Plant growth and secondary metabolism are commonly regulated by external cues such as light, temperature and water availability. In this study, the influences of low and high temperatures, dehydration, photoperiods, and different growing stages on the changes of steviol glycosides (SGs) contents and transcription levels of fifteen genes involved in SGs biosynthesis of Stevia rebaudiana Bertoni were examined using HPLC and RT-PCR. The observations showed that the transcript levels of all the fifteen genes were maximum under 25 °C treatment, and the transcription of SrDXS, SrDXR, SrMCT, SrCMK, SrMDS, SrHDS, SrHDR, SrIDI, SrGGDPS, SrCPPS1, SrUGT85C2 and SrUGT76G1 were restrained both in low temperature (15 °C) and high temperature (35 °C). Most genes in SGs biosynthesis pathway exhibited down-regulation in dehydration. To elucidate the effect of photoperiods, the plants were treated by different simulated photoperiods (8 L/16 D, 1 0L/14 D, 14 L/10 D and 16 L/8 D), but no significant transcription changes were observed. In the study of growing stages, there were evident changes of SGs contents, and the transcript levels of all the fifteen genes were minimal in fast growing period, and exhibited evident increase both in flower-bud appearing stage and flowering stage. The obtained results strongly suggest that the effect of environmental cues on steviol glycosides contents and transcription of corresponding biosynthetic genes in S. rebaudiana is significant. It is worth to study deeply. #Stevia#kombucha#ikombucha_ro#ikombucha https://pubmed.ncbi.nlm.nih.gov/25500454/
More than 60 naturally occurring steviol glycosides in the Stevia rebaudiana Bertoni plant share a similar molecular structure with an aglycone steviol backbone conjugated with β- and α-glycosidic bonds to different sugar moieties. These glycosides are naturally produced in different quantities within the stevia leaf. Certain minor glycosides with superior sensory attributes, such as Reb D and Reb M, are found less than 0.1% in traditional stevia leaves. New technologies can now produce better tasting steviol glycosides by using enzymatic conversion of stevioside and Reb A, which are abundant in stevia leaf. Several regulatory authorities recently evaluated steviol glycosides produced by enzymatic conversion of stevia leaf extract and approved them safe for human consumption. Steviol glycosides undergo microbial hydrolysis in the colon to generate steviol, which is absorbed and metabolized into steviol glucuronide, and excreted primarily via human's urine. Previous studies have shown the hydrolysis of highly purified individual steviol glycosides extracted from stevia leaf are converted to steviol in the presence of colonic microbiota of adults. Since colonic microbiota of children may be different from adults, this study investigates the metabolic fate in the colonic microbiota of adults and children of the minor steviol glycosides produced by extraction and enzymatic conversion of major steviol glycosides from stevia leaf. Several in vitro incubation tests were conducted in human fecal homogenates collected from adult and pediatric populations with steviol glycoside test samples comprised of a complex stevia leaf extract, a blend of minor glycosides isolated from stevia extract and two mixtures of steviol glycosides produced by enzymatic conversion of Reb A to larger molecules by attaching glucose units via β- or α-glycosidic bonds. Results from these studies clearly demonstrate steviol glycosides produced by extraction from stevia leaf, or enzymatic conversion of stevia leaf extract, share the same metabolic fate in the human gut microbiota from adults and children. Considering a common metabolite structure and a shared metabolic fate in all ages, safety data for individual steviol glycosides can be used to support safety of all steviol glycosides produced by extraction and enzymatic conversion of stevia leaf extract. #Stevia#kombucha#ikombucha_ro#ikombucha https://pubmed.ncbi.nlm.nih.gov/32745585/
Stevia rebaudiana Bertoni is a valuable plant whose products are increasingly used in medicine, pharmacy and the food industry. This necessitates the use of biotechnological approaches for its mass propagation. Establishing optimal conditions for in vitro cultivation is essential for obtaining high biomass and secondary metabolites production. A large number of articles considering the role of plant growth regulators and other additives in the culture medium in the growth and development of Stevia are available in the literature. However, there are no summarized data about the use of nanoparticles in Stevia tissue cultures. Therefore, this review also includes the research conducted so far on the effect of nanoparticles on Stevia micropropagation. Furthermore, the influence of different elicitors on secondary metabolite production and antioxidant activity of in vitro-cultivated Stevia plants have been discussed. By referring to the collected literature, we concluded that biotechnological approaches applied to S. rebaudiana cultivation might improve the agronomic traits of plants and steviol glycosides production. #Stevia#kombucha#ikombucha_ro#ikombucha https://pubmed.ncbi.nlm.nih.gov/36616282/
Recent research dives deep into the impact of autism on marital bonds. Over a 30-year span, parents of children with autism showcased a 36% divorce rate, with specific peak periods. Surprisingly, families of verbally adept autistic teenagers faced unique stressors, leading to higher divorce rates. The strength and resilience of these families remind us of the unique challenges they face.
