First Phase Of Growth Research Articles

The initiation of follicle growth: the oocyte or the somatic cells?

The initiation of follicle growth is defined as the transition of primordial follicles from the quiescent to the growth phase. We have shown that follicle growth initiation consists of two distinct, consecutive phases. The first phase is characterized by the transformation of granulosa cells from flattened to cuboidal in shape and by their proliferation, this coincides with follistatin expression. During the second phase, an increase in the number of granulosa cells is accompanied by an increase in the size of the oocyte. Evidence from other species confirms this observation. It seems that a prerequisite for initiation of oocyte growth is the presence of cuboidal granulosa cells. The vast majority of bovine primordial follicles enter the first phase of growth when cultured in serum-free medium. Similar results have been obtained for human primordial follicles. Two proteins of oocyte origin, GDF9 and BMP15, play an essential role in granulosa cell proliferation beyond the primary stage. It can be speculated that the regulation of follicle growth initiation is a two-phase event: the first phase depends on locally produced inhibitory and stimulatory factor(s); in the second phase the follicle become an autonomous unit, whose further development depends on oocyte-produced GDF9/BMP15 and the kit ligand derived from granulosa cells.

WATER RELATIONS, CALCIUM AND POTASSIUM CONCENTRATION IN FRUITS AND LEAVES DURING ANNUAL GROWTH IN MATURE KIWIFRUIT PLANTS

WATER RELATIONS, CALCIUM AND POTASSIUM CONCENTRATION IN FRUITS AND LEAVES DURING ANNUAL GROWTH IN MATURE KIWIFRUIT PLANTS

Diffusion mediated film growth on polycrystalline substrates

Mechanisms of island formation and growth are central issues in thin-film deposition. The shape and size as well as the spatial distribution of stable islands in the first phases of growth determine a wide variety of film properties. In an earlier work, the growth mode of sputter-deposited tin (Sn) and lead (Pb) films on polycrystalline Al substrates was analyzed in the framework of the rate-equation theory. This analysis yielded Stranski–Krastanov growth with the size of the critical nucleus in the range from 6 to 20 monomers. The present study is devoted to a detailed experimental investigation of the mechanisms involved in the formation of Sn and Pb islands on polycrystalline aluminum (Al). All thin-film systems treated in this work were deposited on glass substrates by DC magnetron sputtering. They consist of a polycrystalline Al underlayer covered with a 100 Å thick Sn or Pb films. The variation of the mean Sn and Pb island distance was determined as a function of the deposition temperature and of the underlayer thickness. It varied from 0.5 to 20 μm and showed an Arrhenius dependence on the deposition temperature. A rate-equation analysis yielded activation energies for surface diffusion of single Sn and Pb atoms of approximately 0.5 eV. Island size distributions (ISDs) were determined for different deposition temperatures and were mostly found to be monomodal with a global maximum at the mean island size. All these facts indicate that the mechanism of island formation is mediated by surface diffusion of the Sn or Pb monomers on the Al surface in a wide range of deposition temperatures.

The application of rate equations to describe nucleation and growth on rough substrates: tin and lead on aluminium

The description of island nucleation and growth is an essential goal in thin film deposition. The shape and the distribution of stable islands in the first phases of growth determines a wide variety of film properties. Because of their mean-field nature rate equations are a powerful tool for the analysis of nucleation and growth phenomena if local properties of the substrate are of minor importance. Therefore, the rate equation theory is well established for flat, single crystalline surfaces but it can also be applied to substrates with well-defined defects as e.g. vicinal surfaces. This paper shall test the applicability of the rate equation theory for rough substrates. In this case, one expects the validity of a mean-field approach only if the diffusion length of a monomer is significantly larger than the extension of a typical surface feature. Therefore highly mobile species have to be considered. In the present study tin (Sn) and lead (Pb) were sputter-deposited on aluminium (Al) substrates with RMS roughnesses of about 20 nm. Since a distinctive island growth was observed and the island separation was in the μm-range the above statement was presumed to be valid because of the high ratios of island separation/RMS roughness. The growth mode of the Sn and Pb-films on the Al-substrates was analyzed in the framework of the rate equation theory by varying the coverage and deposition rate. For both systems, Sn on Al and Pb on Al, the rate equation analysis yielded Stranski–Krastanov growth with the size of the critical nucleus in the range from 6 to 20 monomers. This result was independently checked by sputter-AES. A thin layer of Sn or Pb was detected between the islands. This wetting layer seems to be highly conformal with the polycrystalline Al according to topographic atomic force microscopic (AFM) measurements. These facts support the Stranski–Krastanov result.

