Immunocytochemical identification of glandular kallikrein in the rat anterior pituitary

Climatic and soil factors explain the two-dimensional spectrum of global plant trait variation

Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land-climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential. The orthogonality of these two axes suggests they are differently influenced by environmental drivers. We find that these axes persist in a global dataset of 17 traits across more than 20,000 species. We find a dominant joint effect of climate and soil on trait variation. Additional independent climate effects are also observed across most traits, whereas independent soil effects are almost exclusively observed for economics traits. Variation in size traits correlates well with a latitudinal gradient related to water or energy limitation. In contrast, variation in economics traits is better explained by interactions of climate with soil fertility. These findings have the potential to improve our understanding of biodiversity patterns and our predictions of climate change impacts on biogeochemical cycles.

Cellular mechanisms of estrogen- and dopamine-induced control of glandular kallikrein in the anterior pituitary of the rat

Glandular kallikrein (GK, a trypsin-like serine protease) exhibits estrogen induction and dopamine repression in rat pituitary lactotrophs. Steroid induction may reflect primary actions to increase selectively the synthesis of specific proteins, or may be part of broad cellular responses secondary to steroid-induced phenotype transitions. This study examined the cellular mechanisms underlying estrogen and dopaminergic control of lactotroph GK using a quantified immunocytochemical approach. Pituitaries from ovariectomized rats exhibited little GK staining. Estradiol treatment for 10 days produced dose-dependent increases in pituitary mass, the percentage of lactotrophs (indicating lactotroph proliferation) and the percentage of GK-positive cells. Also, GK staining intensity was dependent upon estradiol dose, increasing 4-fold between 5 micrograms and 50 micrograms/48 h. Dopamine receptor blockade with haloperidol (2.5 mg/kg/24 h) elicited weak GK immunostaining in 46% of the lactotrophs in the absence of estradiol, and markedly potentiated GK staining intensity elicited with low but not high doses of estradiol. The results suggest that GK induction is a primary estrogen effect, and is not secondary to a phenotype transition: the induction is enhanced by estrogen-induced lactotroph proliferation. Dopaminergic systems strongly inhibit GK induction by low estradiol levels. This dopaminergic modulation may shift the induction of lactotroph GK to physiological events associated with high estradiol levels or low dopaminergic tone.