Seed germination and dormancy traits of forbs and shrubs important for restoration of North American dryland ecosystems.

In degraded dryland systems, native plant community re-establishment following disturbance is almost exclusively carried out using seeds, but these efforts commonly fail. Much of this failure can be attributed to the limited understanding of seed dormancy and germination traits. We undertook a systematic classification of seed dormancy of 26 species of annual and perennial forbs and shrubs that represent key, dominant genera used in restoration of the Great Basin ecosystem in the western United States. We examined germination across a wide thermal profile to depict species-specific characteristics and assessed the potential of gibberellic acid (GA3 ) and karrikinolide (KAR1 ) to expand the thermal germination envelope of fresh seeds. Of the tested species, 81% produce seeds that are dormant at maturity. The largest proportion (62%) exhibited physiological (PD), followed by physical (PY, 8%), combinational (PY + PD, 8%) and morphophysiological (MPD, 4%) dormancy classes. The effects of chemical stimulants were temperature- and species-mediated. In general, mean germination across the thermal profile was improved by GA3 and KAR1 for 11 and five species, respectively. We detected a strong germination response to temperature in freshly collected seeds of 20 species. Temperatures below 10 °C limited the germination of all except Agoseris heterophylla, suggesting that in their dormant state, the majority of these species are thermally restricted. Our findings demonstrate the utility of dormancy classification as a foundation for understanding the critical regenerative traits in these ecologically important species and highlight its importance in restoration planning.

Cyanobacteria inoculation enhances carbon sequestration in soil substrates used in dryland restoration.

Despite significant efforts to restore dryland ecosystems worldwide, the rate of success of restoration is extremely low in these areas. The role of cyanobacteria from soil biocrusts in reestablishing soil functions of degraded land has been highlighted in recent years. These organisms are capable of improving soil structure and promoting soil N and C fixation. Nevertheless, their application to restore functions of reconstructed soils in dryland restoration programs is yet to be harnessed. In this study, we used microcosms under laboratory conditions to analyse the effects of inoculating soil substrates used in post-mine restoration with a mixture of N-fixing cyanobacteria isolated from soil biocrust (Nostoc commune, Tolypothrix distorta and Scytonema hyalinum) on i) the recovery of the biocrust, and ii) the carbon sequestration and mineralisation rates of these substrates. Soils were collected from an active mine site in the mining-intensive biodiverse Pilbara region (north-west Western Australia) and consisted of previously stockpiled topsoil, overburden waste material, a mixture of both substrates, and a natural soil from an undisturbed area. Our results showed that cyanobacteria rapidly colonised the mine substrates, with biocrust coverage ranging from 23.8 to 52.2% and chlorophyll a concentrations of up to 12.2 µg g-1 three months after inoculation. Notably, soil organic C contents increased 3-fold (P < 0.001) in the mine waste substrate (from 0.6 g kg-1 to 1.9 g kg-1) during this period of time. Overall, our results showed that cyanobacteria inoculation can rapidly modify properties of reconstructed soil substrates, underpinning the potential key role of these organisms as bio-tools to initiate recovery of soil functions in infertile, reconstructed soil substrates.

Estrogen receptor gene expression in human uterine leiomyomata.

Estrogen and progestin are believed to be important physiological regulators of uterine leiomyoma growth. We recently showed that progesterone receptor messenger ribonucleic acid (mRNA) and protein levels are increased in human uterine leiomyomas compared with those in myometrial biopsy tissue obtained from the same patient. To further characterize the molecular mechanisms underlying abnormal growth of uterine leiomyomas, we analyzed biopsy samples of tumor and adjacent normal myometrium for estrogen receptor (ER) gene expression. Northern analysis indicated that ER mRNA levels were increased 1.4-to 12.6-fold in leiomyoma compared with myometrium in all patients examined (n = 11), whereas beta-actin mRNA was not different between the two groups. The size of the primary ER mRNA transcript was 6.2 kilobases in both leiomyoma and myometrium, indicating no gross mutation of the ER gene. An ER protein of 66 kilodaltons was detected by Western blot analysis, and quantitative immunoassay of ER revealed 9448 +/- 1955 fmol/mg DNA in leiomyoma compared to 2827 +/- 979 fmol/mg DNA in myometrial tissue. Scatchard analysis of 17 beta-estradiol binding to cell-free extracts revealed enhanced binding capacity (per mg DNA) in leiomyoma tissue (n = 6) of about 6-fold, whereas ER binding affinity was not substantially different between the leiomyoma and adjacent myometrial tissues. We propose that increased expression of progesterone receptor in leiomyoma is most likely a consequence of overexpression of functional ER that results in increased end-organ sensitivity to estradiol.

Progesterone receptor messenger ribonucleic acid and protein are overexpressed in human uterine leiomyomas.

OBJECTIVE: Our purpose was to identify molecular mechanisms underlying abnormal growth of uterine leiomyomas. STUDY DESIGN: Biopsy samples of tumor and adjacent "normal" myometrium from nine patients were analyzed for progesterone receptor gene expression and for proliferation-associated antigen Ki-67. RESULTS: Northern analysis indicated that progesterone receptor messenger ribonucleic acid levels were increased twofold to 15-fold in leiomyoma compared with adjacent myometrial biopsy tissue from all patients (n = 9), whereas beta-actin messenger ribonucleic acid was at similar levels in these samples. Quantitative immunoassay, immunohistochemistry studies, and Western blot analyses revealed increased amounts of progesterone receptor protein in the tumor tissue. Both the progesterone receptor A and B forms were expressed in the leiomyoma and adjacent myometrium. Corresponding to increased progesterone receptor gene expression, the proliferation-associated antigen Ki-67 was also significantly elevated in the leiomyoma tissue. CONCLUSION: These data provide the first evidence that progesterone receptor messenger ribonucleic acid is overexpressed in uterine leiomyomas, suggesting that amplified progesterone-mediated signaling is instrumental in the abnormal growth of these tumors.