Hydrogen peroxide is involved in drought stress long-distance signaling controlling early stomatal closure in tomato plants.

It has long been hypothesized that hydrogen peroxide (H2O2) may play an essential role in root-to-shoot long-distance signaling during drought conditions. Thus, to better understand the involvement of H2O2 in drought signaling, two experiments were carried out using tomato plants. In the first experiment, a split-root scheme was used, while in the second experiment, the tomato plants were grown in a single pot and subjected to drought stress. In both experiments, H2O2 and catalase were applied together with irrigation. Control plants continued to be irrigated according to the water loss. In the split-root experiment, it was verified that the application of H2O2 to roots induced a clear reduction in plant transpiration compared to untreated or catalase-treated plants. In the second experiment, we observed that H2O2-treated plants exhibited similar transpiration when compared to untreated and catalase-treated plants under drought stress. Similarly, no difference in water use efficiency was observed. Thus, we conclude that the increase in H2O2 in the root system can act as a long-distance signal leading to reduced transpiration even when there is no water limitation in the shoot. But it has little effect when there is a reduction in the shoot water potential.

Hydrogen peroxide is involved in drought stress long-distance signaling controlling early stomatal closure in tomato plants / O peróxido de hidrogênio está envolvido na sinalização de longa distância do déficit hídrico controlando o fechamento estomático precoce em plantas de tomate

It has long been hypothesized that hydrogen peroxide (H2O2) may play an essential role in root-to-shoot long-distance signaling during drought conditions. Thus, to better understand the involvement of H2O2 in drought signaling, two experiments were carried out using tomato plants. In the first experiment, a split-root scheme was used, while in the second experiment, the tomato plants were grown in a single pot and subjected to drought stress. In both experiments, H2O2 and catalase were applied together with irrigation. Control plants continued to be irrigated according to the water loss. In the split-root experiment, it was verified that the application of H2O2 to roots induced a clear reduction in plant transpiration compared to untreated or catalase-treated plants. In the second experiment, we observed that H2O2-treated plants exhibited similar transpiration when compared to untreated and catalase-treated plants under drought stress. Similarly, no difference in water use efficiency was observed. Thus, we conclude that the increase in H2O2 in the root system can act as a long-distance signal leading to reduced transpiration even when there is no water limitation in the shoot. But it has little effect when there is a reduction in the shoot water potential.

Tem sido hipotetizado que o peróxido de hidrogênio (H2O2) pode desempenhar um papel essencial na sinalização de longa distância entre a raiz e a parte aérea sob condições de seca. Assim, para melhor entender o envolvimento do H2O2 na sinalização da seca, dois experimentos foram realizados com plantas de tomate. No primeiro, foi utilizado o esquema de raízes divididas, enquanto no segundo, os tomateiros foram cultivados em um único vaso e submetidos ao déficit hídrico. Em ambos os experimentos, o H2O2 e a catalase foram aplicados juntamente com a irrigação. As plantas do grupo controle continuaram a ser irrigadas de acordo com a perda de água. No experimento de raiz dividida, verificou-se que a aplicação de H2O2 nas raízes induziu uma clara redução na transpiração da planta em comparação com plantas não tratadas ou tratadas com catalase. No segundo experimento, observamos que plantas tratadas com H2O2 apresentaram transpiração semelhante quando comparadas com plantas não tratadas e tratadas com catalase sob seca. Da mesma forma, não foi observada diferença na eficiência do uso da água. Assim, concluímos que o aumento do H2O2 no sistema radicular pode atuar como um sinal de longa distância levando à redução da transpiração mesmo quando não há limitação hídrica na parte aérea. Mas tem pouco efeito quando há redução do potencial hídrico da parte aérea.

Regulation and action of fibroblast growth factor 17 in bovine follicles.

Fibroblast growth factor 17 (FGF17) is a member of the FGF8 subfamily that appears to be relevant to folliculogenesis and oogenesis, as the prototype member FGF8 is an oocyte-derived protein that signals to cumulus cells. FGF8 has structural and receptor-binding similarities to FGF17, whose expression in the ovary has not been reported. In this study, we demonstrate localization of FGF17 protein to the oocyte of preantral follicles, and to the oocyte and granulosa cells of antral follicles. Real-time PCR demonstrated the presence of mRNA in oocytes and, to a lesser extent, in granulosa and theca cells. FGF17 mRNA abundance was low in granulosa and theca cells from healthy follicles and increased significantly in atretic follicles. Addition of FSH or IGF-I to granulosa cells in vitro decreased FGF17 mRNA abundance, and treatment with FGF17 inhibited estradiol and progesterone secretion from granulosa cells in relation to control cultures without these additives. We conclude that FGF17 is a potential mediator of granulosa cell differentiation.

