Morpho-Histology, Endogenous Hormone Dynamics and Transcriptome Profiling in Dacrydium Pectinatum during Male Cone Development

Dacrydium pectinatum de Laubenfels is a perennial gymnosperm species dominant in tropical montane rain forests. Due to severe damages by excessive deforestation, typhoons, and other external forces, the population of the species has been significantly reduced. Furthermore, its natural regeneration is poor. To better understand the male cone development in D. pectinatum, we examined the morphological and anatomical changes, analyzed the endogenous hormone dynamics, and profiled gene expression. The morpho-histological observations suggest that the development of D. pectinatum male cone can be largely divided into four stages: microspore primordium formation (April to May), microspore sac and pollen mother cell formation (July to November), pollen mother cell division (January), and pollen grain formation (February). The levels of gibberellins (GA), auxin (IAA), abscisic Acid (ABA), cytokinin (CTK), and jasmonic acid (JA) fluctuated during the process of male cone development. The first transcriptome database for a Dacrydium species was generated, revealing >70,000 unigene sequences. Differential expression analyses revealed several floral and hormone biosynthesis and signal transduction genes that could be critical for male cone development. Our study provides new insights on the cone development in D. pectinatum and the foundation for male cone induction with hormones and studies of factors contributing to the species’ low rate of seed germination.

Lipoprotein(a) levels are not independently associated with endogenous steroid hormone levels, in contrast to other non-genetic and genetic factors: the population-based SKIPOGH study

Introduction Lipoprotein(a) [Lp(a)] is an LDL-like molecule that is likely causally related to cardiovascular events. Lp(a) levels are highly variable, by more two orders of magnitude, and most of this variability appears to be of genetic origin. Exogenous hormones (hormone replacement therapy) seem to influence Lp(a) levels, but the impact of the variation of endogenous hormone levels on Lp(a) is unknown. Purpose To investigate the association between Lp(a) levels and non-genetic factors, as endogenous steroid hormone levels, in contrast to genetic factors. Methods We investigated the association of 28 endogenous steroids with Lp(a) levels and compared the association to other non-genetic and genetic variables in a prospective, population-based sample (N=1,021). Results The average age of the participants was 51 years and 53% were female. Median Lp(a) levels were 62 (±204) mg/l and the 90th and 99th percentile of Lp(a) was 616mg/l and 1035 mg/l respectively. The prevalence of a Lp(a) elevation ≥700mg/l was 3.2% and Lp(a) varied greatly from undetectable to 1,690mg/l. Age explained 2.0% of Lp(a) variability (p<0.001), 1% was explained by LDL levels (p=0.001), and 40% by two single nucleotide polymorphisms near the Lp(a) gene that have been previously described. Lp(a) levels were on average almost two times more elevated in secondary prevention and in individuals with very elevated LDL levels (≥4.9 mmol/l). Of the 28 endogenous steroid hormones assessed, 5-androstene-3b,16α,17β-triol, androsterone, 16α-hydroxy DHEA, and estriol were nominatively associated with serum Lp(a) levels and explained 0.4–1% of Lp(a) variability in univariate analyses, but they did not reach significance in multi-variate models. Conclusion Our results confirm previous findings demonstrating that the majority of the Lp(a) variation in the general population is of genetic origin. Age and LDL-levels explain a further small part of Lp(a) variability. Endogenous hormone levels do not contribute significantly to the wide range of variability. FUNDunding Acknowledgement Type of funding sources: None. Coefficient plot Lp(a) and variables

ETB receptor-mediated vasodilation is regulated by estradiol in young women

The endothelin-B (ETB) receptor mediates vasodilation in young women, an effect lost following menopause. It is unclear whether these alterations are due to aging or changes in estradiol (E2). During endogenous hormone suppression (GnRH antagonist), blockade of ETB receptors enhanced cutaneous microvascular vasodilation. However, during E2 administration, blockade of ETB receptors attenuated vasodilation, indicating that the ETB receptor mediates dilation in the presence of E2. In young women, ETB receptors mediate vasodilation in the presence of E2, an effect that is lost when E2 is suppressed.

Physiological and transcriptome analyses for assessing the effects of exogenous uniconazole on drought tolerance in hemp (Cannabis sativa L.)

Uniconazole (S-(+)-uniconazole), a plant growth retardant, exerts key roles in modulating growth and development and increasing abiotic stress tolerance in plants. However, the underlying mechanisms by which uniconazole regulates drought response remain largely unknown. Here, the effects of exogenous uniconazole on drought tolerance in hemp were studied via physiological and transcriptome analyses of the drought-sensitive industrial hemp cultivar Hanma No. 2 grown under drought stress. Exogenous uniconazole treatment increased hemp tolerance to drought-induced damage by enhancing chlorophyll content and photosynthesis capacity, regulating activities of enzymes involved in carbon and nitrogen metabolism, and altering endogenous hormone levels. Expression of genes associated with porphyrin and chlorophyll metabolism, photosynthesis-antenna proteins, photosynthesis, starch and sucrose metabolism, nitrogen metabolism, and plant hormone signal transduction were significantly regulated by uniconazole compared with that by control (distilled water) under drought stress. Numerous genes were differentially expressed to increase chlorophyll content, enhance photosynthesis, regulate carbon–nitrogen metabolism-related enzyme activities, and alter endogenous hormone levels. Thus, uniconazole regulated physiological and molecular characteristics of photosynthesis, carbon–nitrogen metabolism, and plant hormone signal transduction to enhance drought resistance in industrial hemp.