Hi, I'm not quite sure if this vhdl code and testbench is correct for the given task. Can you take a look?
Design a one-hour kitchen timer. The device should have buttons/switches to start and stop the timer, as well as to set the desired time interval for the alarm. Realize the task using the software package Quartus or in GHDL, confirm the correctness of the project task by simulation.
This is VHDL code:
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity Kitchen_Timer is
port (
clk : in std_logic; -- Clock input
reset : in std_logic; -- Reset input
start : in std_logic; -- Start button input
stop : in std_logic; -- Stop button input
alarm : out std_logic -- Alarm output
);
end entity Kitchen_Timer;
-- Declare the architecture for the kitchen timer
architecture Behavioral of Kitchen_Timer is
signal count : integer range 0 to 3600 := 0; -- Counter for timer
signal alarming : std_logic := '0'; -- Signal to indicate alarming interval
signal alarm_en : std_logic := '0'; -- Signal to enable alarming interval
signal alarm_cnt : integer range 0 to 600 := 0; -- Counter for alarming interval
begin
-- Process to control the kitchen timer and alarming interval
process (clk, reset)
begin
if (reset = '1') then
count <= 0;
alarming <= '0';
alarm_en <= '0';
alarm_cnt <= 0;
elsif (rising_edge(clk)) then
if (stop = '1') then
count <= 0;
alarming <= '0';
alarm_en <= '0';
alarm_cnt <= 0;
elsif (start = '1' and count < 3600) then
count <= count + 1;
if (count = 3600) then
count <= 0;
alarming <= '0';
alarm_en <= '0';
alarm_cnt <= 0;
elsif (count > 0) then
alarm_en <= '1';
end if;
end if;
if (alarm_en = '1') then
if (alarm_cnt < 600) then
alarm_cnt <= alarm_cnt + 1;
else
alarm_cnt <= 0;
alarming <= '1';
end if;
end if;
end if;
end process;
-- Assign the alarm output
alarm <= alarming;
end architecture Behavioral; ```
This is Testbench:
```library ieee;
use ieee.std_logic_1164.all;
entity tb_Kitchen_Timer is
end tb_Kitchen_Timer;
architecture tb of tb_Kitchen_Timer is
component Kitchen_Timer
port (clk : in std_logic;
reset : in std_logic;
start : in std_logic;
stop : in std_logic;
alarm : out std_logic);
end component;
signal clk : std_logic;
signal reset : std_logic;
signal start : std_logic;
signal stop : std_logic;
signal alarm : std_logic;
constant TbPeriod : time := 1000 ns; -- EDIT Put right period here
signal TbClock : std_logic := '0';
signal TbSimEnded : std_logic := '0';
begin
dut : Kitchen_Timer
port map (clk => clk,
reset => reset,
start => start,
stop => stop,
alarm => alarm);
-- Clock generation
TbClock <= not TbClock after TbPeriod/2 when TbSimEnded /= '1' else '0';
-- EDIT: Check that clk is really your main clock signal
clk <= TbClock;
stimuli : process
begin
-- EDIT Adapt initialization as needed
start <= '0';
stop <= '0';
-- Reset generation
-- EDIT: Check that reset is really your reset signal
reset <= '1';
wait for 100 ns;
reset <= '0';
wait for 100 ns;
-- EDIT Add stimuli here
wait for 100 * TbPeriod;
-- Stop the clock and hence terminate the simulation
TbSimEnded <= '1';
wait;
end process;
end tb;
-- Configuration block below is required by some simulators. Usually no need to edit.
configuration cfg_tb_Kitchen_Timer of tb_Kitchen_Timer is
for tb
end for;
end cfg_tb_Kitchen_Timer;```
#science