Expression of fibroblast growth factor 13 (Fgf13) mRNA in bovine antral follicles and corpora lutea

Recent studies have suggested a paracrine role for several fibroblast growth factors (FGFs) in the regulation of follicle and luteal development. Fgf13 is a non-secreted FGF that has been previously localized to the developing gonads, but it is not known if it is expressed in the adult ovary. The objective of the present study was to determine the expression pattern of Fgf13 mRNA in the bovine ovary. Fgf13 mRNA expression was examined by semiquantitative RT-PCR using Gapdh as the internal control gene in theca and granulosa cells, corpora lutea (CL) and oocytes collected from abattoir ovaries. Follicles were grouped according to estradiol content (<5, 5-20, >20-100 and >100 ng/ml) and size (5-7, 8-10 and >10 mm diameter). CL samples were morphologically classified into four developmental stages. Fgf13 mRNA expression was assessed in pools containing 50 oocytes aspirated from follicles larger than 4 mm in diameter. ANOVA was used to test for the main effects of follicle size group, and estradiol concentration group in granulosa and theca cells, and to test the effect of CL developmental stage on Fgf13 mRNA abundance. Fgf13 mRNA was detected in the CL and in somatic follicle cells, but not in oocytes. Thecal Fgf13 expression increased with increasing follicle diameter but did not change with intrafollicular estradiol concentrations. No evidence of developmental regulation of Fgf13 mRNA expression was observed in granulosa cells and CL. The present data demonstrate for the first time the expression of an intracellular FGF in the bovine ovary and suggests that Fgf13 mRNA is upregulated in bovine theca cells during antral follicle growth.(AU)

Expression of fibroblast growth factor 13 (Fgf13) mRNA in bovine antral follicles and corpora lutea

Recent studies have suggested a paracrine role for several fibroblast growth factors (FGFs) in the regulation of follicle and luteal development. Fgf13 is a non-secreted FGF that has been previously localized to the developing gonads, but it is not known if it is expressed in the adult ovary. The objective of the present study was to determine the expression pattern of Fgf13 mRNA in the bovine ovary. Fgf13 mRNA expression was examined by semiquantitative RT-PCR using Gapdh as the internal control gene in theca and granulosa cells, corpora lutea (CL) and oocytes collected from abattoir ovaries. Follicles were grouped according to estradiol content (20-100 and >100 ng/ml) and size (5-7, 8-10 and >10 mm diameter). CL samples were morphologically classified into four developmental stages. Fgf13 mRNA expression was assessed in pools containing 50 oocytes aspirated from follicles larger than 4 mm in diameter. ANOVA was used to test for the main effects of follicle size group, and estradiol concentration group in granulosa and theca cells, and to test the effect of CL developmental stage on Fgf13 mRNA abundance. Fgf13 mRNA was detected in the CL and in somatic follicle cells, but not in oocytes. Thecal Fgf13 expression increased with increasing follicle diameter but did not change with intrafollicular estradiol concentrations. No evidence of developmental regulation of Fgf13 mRNA expression was observed in granulosa cells and CL. The present data demonstrate for the first time the expression of an intracellular FGF in the bovine ovary and suggests that Fgf13 mRNA is upregulated in bovine theca cells during antral follicle growth.

Expression of fibroblast growth factor-8 and regulation of cognate receptors, fibroblast growth factor receptor-3c and -4, in bovine antral follicles.

Paracrine cell signaling is believed to be important for ovarian follicle development, and a role for some members of the fibroblast growth factor (FGF) family has been suggested. In the present study, we tested the hypothesis that FGF-8 and its cognate receptors (FGFR3c and FGFR4) are expressed in bovine antral follicles. RT-PCR was used to analyze bovine Fgf8, Fgfr3c and Fgfr4 mRNA levels in oocytes, and granulosa and theca cells. Fgf8 expression was detected in oocytes and in granulosa and theca cells; this expression pattern differs from that reported in rodents. Granulosa and theca cells, but not oocytes, expressed Fgfr3c, and expression in granulosa cells increased significantly with follicle estradiol content, a major indicator of follicle health. Fgfr4 expression was restricted to theca cells in the follicle, and decreased significantly with increasing follicle size. To investigate the potential regulation of Fgfr3c expression in the bovine granulosa, cells were cultured in serum-free medium with FSH or IGF-I; gene expression was upregulated by FSH but not by IGF-I. The FSH-responsive and developmentally regulated patterns of Fgfr3c mRNA expression suggest that this receptor is a potential mediator of paracrine signaling to granulosa cells during antral follicle growth in cattle.

Expression of fibroblast growth factor-8 and its cognate receptors, fibroblast growth factor receptor (FGFR)-3c and-4, in fetal bovine preantral follicles.

Paracrine cell signaling is thought to be important for ovarian follicle development, and a role for some members of the fibroblast growth factor (FGF) family have been suggested. In the present study, we tested the hypothesis that FGF-8 and its cognate receptors (FGFR-3c and FGFR-4) are expressed in bovine preantral follicles. Reverse transcription-polymerase chain reaction was used to amplify bovine FGF-8, FGFR-3c, and FGFR-4 from preantral follicle samples and a variety of fetal and adult tissues. All three genes were widely expressed in fetal tissues, with a restricted expression pattern in adult tissues. FGF-8 and FGFR-3c were expressed in secondary follicles in 70% of fetuses examined, whereas FGFR-4 expression was significantly less frequent (20%). FGFR-3c expression frequency was significantly lower in primordial compared to secondary follicles, and FGF-8 expression showed a similar trend. FGFR-4 was only observed when all follicle classes of an individual were expressing both FGF-8 and FGFR-3c. We conclude that FGF-8 and its receptors are expressed in preantral follicles in a developmentally regulated manner.