Chinese Journal of Nature

The first black hole image: An introduction to black hole

WU Qingwen

2019, 41(3): 157-167. doi:10.3969/j.issn.0253-9608.2019.03.001

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Einstein discovered the special relativity and general relativity at 1905 and 1915 respectively. The most fundamental prediction of the general relativity is the existence of black hole. Now, we believe that there is a supermassive black hole and possibly billion of stellar-mass black holes in each galaxy. It is still unclear whether the intermediate mass of black hole exist or not. There are many indirect evidences for the existence of black holes at different scales by measuring the effects of an object surrounding the black
holes. The international collaboration group for the event horizon telescope try to achieve the high resolution that can resolve the
horizon of the two nearby supermassive black holes (in Milky Way and M87 at the center of Virgo cluster) by adopting a technique
known as very-long-baseline interferometry. For about 10 days in April of 2017, the scientists observed the Sgr A* and M87 by networking eight telescopes around the globe. In April 10 of 2019, the group of the event horizon telescope announced the first photo of the black hole at the center of M87, which is the most direct evidence for the existence of the black hole. This results further support the theory of the general relativity. In last part, I also simply review the possible future Chinese projects that will focus on the black hole physics.

Circadian clock and photoperiodism

YUAN Li, XIE Qiguang, XU Xiaodong

2019, 41(3): 168-173. doi:10.3969/j.issn.0253-9608.2019.03.002

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Within this vast universe, the earth rotates on its axis, and also orbits around the sun, which creates rapid changes of day and night and the seasons of the year. For these reasons, the natural cues of light, temperature, humidity, nutrition and other environmental factors essential for individual survivals change periodically. The organisms have to adapt to the environment caused by the selective pressures to ensure their reproduction. Of all the fitness, the adaptation to light/dark cycles is most important. Creatures at different latitudes on the earth experience the rhythmicity of sunlight intensity, variable range of light quality and illumination length during the year, and they choose the suitable location to complete the growth, development and reproduction. Evolution has instated the timekeeping mechanism from circadian clock to confer organisms the ability to integrate and foresee the daily and seasonal changes in light exposure, and then improved survival rate by scheduling the physical and metabolic process at the most appropriate time. The studies concerned with the functional connection between biological clock and photoperiodism, and the more results shown that the circadian oscillators are involved in the regulation of plant’s or animal’s capacity to respond to the photoperiod.

Molecular basis of soybean adaptation to long days and short days

LIN Xiaoya, LIU Baohui, KONG Fanjiang

2019, 41(3): 174-182. doi:10.3969/j.issn.0253-9608.2019.03.003

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The photoperiod is an important factor in regulating flowering time. In soybean, photoperiod regulation of flowering is one of the important factors affecting maturity and yields, and thus has attracted attentions of many agronomists. Soybeans have a wide adaptability, which is inseparable from the adaptability of different soybean cultivars to different photoperiods. The adaptation
of soybean to the photoperiod is controlled by a series of maturity genes. Under long days, soybeans need to reduce sensitivity to
photoperiod. Whereas, under short days, soybeans need to flower late to get high yields. In recent years, many maturity genes have been identified through forward genetics. Scientists have further analyzed the functions of these genes through genetics, molecular biology and biochemistry technology to get a clue of how the photoperiod regulate soybean flowering. This article summarizes the molecular identification of maturity genes and how they regulate flowering time under both long-day and short-day conditions.

Plant light signal transduction system

LI Xiukun, XU Dongqing

2019, 41(3): 183-187. doi:10.3969/j.issn.0253-9608.2019.03.004

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Light is one of the most essential environmental factors affecting plant development and growth. Throughout the entire life cycle of plants, light mediates almost every stage of developmental processes. Plants have evolved a complicated but delicate light signal transduction network in response to dynamically changing light environment in nature. Over the past three decades, plant photobiologists have revealed a light signal transduction system, photoreceptors-E3 ubiquitin ligase complex-transcription factors. This regulatory network affects approximately one third of gene expressions throughout whole genome to ensure normal development in plants.