Growth, maturation and ripening of breadfruit, Artocarpus altilis (Park.) Fosb.

Fruit growth of a seedless, `white flesh' cultivar of breadfruit [ Artocarpus altilis (Park.) Fosb.] was single sigmoidal as measured by diameter, but double sigmoidal when assessed as dry or fresh weight. The first phase of growth was characterised by size generation while the second phase involved major increase in dry weight, mainly in the form of starch accumulation. The fruit required 13–21 weeks to reach full size from the time when the female inflorescence was first detectable in the terminal leaf sheath though sensory tests of cooked fruit revealed that only fruit 15–19 weeks old was acceptable. This age range coincided with maturity indices such as the appearance of white latex on the fruit skin and flattening of the fruit segments and the spur at the centre of these. Skin colour could not be reliably used as a maturity index. Mature fruit produced a monophasic respiratory climacteric, with CO 2 production reaching 200 ml kg −1 h −1 at 25–30°C. In contrast, peak ethylene production was low (1.5 μl kg −1 h −1 ). The respiratory climacteric of fruit harvested at the earliest maturity (13-to-15-week-old fruit) tended to be higher and later than that of fully mature (19-to-21-week-old) fruit.

Kinetic Analysis of the Growth Rate of the Flagellar Hook in Salmonella typhimurium by the Population Balance Method

The growth rate of flagellar hooks in Salmonella typhimurium was analyzed by computer-aided simulation of the length distributions of mutant hooks of uncontrolled length (polyhooks). The wild-type hook has a relatively well-controlled length, with an average of 55 nm and a standard deviation of 6 nm. Mutations in the fliK gene give rise to polyhooks. A histogram of the lengths of polyhooks from a fliK mutant shows a peak at 55 nm with a long monotonic tail extending out to 1 μm. To analyze the growth rate, we employed the population balance method. Regression analysis showed that the histogram could fit a combination of two theoretical curves. In the first phase of growth, the hook starts with a very fast growth rate (40 nm/min), and then the rate exponentially slows until the length reaches 55 nm. In the second phase of growth, where the hook length is over 55 nm, the hook grows at a constant rate of 8 nm/min. Second mutations in either the fliK or flhB genes, as found in pseudorevertants from fliK mutants, give rise to polyhook filaments (phf). The ratio between the numbers of hooks with and without filament was 6:4. The calculated probability of filament attachment to polyhooks was low so that the proportion of hooks that start filament growth was only 2% per minute. The lengths of polyhooks with and without filaments were measured. A histogram of hook length in phf's was the same as that for polyhooks in single-site fliK mutants, against the expectation that the distribution would shift to a shorter average. The role of FliK in hook length control is discussed.

Role of Temperature and Photoperiod in the Onset of Sexual Maturity in Female Frogs, Rana cyanophlyctis

Role of Temperature and Photoperiod in the Onset of Sexual Maturity in Female Frogs, Rana cyanophlyctis

Effect of exposure to continuous light and melatonin on ovarian follicular kinetics in the skipper frog, Rana cyanophlyctis.

