenates. Liver was taken for pathomorphological examinations. The applied doses of F⁻ (4.9 mg/kg body mass/d) and F⁻+ caffeine (4.9 mg F⁻/kg body mass/d+3 mg caffeine/kg body mass/d) resulted in a statistically significant increase of fluoride ion concentration in blood serum, a slight increase of the glucose concentration, and no changes in the concentration of urea in blood serum. This might testify to the absence of kidney lesions for the applied concentrations of F⁻. No change in the functioning of hepatocytes was observed; however, slight disturbances have been noted in the functioning of the liver, connected with the activation of urea cycle, increase of arginase activity, and accumulation of F⁻ in this organ. There was no observed significant influence of caffeine supplementation on the obtained results.     

Effect of vermicompost on nutrition and intermediary metabolism of Colorado potato beetle,Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

Colorado potato beetle (CPB) is the important pest of potato throughout the world. The study showed the effects of vermicompost on nutritional indices, digestive enzyme activities and intermediary metabolism of the larvae and the adults of CPB. Vermicompost affected significantly the efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) in addition to activities of carbohydrases and proteases in both larvae and adults. Amount of total phenol compounds increased in the leaves of the potatoes grown on the soil containing 30% of vermicompost compared to control and it were amended by 15% of vermicompost. In case of intermediary metabolism, activities of aspartate aminotransferase and γ-glutamyl transferase showed no significant differences in the control and the treated larvae, but those were fluctuated upper and lower when 15% of vermicompost was added into growth plots. The amount of low-density lipoproteins (LDL) and high-density lipoproteins (HDL) in the larvae of CPB showed no significant differences among treatments. However, the amounts of LDL, HDL, glycogen and protein of the adults significantly increased using 30% of vermicompost. Results of the current study clearly revealed significant effects on some physiological processes in CPB fed on the plants grown in the different vermicompost treatments.     

Changes in the activities of aldolase and other enzymes for carbohydrate metabolism during embryonic and postembryonic development of Bombyx mori

Eggs at the early stages of embryogenesis and the larval fat body in Bombyx mori were confirmed to have an aldolase (ALD) isozyme type S. Its activity ratio with substrates fructose 1,6-bisphosphate (FBP) and fructose 1-phosphate (F1P) was 3. This isozyme was considered to be in favor of rather efficient utilization of F1P, since eggs in early stages of embryogenesis and the fat body had high activities of NADP-sorbitol dehydrogenase (NADP-SDH) and NAD-sorbitol dehydrogenase (NAD-SDH) responsible for the polyol pathway generating F1P. On the other hand, eggs at the second half of embryogenesis and the larval and adult muscle (plus epidermal cells and cuticle) possessed an ALD isozyme type F, whose FBP/F1P activity ratio was 10, suggesting that F1P utilization is less effective. This is in agreement with the fact that the NADP-SDH and NAD-SDH activities were low and the phosphofructokinase (PFK) activity was high in eggs at these stages and in muscle. Arch. Insect Biochem. Physiol. 36:139–148, 1997. © 1997 Wiley-Liss, Inc.     

Intestinal enzymes activities in isolated villus and crypt cells during postnatal development of the rat

Summary A modification of Weiser's (1973) cell isolation method was used in order to study the developmental pattern of various intestinal enzyme activities in villus and crypt cells of normal rats from 5 days after birth until 8 weeks. Alkaline phosphatase and enterokinase activities were always located in the upper villus zone during postnatal development. Enterokinase activity was higher in the upper villus cells during the third week of life than after this period. Aminopeptidase activity was located in the crypt cells during the first week, its maximum activity remained in this area until the third week. At this time, sucrase activity appeared in the crypt cells, then aminopeptidase and sucrase activities rose to the villus zone during the fourth week. Amylase activity was detected along the entire crypt-villus axis 5 days after birth, reaching maximum activity in crypt cells at the end of the first week and in the upper villus cells after the fourth week. In contrast with the other enzymes studied almost all amylase activity was soluble in the youngest animals whereas at weaning most of the activity appeared in a particulate form in the villus cells. But in the crypt cells the ratio between particulate and soluble form remained unchanged until the adult stage. Various hypotheses are advanced to explain the patterns of evolution of the different enzymes.     

