The steroid hormone 20-hydroxyecdysone (20E) initiates insect molting and
metamorphosis through binding with a heterodimer of two nuclear recep-tors, the ecdysone receptor (EcR) and ultraspiracle (USP). Expression of
the specific isoforms EcR-A and EcR-B1 governs steroid-induced responses
in the developing cells of the silkworm Bombyx mori.
1. Sau khi tìm hiểu các trang web ở trên hãy giải thích thế nào là genome browser ?
2. Mục đích của genome browser ?
3. Cho biết có bao nhiêu genome đã được xác định trình tự ở các genome browser ?
4. Sử dụng UCSC genome browser, hãy cho biết ý nghĩa của :
Bài báo cáo tập trung nghiên cứu các chuẩn về y khoa như HL7, DICOM để đưa ra giải pháp xây dựng bệnh án điện tử (ECR - Electronic Clinical Record) phục vụ cho việc chẩn đoán y khoa. Từ đó có tác dụng hỗ trợ nghiên cứu lâm sàng, dịch tễ, chất lượng chǎm sóc sức khoẻ, tác dụng của thuốc.
The results showed that weight gain (WG), showed that fishmeal protein replacement levels had significant effects on fish weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), economic conversion ratio (ECR) (P 50 % protein (Công ty EWOS) trong đó bột cá được xem là nguồn protein chủ yếu trong thức ăn. Tuy nhiên trong những năm gần đây, sản lượng bột cá đang giảm dần và giá thành ngày một tăng.
In plants, regulation of transgene expression is typically accomplished
through the use of inducible promoter systems. The ecdysone receptor
(EcR) gene switch is one of the best inducible systems available to regulate
transgene expression in plants.
Regulated expression of transgene is essential in basic research as well as
for many therapeutic applications. The main purpose of the present study
is to understand the functioning of the ecdysone receptor (EcR)-based gene
switch in mammalian cells and to develop improved versions of EcR gene
A pair of nuclear receptors, ecdysone receptor (EcR) and ultraspiracle
(USP), heterodimerize and transduce ecdysteroid signals. The EcR and its
nonsteroidal ligands are being developed for regulation of transgene expres-sion in humans, animals and plants. In mammalian cells, EcR:USP
heterodimers can function in the absence of ligand, but EcR⁄retinoid X
receptor (EcR:RXR) heterodimers require the presence of ligand for activa-tion.
The IAL-PID2 cells derived from imaginal wing discs of the
last larval instar of Plodia interpunctellawere responsive to
20-hydroxyecdysone (20E). These imaginal cells respond to
20E by proliferative arrest followed by a morphological
differentiation. These 20E-induced late responses were
inhibited in presence of juvenile hormone (JH II). From
these imaginal wing cells, we have cloned a cDNA sequence
encoding aP. interpunctellaecdysone receptor-B1 isoform
Nongenomic action of an insect steroid hormone, 20-hy-droxyecdysone (20E), has been implicated in several 20E-dependent events including the programmed cell death of
Bombyxanterior silk glands (ASGs), but no information is
available for themodeof theaction.Weprovide evidence for
a putative membrane receptor located in the plasma mem-brane of the ASGs. Membrane fractions prepared from the
ASGs exhibit high binding activity to [
cDNA cloning of ecdysone receptor (EcR) and ultraspiracle (USP) of the
coleopteran Colorado potato beetleLeptinotarsa decemlineata(LdEcR and
LdUSP) was conducted. Amino-acid sequences of the proteins deduced
from cDNA sequences showed striking homology to those of other insects,
especially the coleopteran yellow mealworm Tenebrio molitor.
Gene switches have potential applications for the regulation of transgene
expression in plants and animals. Recently, we have developed a two-hybrid ecdysone receptor (EcR) gene switch using chimera 9 [CH9, a chi-mera between helices 1–8 ofHomo sapiensretinoid X receptor (HsRXR)
and helices 9–12 ofLocusta migratoriaRXR (LmRXR)] as a partner for
Choristoneura fumiferanaEcR (CfEcR).
Insect development is driven by the action of ecdysteroids on morphogenetic
processes. The classic ecdysteroid receptor is a protein heterodimer com-posed of two nuclear receptors, the ecdysone receptor (EcR) and Ultraspira-cle (USP), the insect ortholog of retinoid X receptor. The functional
properties of EcR and USP vary among insect species, and provide a basis
for identifying novel and species-specific insecticidal candidates that disrupt
this receptor’s normal activity.
A set of thirty-two natural and ten semisynthetic ecdysteroids was assayed
in murine 3T3 cells across ten different ecdysteroid receptor (EcR) ligand-binding domains derived from nine arthropod species in an engineered gene
switch format. Among the ecdysteroids tested, the most biologically wide-spread ecdysteroid, 20-hydroxyecdysone (20E), was moderately and consis-tently potent across the tested EcRs.
To develop an ecdysone receptor (EcR)-based inducible
gene regulation system, several constructs were prepared by
fusing DEF domains of Choristoneura fumiferanaEcR
(CfEcR),C. fumiferanaultraspiracle (CfUSP),Mus muscu-lus retinoid X receptor (MmRXR) to either GAL4 DNA
binding domain (DBD) or VP16 activation domain. These
constructs were tested in mammalian cells to evaluate their
ability to transactivate luciferase gene placed under the
control of GAL4 response elements and synthetic TATAA
The insect ecdysteroid receptor consists of a heterodimer between EcR and the RXR-orthologue, USP. We addressed the question of whether this heterodimer, like all other RXR heterodimers, may be formed in the absence of ligand and whether ligand promotes dimerization. We found that C-terminal protein fragments that comprised the ligand binding, but not the DNA binding domain of EcR and USP and which were equipped with the activation or DNA binding region of GAL4, respectively, exhibit a weak ability to interact spontaneously with each other.