Ovarian follicular kinetics and gravimetric changes in the ovary and oviducts were studied in the skipper frog, Rana cyanophlyctis, following exposure to continuous light and melatonin treatment during the breeding season. Daily late-afternoon injections of melatonin (15 micrograms subcutaneous) for 30 days decreased the gonadosomatic index (GSI), whereas continuously available melatonin from subcutaneous implants did not influence the GSI compared to those of controls. Exposure to continuous light for 30 days stimulated the GSI, and melatonin given as daily injections prevented the continuous-light induced increase in GSI. Oviductal weights decreased only in the melatonin-injected groups. Data on follicular kinetics revealed a decrease in first-growth-phase (FGP) oocytes and an increase in medium-sized second-growth-phase (MSGP) and large-sized second-growth-phase (LSGP) oocytes following continuous-light exposure. Melatonin administered to continuous-light-exposed frogs did not change the FGP oocyte number; however, it reduced both the MSGP and LSGP oocytes. Melatonin administration to frogs held in a light and dark cycle increased FGP oocytes and decreased MSGP and LSGP oocytes. Atretic follicles increased in all melatonin-treated groups. The results suggest that continuous light stimulates and melatonin inhibits reproductive function in this species.

Ovarian Follicular Kinetics in Response to Enucleation and Parietal Shielding inRana cyanophlyctis

Ovarian follicular kinetics, gravimetric changes in the ovary and the oviduct, were studied in the skipper frog,Rana cyanophlyctis,following enucleation (ENX) and parietal shielding (PS), during the breeding reason. PS was to prevent extraoptic photoreception by the pineal via the frontal organ. The gonadosomatic index (GSI) was high in ENX and PS frogs (P<0.01). The highest GSI occurred in frogs that were both ENX and PS (P<0.01). Percentage of oviductal weight decreased (P<0.01) in PS frogs and increased (P<0.01) in those subjected to both ENX and PS. Oviductal weight of ENX frogs was unchanged. Data on follicular kinetics revealed a decrease (P<0.01) in the ENX group in the number of first growth phase (FGP) oocytes and atretic follicles (AF), whereas the number of medium-sized secondary growth phase (MSGP) oocytes and large-sized secondary growth phase (LSGP) oocytes increased (P<0.01). There was a similar pattern of follicular kinetics in ENX+PS frogs. However, following PS, the number of FGP oocytes and AF increased (P<0.01) and decreased (P<0.01) in the MSGP and LSGP oocytes. The lower oviductal weight in PS frogs correlated with reduced SGP oocytes, the major source of estrogen. The importance of lateral eyes and the frontal organs in the transduction of environmental signals to the neuroendocrine–reproductive axis is indicated in this species. That recruitment of FGP to SGP is inhibited only in the PS group suggests that the frontal organ plays an important role in ovarian follicular kinetics.

Growth kinetics of vitis vinifera cell suspension cultures: I. Shake flask cultures

Vitis vinifera cell suspension cultures carried out in shake flasks were closely examined for biomass growth and cell division in relation to carbohydrate, NH(4), NO(3)PO(4), and dissolved oxygen (DO)consumption. After inoculation, the oxygen uptake rate of the cultures measured on-tine was observed to increase continuously to a maximum value of 3.8 mmol O(2)L(-1)h(-1) at day 7 when cell division ceased and dissolved oxygen reached its lowest level of 17% air saturation. During this first phase of growth, the specific oxygen uptake rate remained constant at approximately 0.6 mmol 02 O(2) g(-1) dw h(-1)or approximately 2.2 mumol O(2), (10(6) cells)(-1) h(-1) whereas dry biomass concentration increased exponentially from 1.5 to 6.0 g dw L(-1). Thereafter, dry biomass concentration increased linearly to approximately 14 g dw L(-1) at day 14 following nitrate and carbohydrate uptake. During this second phase of growth, the biomass wet-to-dry weight ratio was found to increase in an inverse relationship with the estimated osmotic pressure of the culture medium. This corresponded to inflection points in the dry and wet biomass concentration and packed cell volume curves. Furthermore, growth and nutrient uptake results suggest that extracellular ammonium or phosphate ion availability may limit cell division. These findings indicate that cell division and biomass production of plant cell cultures may not always be completely associated, which suggests important new avenues to improve their productivity. (c) 1995 John Wiley & Sons, Inc.