Modulation of cell proliferation and polyamine metabolism in rat liver cell cultures by the iron chelator O-trensox

The antiproliferative effects of the iron chelator O-trensox and the ornithine-decarboxylase (ODC) inhibitor alpha-difluoromethylornithine (DFMO) were characterized in the rat hepatoma cell line FAO, the rat liver epithelial cell line (RLEC) and the primary rat hepatocyte cultures stimulated by EGF. We observed that O-trensox and DFMO decreased cell viabilty and DNA replication in the three culture models. The cytostatic effect of O-trensox was correlated to a cytotoxicity, higher than for DFMO, and to a cell cycle arrest in G0/G1 or S phases. Moreover, O-trensox and DFMO decreased the intracellular concentration of spermidine in the three models without changing significantly the spermine level. We concluded that iron, but also polyamine depletion, decrease cell growth. However, the drop in cell proliferation obtained with O-trensox was stronger compared to DFMO effect. Altogether, our data provide insights that, in the three rat liver cell culture models, the cytostatic effect of the iron chelator O-trensox may be the addition of two mechanisms: iron and polyamine depletion.     

Adenosine inhibits activation-induced T cell expression of CD2 and CD28 co-stimulatory molecules: role of interleukin-2 and cyclic AMP signaling pathways

Adenosine is an immunosuppressive molecule that is associated with the microenvironment of solid tumors. Mouse T cells activated with anti-CD3 antibody in the presence of adenosine with or without coformycin (to prevent adenosine breakdown by adenosine deaminase) exhibited decreased tyrosine phosphorylation of some intracellular proteins and were inhibited in their ability to proliferate and synthesize interleukin (IL)-2. In addition, adenosine interfered with activation-induced expression of the co-stimulatory molecules CD2 and CD28. Activation-induced CD2 and CD28 expression was also diminished when T cells were activated in the presence of anti-IL-2 and anti-CD25 antibodies to neutralize IL-2 bioactivity. Collectively, these data suggest that CD2 and CD28 up-regulation following T cell activation is IL-2-dependent; and that adenosine inhibits activation-induced T cell expression of CD2 and CD28 by interfering with IL-2-dependent signaling. The inhibitory effect of adenosine on activation-induced CD2 and CD28 expression could not be attributed to cyclic AMP (cAMP) accumulation resulting from the stimulation of adenylyl cyclase-coupled adenosine receptors, even though cAMP at concentrations much higher than those generated following adenosine stimulation was inhibitory for both CD2 and CD28 expression. We conclude that adenosine interferes with IL-2-dependent T cell expression of co-stimulatory molecules via a mechanism that does not involve the accumulation of intracellular cAMP.     

CO2和O3浓度升高及其复合作用对玉米（Zea mays L.）活性氧代谢及抗氧化酶活性的影响

为了揭示CO2和O3浓度升高及其复合作用对植物活性氧(ROS)代谢及抗氧化酶活性的影响机理,以玉米(Zea mays L.)为研究材料,利用开顶式气室(OTCs)研究了CO2和O3浓度升高及其复合作用下,玉米叶片活性氧产生速率、含量,膜脂过氧化程度,抗氧化酶活性,净光合速率及玉米籽粒产量的变化.结果表明,在整个生育期内,与对照相比,高浓度CO2((550±20)μmol · mol-1)处理下,玉米叶片净光合速率升高,O- ·2 产生速率、H2O2含量下降, MDA含量、相对电导率减小,SOD、CAT、POD活性增强,玉米百粒重和穗粒数增加;而在O3浓度为(80±10)nmol · mol-1的条件下,玉米叶片净光合速率下降,O- ·2 产生速率、H2O2含量升高,MDA含量、相对电导率增大,SOD、CAT、POD活性减弱,玉米百粒重和穗粒数降低;CO2和O3浓度升高复合((550±20)μmol · mol-1 (80±10)nmol · mol-1)处理下,玉米叶片的净光合速率、H2O2含量、SOD活性先升高后降低, MDA含量、相对电导率、CAT活性增加,POD活性减弱,而O- ·2 产生速率几乎不变化,且玉米的百粒重和穗粒数略低于对照.以上结果说明,CO2浓度升高抑制了玉米叶片活性氧的代谢速率,提高了抗氧化酶的活性,从而增强了光合作用,使玉米籽粒产量增加,对玉米表现为保护效应,而O3浓度升高促进了玉米叶片活性氧的代谢速率,降低了抗氧化酶的活性,抑制了光合作用,使玉米籽粒产量下降,对玉米表现为伤害效应.在CO2和O3浓度升高复合处理下,CO2浓度升高在一定程度上缓解了O3浓度升高对玉米的伤害效应,而O3浓度升高亦在一定程度上削弱了CO2浓度升高对玉米的保护效应.     

