5 research outputs found
Improved Search for νμ→νe Oscillation in a Long-Baseline Accelerator Experiment
journal articl
Molecular form identification of anterior pituitary gland-secreted prolactin in chicken
Endocrine changes during bird reproduction are well documented. Prolactin (PRL) exhibits a strong relationship between incubation and broody behavior. The molecular forms of PRL in the anterior pituitary gland during the reproductive cycle have already been previously identified but not those in the secreted form. To identify the molecular forms of secreted PRL during the reproductive cycle, we thus monitored the physiological status and incubation behavior of 10 Silkie hens by a video recording system over 1–2 years. Nine out of ten mature hens exhibited incubation behavior multiple times during the experiment. Ten hens demonstrated two interesting features. In a typical clutch, hens spent 10–15 min in the nest to lay an egg. Once they spent over 1 h in the nest, the nest occupancy increased incrementally. This shift in the nest occupancy occurred 7–10 days before the incubation onset and was highly repeatable. Based on the behavior of the hens, we cultured the anterior pituitary gland during four stages (premature non-laying, laying, trans, and incubation) with physiological PRL-releasing factor, vasoactive intestinal peptide (VIP). Based on our two-dimensional protein analysis, glycosylated PRL (G-PRL) displayed several isoforms with varying isoelectric points (pI), whereas we could detect one primary signal for non-glycosylated PRL (NG-PRL). However, 3–4 NG-PRL isoforms were detected in the anterior pituitary gland. These results suggested that secreted PRL, especially from the trans and incubation stages, contains various isoforms and it is post-translationally glycosylated and phosphorylated.journal articl
Cytokinins Control Endocycle Onset by Promoting the Expression of an APC/C Activator in Arabidopsis Roots
Plant roots respond to various internal and external signals and adjust themselves to changes of environmental conditions. In the root meristem, stem cells produce daughter cells that continue to divide several times. When these latter cells reach the transition zone, they stop dividing and enter the endocycle, a modified cell cycle in which DNA replication is repeated without mitosis or cytokinesis. The resultant DNA polyploidization, named endoreduplication, is usually associated with an increase of nuclear and cell volume and with cell differentiation [1,2,3,4]. At the transition zone, cytokinin signaling activates two transcription factors, type-B ARABIDOPSIS RESPONSE REGULATOR 1 (ARR1) and ARR12, and induces SHY2/IAA3, a member of the Aux/IAA family of auxin signaling repressors. This inhibits auxin signaling and reduces the expression of auxin efflux carriers, resulting in cell division arrest [5]. Such counteracting actions of two hormones are assumed to determine meristem size. However, it remains unknown whether cytokinins additionally control meristem size through an auxin-independent pathway. Here we show that, in Arabidopsis, the cytokinin-activated ARR2 directly upregulates the expression of CCS52A1, which encodes an activator of an E3 ubiquitin ligase, anaphase-promoting complex/cyclosome (APC/C) [6], thereby promoting the onset of the endocycle and restricting meristem size. Our genetic data revealed that CCS52A1 function is independent of SHY2-mediated control of auxin signaling, indicating that downregulation of auxin signaling and APC/C-mediated degradation of cell-cycle regulators cooperatively promote endocycle onset, and thus fine tune root growth.journal articl