Diauxic Growth of Azotobacter vinelandii on Galactose and Glucose: Regulation of Glucose Transport by Another Hexose

The growth curve of Azotobacter vinelandii was biphasic when the organism was grown in a medium containing a mixture of galactose and glucose. Galactose was the primary carbon source; glucose was also consumed, but the rate at which it was consumed was lower than the rate at which galactose was consumed during the first phase of growth. Metabolic pathways for both sugars were induced. Cell cultures exhibited a second lag period as galactose was depleted. The length of this lag phase varied from 2 to 10 h depending on the pregrowth history of the cells. The second log growth phase occurred at the expense of the remaining glucose in the medium and was accompanied by induction of the high-maximum rate of metabolism glucose-induced glucose permease and increases in the levels of glucose metabolic enzymes. The second lag phase of diauxie may have been due to the time required for induction of the glucose-induced glucose permease.

Biodelignification and Changes inin vitroDigestibility of Sugarcane Bagasse Treated with White Rot Fungi

Abstract Kamra, D.N., Kewalramani, N., Lall, D. and Pathak, N.N. 1993. Biodelignification and changes in in vitro digestibility of sugarcane bagasse treated with white rot fungi. J. Appl. Anim. Res., 4: 133–140. The biodegradation of sugarcane bagasse and its components by different strains of white rot fungi i.e. Stropharia rugosoannulata, Ganoderma lucidum, Pleurotus ostreatus, Pleurotus—131, Pleurotus—137, Pleurotus P7H7, Polyporus versicolor, Polyporus adustus, Polyporus sanguineus and Polyporus cinnibarinus was studied. During the first phase of growth (0–20 days) hemicellulose was selectively degraded whereas during the second phase (21–40 days) lignin was preferentially degraded in comparison to the other substrate components. The maximum degradation of dry matter was observed in Polyporus sanguineus treated group, but lignin degradation was highest by Polyporus versicolor. The largest increase in in vitro digestibility and nutrient availability was observed on Ganoderma lucidum treatment. Among th...

Atropine metabolism by a Pseudimanas sp.: Diauxic growth and oxidation of the products from esterase-mediated cleavage

Pseudomonas AT3 was isolated by elective culture with atropine as sole carbon source. Growth on atropine involved cleavage of the ester bond and was diauxic, with tropic acid being used in the first phase of growth followed by growth on the accumulated tropine moiety. During growth in N-limited medium, tropic acid was still used preferentially, nitrogen was provided from the tropine and novel keto compounds accumulated in the media. An inducible atropine esterase was synthesized during growth on atropine and, to a lesser extent, during growth on tropic acid and tropine. Organisms harvested from either phase of diauxic growth were able to oxidise tropic acid atropine. The ability of Pseudomonas AT3 to oxidase tropine was evident only in the second phase of growth and the greater extent of atropine oxidation in this phase reflected the ability to oxidase both cyclic components.

Effects of atmospheric CO2 enrichment on early growth of Vivia faba, a plant with large cotyledons

ABSTRACTSeedlings of Vicia faba L. were grown in open‐top growth chambers at present (P=350μmol−1) and at elevated (E=700μmol mol−1) atmospheric CO2 concentration. The effects of CO2 enrichment on the first phase of growth after germination were examined over 45 d. There were no positive effects of CO2 enrichment on growth of the seedlings during this early phase. No differences were observed in leaf area or in total dry weight. No differences were found in morphology or anatomy of the leaves. The numbers of stomatal and epidermal cells, thickness of leaf, of epidermis and of mesophyll cell‐layers were unaffected by CO2 enrichment. Also, no differences were observed in leaf concentrations of chlorophyll, reducing carbohydrates or starch. These results contrast markedly with results from similar experiments on poplar hybrids and Phaseolus vulgaris obtained in the same growth facility. It seems that the intitial growth is under internal control such that the atmospheric CO2 concentration has no effects. The lack of response in this case may be attributed to the presence and longevity of the large cotyledons which provided available substrate for growth.