大鼠肺细小动脉平滑肌细胞培养新方法的建立及血小板衍生因子对其增殖迁移的影响

目的：建立一种操作简单、实验仪器要求低的大鼠肺细小动脉平滑肌细胞（PASMCs）分离和培养的方法,并且探索血小板衍生因子（PDGF）介导的增殖、迁移的情况。方法：向右心注射铁及琼脂糖,利用琼脂糖能同时粘附血管内皮细胞、平滑肌细胞及铁粉,再结合胶原酶I的消化,通过磁力架吸引铁,特异性地分选出带血管的肺组织,经过3~4周左右的培养及纯化,得到肺细小动脉平滑肌细胞。用倒置相差显微镜观察细胞形态,免疫细胞化学法和免疫荧光染色法进行α-平滑肌肌动蛋白鉴定。MTT实验和划痕实验检测PDGF诱导的肺动脉细小平滑肌细胞的增殖和迁移。结果：分离后第14天、第21天及传代后进行鉴定,均表明分离培养的细胞为PASMCs。MTT结果表明,与不加PDGF组相比,PDGF增殖明显增加（P<0.05）。划痕实验结果显示PDGF刺激组比不刺激组迁移显著增多。结论：本方法分离培养大鼠的PASMCs,操作方便,实验仪器要求低。PDGF能够促进肺细小动脉平滑肌细胞的增殖、迁移。     

Effects of harman and norharman on the metabolism and genotoxicity of 2-acetylaminofluorene in cultured rat hepatocytes

Monolayers of rat hepatocytes metabolize 0.25 m M 2-acetylaminofluorene (AAF) to various ether-extractable, water-soluble as well as covalently bound products. The major ether-extractable metabolite formed is 2-aminofuorene (AF), followed by 7-OH-AAF and 9-OH-AAF. Pretreatment of rats with the inducer Aroclor 1254 (PCB) increased the metabolism of AAF and caused an increased DNA repair synthesis in hepatocytes exposed to AAF or AF. With N-OH-AAF, a decreased genotoxic response in PCB-treated cells compared to control cells was seen. The addition of harman and norharman decreased the metabolism of AAF to ether-extractable metabolites, water-soluble metabolites and metabolites covalently bound to macromolecules. In contrast, the DNA-repair synthesis caused by the same concentrations of AAF was increased by harman. One explanation for this apparent discrepancy could be that the aromatic amines changed the metabolism of harman and norharman in such a way that these compounds were converted into genotoxic metabolites.Abbreviations AAF 2-acetylaminofluorene - AF 2-aminofluorene - DMSO dimethylsulfoxide - HPLC high performance liquid chromatography - N-OH-AAF N-ydroxy-2-acetylaminofluorene - PCB polychlorinated biphenyls, Aroclor 1254 - TCDD 2,3,7,8-tetrachlorodibenzo-p-dioxin - TdR thymidine - Trp-P-1 3-amino-1,4dimethyl-5H-pyrido(4,3b)indole - Trp-P-2 3-amino-l-methyl-5H-pyrido(4,3b)indole - UDS unscheduled DNA synthesis     

Growth and activities of enzymes of primary metabolism in batch cultures of Catharanthus roseus cell suspension under different pCO2 conditions

In vitro enzyme activities of glycolysis, pentose-phosphate pathway and dark CO₂ fixation were assayed in batch cultures of heterotrophic Catharanthus roseus cells under various gassing rates and partial pressures of carbon dioxide. Detrimental effects of low pCO₂ culture conditions on the growth characteristics could be linked to marked changes in levels of enzymes of primary metabolism during growth. The enzyme levels observed during the early stages of growth were found to be more stable when a constant pCO₂ (20 mbar) was maintained and enabled exponential growth to be reached more rapidly.The importance of carbon dioxide as a conditioning factor of the culture medium is discussed.     