Atropine metabolism by aPseudimanassp.: Diauxic growth and oxidation of the products from esterase-mediated cleavage

Pseudomonas AT3 was isolated by elective culture with atropine as sole carbon source. Growth on atropine involved cleavage of the ester bond and was diauxic, with tropic acid being used in the first phase of growth followed by growth on the accumulated tropine moiety. During growth in N-limited medium, tropic acid was still used preferentially, nitrogen was provided from the tropine and novel keto compounds accumulated in the media. An inducible atropine esterase was synthesized during growth on atropine and, to a lesser extent, during growth on tropic acid and tropine. Organisms harvested from either phase of diauxic growth were able to oxidise tropic acid atropine. The ability of Pseudomonas AT3 to oxidase tropine was evident only in the second phase of growth and the greater extent of atropine oxidation in this phase reflected the ability to oxidase both cyclic components.

Growth of thermophilic bacteria in rapemeal‐derived media

K.H. YEOMAN AND C. EDWARDS. 1992. A clarified, soluble, protein‐rich medium was developed from rapemeal by boiling with 0·1 mmol/1 NaOH. The medium contained 78% of the original meal protein and supported the growth of a range of thermophilic micro‐organisms that included Bacillus, Streptomyces and fungi. Amino acid analysis of the medium showed a full range of amino acids, and that acidic ones such as glutamate predominated. Growth of a thermophilic Bacillus spp. (termed 1/15) in the medium was biphasic and significant amounts of extracellular protease were synthesized during the scond growth phase. Biphasic growth was probably due to preferential utilization of free amino acids during the first phase of growth followed by degradation of proteins during the second phase.

The ovarian cycle in the natterjack toad, Bufo calamita, and its relation to breeding behaviour

Abstract The ovarian cycle in natterjack toads Bufo calamita from an island population with unpredictable breeding conditions was studied in an archipelago off the Swedish west coast. About 80% of the female population bred during spring and early summer, and the rest later in summer and early autumn. Time of breeding and female size (age) were not correlated. It was found that first growth phase (FGP) oocytes were recruited from oogonia mainly during early spring and late autumn, but that recruitment could occur at any time of the year. The FGP oocytes grew rapidly immediately after recruitment, and when transferred into second growth phase (SGP) oocytes. In between these two periods the FGP oocytes seemed to be in a resting stage. Females showed an asynchrony in ovarian developed. We found females with fully developed SGP oocytes, ready for ovulation, as well as females with ovaries in only an early vitellogenic growth phase at all times of the year. Females did not neccessarily ovulate as soon as the vitellogenic oocytes had reached full size. There were strong indications that some females only ovulated and laid a fraction of the egg mass in their first batch, and that they laid a second batch later in the season. This second batch was thought to originate from the same recruitment of oocytes as the first batch. There was a tendency for SGP oocytes to grow faster during summer than during spring. It was also concluded that SGP oocytes coulde be recruited all year around. Bimodal size frequency distribution patterns were found both among the FGP and the SGP oocytes; they were most pronounced among the latter, where they were found throughout the year.

Control of diauxic growth of Azotobacter vinelandii on acetate and glucose

Batch cultures of Azotobacter vinelandii were inoculated with cells pregrown on either acetate or glucose. When they were subsequently grown on a mixture of acetate and glucose, typical diauxic growth was observed, with preferential uptake of acetate in the first and glucose in the second phase of growth. Extracts from acetate-pregrown cells exhibited high acetate kinase activity in the first phase of growth. This activity decreased and activities of the two glucose enzymes glucose 6-phosphate dehydrogenase and glyceraldehyde 3-phosphate dehydrogenase increased in the second phase. Extracts from glucose-pregrown cells exhibited high initial activities of the two glucose enzymes, which decreased while acetate kinase activity increased in the first phase of growth. Again, in the second phase, activities of the two glucose enzymes increased and acetate kinase activity decreased. In any case, isocitrate dehydrogenase activity varied only slightly and unspecifically. The differences in enzyme activity and the constancy of isocitrate dehydrogenase were confirmed by experiments with either acetate- or glucose-limited chemostats. In chemostats in which both of the substrates were limiting, all of the enzymes displayed significant activities. Glucose 6-phosphate dehydrogenase activity was inhibited by acetyl coenzyme A and acetyl phosphate but not by acetate. It is proposed that diauxic growth is based on the control of enzymes involved in acetate or glucose dissimilation by which acetate or its metabolites control the expression and activity of glucose enzymes.

Diamine Oxidase Activity in Different Physiological Stages of Helianthus tuberosus Tuber

Diamine oxidase (DAO, EC 1.4.3.6) activity was examined in relation to polyamine content in Helianthus tuberosus L. during the first synchronous cell cycle induced in vitro by 2,4,-dichloro-phenoxyacetic acid in tuber slices and during the in vivo formation of the tuber. The optimal pH, buffer and dithiothreitol concentrations for the enzyme extraction and assay were determined. When added in the assay mixture, catalase enhanced DAO activity, while polyvinylpyrrolidone had no effect; both aminoguanidine and hydrazine inhibited enzyme activity. The time course of the reaction, based on the recovery of Delta(1)-pyrroline from labeled putrescine in lipophilic solvents, showed that it was linear up to 30 minutes; the K(m) of the enzyme for putrescine was of the order of 10(-4) molar. During the first cell cycle, DAO activity exhibited a peak at 15 hours of activation while putrescine content gave a peak at 12 hours. During tuber formation (from August till October) DAO activity was relatively high during the first phase of growth (cell division), decreased until flowering (end of September-early October), and then newly increased during the cell enlargement phase preceding the entry into dormancy (November). Maximum putrescine content was observed at the end of October. The increase in DAO activity paralleled the accumulation of putrescine. This indicates a direct correlation between the biosynthesis and oxidation of putrescine which, as already demonstrated in animal systems, occur simultaneously in physiological stages of intense metabolism such as cell division or organ formation.

Mechanisms regulating the ovarian cycle in the frog Rana cyanophlyctis: effect of unilateral ovariectomy, season, feeding, human chorionic gonadotrophin, and estradiol-17 beta.

Effects of 30-day unilateral ovariectomy (ULO) on compensatory ovarian hypertrophy (COH) was studied in adult frog Rana cyanophlyctis in relation to reproductive phase/season, feeding, and treatment with human chorionic gonadotrophin (HCG) or estradiol-17 beta. Compensatory growth of the remaining ovary was assessed in terms of weight as well as changes in the dynamics of the pool sizes of different oocytes viz., first growth phase (FGP), medium-sized second growth phase (MSGP), large-sized second growth phase (LSGP), and atretic oocytes. The frogs were fed with live guppies 6 days a week. The effect of underfeeding on COH was studied in the frogs fed once a week. The ovaries removed at operation and those of the sham-operated frogs were used for comparison (controls). COH occurred in both pre- and postbreeding phases (February and November, respectively). In both instances follicular atresia was greatly reduced. In February, COH was due to recruitment of both MSGP and LSGP oocytes. The number of these oocytes increased significantly over controls, and the ovarian weight nearly doubled. However, in November COH occurred because of an increase in FGP oocytes and therefore total oocytes, but there were no changes in the ovarian weights. Administration of 20 IU HCG (6 days a week) had no influence on the basic pattern of COH-response exhibited by the remaining ovary in relation to reproductive phase/season, but it increased the recruitment of oocytes, i.e., FGP oocytes in November and SGP oocytes in February. Follicular atresia was drastically reduced with HCG. Underfeeding or treatment with estradiol-17 beta abolished the COH in both February and November.(ABSTRACT TRUNCATED AT 250 WORDS)