Analysis of the ammonia metabolism of rat primary hepatocytes and a human hepatocyte cell line Huh 7

Ammonia metabolism of ratprimary hepatocytes and a human hepatocyte cell line,Huh 7, at different concentrations of glutamine,glucose and ammonia was examined. During theincubation of the primary hepatocyte cells, glutamineand ammonia concentrations decreased, that of ureaincreased, and that of glucose remained the same. Inthe case of Huh 7 cells, glucose was consumed rapidly,the concentration of ammonia increased and that of urearemained the same. The major energy sources amongmedium components were glutamine for the primary cellsand glucose for Huh 7 cells, although the primaryhepatocytes may utilize intracellular glycogen asenergy source. As the glutamine concentration in theincubation medium increased, the specific rates of notonly glutamine consumption, but also ammonia productionby the primary cells and Huh 7 cells increased. Besides, specific urea production rate by the primarycells increased then. Increase of glucoseconcentration had no effect on glutamine and ammoniametabolism by both cells, although it increased glucoseconsumption by Huh 7 cells. The incubation of theprimary cells with higher ammonia concentrationincreased all specific rates of glutamine consumption,ammonia consumption and urea production. An increasein the ammonia concentration to 5 mM changed theammonia metabolism from production to consumption andincreased the specific glucose consumption rate. Consequently, increases in the glutamine and ammoniaconcentrations were revealed to have negative andpositive effects, respectively, on decreasing ammoniaconcentration by both of rat primary hepatocytes andHuh 7 cells.     

Human hepatocyte and kidney cell metabolism of 2-acetylaminofluorene and comparison to the respective rat cells

The metabolism and mutagenic activation of 2-acetylaminofluorene by human and rat hepatocytes and kidney cells were measured. High performance liquid chromatography was used to separate the 2-acetylaminofluorene metabolites, and a cell-mediated Salmonella typhimurium mutagenesis assay was used to detect mutagenic intermediates. Rat and human differences were observed with cells from both organs and levels of metabolism and mutagenesis were higher in human cells. Within a species, liver and kidney cell differences were also evident, with levels of hepatocyte-mediated metabolism and mutagenesis being greater than kidney cells. Human inter-individual variation was apparent with cells from both organs, but the variation observed was significantly greater in hepatocytes than kidney cells. A knowledge of such differences, including an understanding that they may vary with the chemical being studied, should be useful in the extrapolation of rodent carcinogenesis data to humans.Abbreviations AAF 2-acetylaminofluorene - AF 2-aminofluorene - DMSO dimethylsulfoxide - HPLC high performance liquid chromatography - N-OH-AAF N-hydroxy-2-acetylaminofluorene - 1-OH-AAF 1-hydroxy-2-acetylaminofluorene - 3-OH-AAF 3-hydroxy-2-acetylaminofluorene - 5/9-OH-AAF a combination of 5 and 9-hydroxy-2-acetylaminofluorene - 7-OH-AAF 7-hydroxy-2-acetylaminofluorene - 8-OH-AAF 8-hydroxy-2-acetylaminofluorene     

Brain pyruvate recycling and peripheral metabolism: an NMR analysis ex vivo of acetate and glucose metabolism in the rat

The occurrence of pyruvate recycling in the rat brain was studied in either pentobarbital anesthetized animals or awake animals receiving a light analgesic dose of morphine, which were infused with either [1-13C]glucose + acetate or glucose + [2-13C]acetate for various periods of time. Metabolite enrichments in the brain, blood and the liver were determined from NMR analyses of tissue extracts. They indicated that: (i) Pyruvate recycling was revealed in the brain of both the anesthetized and awake animals, as well as from lactate and alanine enrichments as from glutamate isotopomer composition, but only after infusion of glucose + [2-13C]acetate. (ii) Brain glucose was labelled from [2-13C]acetate at the same level in anaesthetized and awake rats (approximately 4%). Comparing its enrichment with that of blood and liver glucose indicated that brain glucose labelling resulted from hepatic gluconeogenesis. (iii) Analysing glucose 13C-13C coupling in the brain, blood and the liver confirmed that brain glucose could be labelled in the liver through the activities of both pyruvate recycling and gluconeogenesis. (iv) The rate of appearance and the amount of brain glutamate C4-C5 coupling, a marker of pyruvate recycling when starting from [2-13C]acetate, were lower than those of brain glucose labelling from hepatic metabolism. (v) The evaluation of the contributions of glucose and acetate to glutamate metabolism revealed that more than 60% of brain glutamate was synthesized from glucose whereas only 7% was from acetate and that glutamate C4-C5 coupling was mainly due to the metabolism of glucose labelled through hepatic gluconeogenesis. All these results indicate that, under the present conditions, the pyruvate recycling observed through the labelling of brain metabolites mainly originates from peripheral metabolism.     

BSAP／Pax—5在B淋巴细胞发育、增殖、分化中的作用

BSAP,一个B细胞特异性激活蛋白,由Pax-5转录的核蛋白。作为核转录因子,其在B细胞的发育、增殖和分化中起重要作用。同时也影响B细胞分化晚期的Ig的分泌。     

Effects of factors from ovarian follicular fluid and Sertoli cell culture medium on in-vivo and in-vitro release of pituitary gonadotrophins in the rat: an evaluation of systems for the assay of inhibin.

Inhibin-like activity is present both in testicular and ovarian fluids. Various methods can be used for the detection of this activity. Indirect methods, using organ weights as an endpoint, lack the specificity required for reliable estimation of inhibin-like activity. With in-vivo bioassay systems, using estimation of circulating concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in intact or gonadectomized, immature or adult, male or female rats, a suppression of FSH concentrations only is usually observed after injection of inhibin-like material. The largest suppression of FSH concentrations can be obtained in short-term gonadectomized adult female or 35-day-old male rats. Addition of inhibin-like activity to cultured pituitary cells specifically suppresses the spontaneous release of FSH from the cells. After stimulation of cultured pituitary cells with LH-releasing hormone (LH-RH), the release of both FSH and LH are suppressed when inhibin-like activity is present. From dialysis experiments it appears that the molecular weight of the inhibin-like material in follicular fluid is greater than 10 000. However, acid ethanol extracts of this fluid contain a factor with a molecular weight smaller than 10 000, which does not suppress the spontaneous release of FSH from cultured pituitary cells, but diminishes the LH-RH-stimulated release of both LH and FSH. Furthermore, both follicular fluid and Sertoli cell culture medium can stimulate the release of FSH and LH from pituitary cells when these are cultured without addition of fetal calf serum. These results suggest that gonadal fluids contain several non-steroidal factors which can influence the release of gonadotrophins from pituitary cells.     

Effect of androgens and antiandrogens on the development of the myoid cells of the rat seminiferous tubules (organ culture)

Summary To study the regulation of the development of myoid cells, seminiferous tubules of adult and prepubertal rats were grown in organ culture under the influence of testosterone, HCG and cyproterone acetate. Contractility, EM-structure and histochemical activities of alkaline phosphatase and ATPase of the myoid cells were studied in the adult rat tubules at one week intervals up to 5 weeks in culture, in the prepubertal rat tubules at the age of 15 days and after 15 and 21 days in culture. As in vivo, contractions appear in cultured tubules of prepubertal rats at the age of 15 days. Testosterone and HCG increase the percentage of contractile tubules and the number of filaments of the myoid cells. Cyproterone acetate inhibits both functional and structural development and tends to decrease the enzyme activities. In the cultured adult rat tubules cyproterone acetate causes disappearance of contractility within one week, while contractions normally are found for 3 weeks. Testosterone and HCG have no notable effects on the contractility of adult rat tubules, but they lengthen the persistence of alkaline phosphatase activity. It is concluded that the maturation and also the functioning of the myoid cells are subject to androgenic regulation.