Research progress in phytochrome A signaling

ZHOU Yangyang, LI Jigang

2019, 41(3): 188-196. doi:10.3969/j.issn.0253-9608.2019.03.005

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Phytochromes are red (R) and far-red (FR) light photoreceptors in plants, and phytochrome A (phyA) is the only plant photoreceptor that perceives FR light and then mediates various responses to this signal. The phyA is synthesized in the cytosol in the inactive Pr form; upon light illumination, phyA is converted to the biologically active Pfr form, and interact directly with the shuttle proteins FHY1 and FHL. The phyA is then imported into the nucleus by FHY1/FHL, while the phyA-FHY1/FHL complexes dissociate in the nucleus and FHY1/FHL return to the cytosol for the next phyA transportation cycle. A recently developed mathematical model suggested that the photoconversion of phyA between Pr and Pfr forms and FHY1/FHL-dependent nuclear trafficking cycles determine phyA’s response profile to far-red light. In the nucleus, phyA interacts with COP1 and SPA proteins directly, leading to the disruption and inactivation of the COP1/SPA complexes and the accumulation of HY5, a bZIP family transcription factor acting as a key positive regulator of photomorphogenesis. The Pfr form of phyA also interacts directly with the PIF proteins, a group of bHLH family transcription factors acting as repressors of photomorphogenesis, and induces rapid phosphorylation and degradation of PIFs. FHY3 and FAR1 are transposase-derived transcription factors which directly activate the transcription of FHY1 and FHL under farred light; however, HY5 negatively regulates FHY3/FAR1-activated FHY1/FHL expression, thus playing a role in fine-tuning phyA signaling homeostasis. The Pfr form of phyA could be phosphorylated in the nucleus, and the phosphorylated phyA form may serve as the preferred substrate for the COP1/SPA complex-mediated degradation. It was recently shown that the phosphorylated phyA form may represent a moreactive form of phyA, thus playing an essential role in inducing the FR light response.

Optogenetics: A new technology to control behavior using light

GUO Xiaoqiang

2019, 41(3): 197-206. doi:10.3969/j.issn.0253-9608.2019.03.006

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Light can be sensitized by organisms from lower bacteria and algae to higher animals including as humans through rhodopsin system. Since the 1970s, identification of several channelrhodopsins in bacteria and algae laid the foundation for lightcontrolled
operation. Optogenetics, initiated by Gero Miesenböck in 2002 and further developed by Karl Deisseroth and Edward Boyden in 2005, has greatly enhanced our understanding of brain function. Optogenetics allows scientists to switch on or off specificn eurons in the brain using light and manipulate the activity of neurons and animal’s behavior. Optogenetics was proven to be a highly powerful and useful tool for studying healthy and pathological brain activity from a cellular and system level. In the article, there are systematically introduced including the historical background, major events, development process, application fields and important values of optogenetics.

Ternary optical computer

JIN Yi, WANG Zhehe, LIU Yujing, OUYANG Shan, SHEN Yunfu, PENG Junjie

2019, 41(3): 207-218. doi:10.3969/j.issn.0253-9608.2019.03.007

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The ternary optical computer is a general purpose photoelectric hybrid computer system which was set in March 2017. It uses dark state and two polarized light states which be orthogonal polarization direction to express information, and uses liquid crystal and polarizer to change these three light states, and then completes the three-valued logical operation and the binary parallel addition operation of redundant MSD to express numerical values. This new computer has many advantages, such as large number of processor bits, independent use of processor bits in groups, and reconfigurable computing functions of processor bits. On the basis of non-volatile random storage device, a dual-space memory system is constructed which frequently exchanges a large amount of data with the processor. For ease of writing applications with these characteristics, SZG files are adopted to shield the difference between ternary optical processors and traditional electronic processors for programmers. Meanwhile, the SZG file and program language form a new programming platform which will maintain the traditional programming technology. At present, for the typical algorithms such as fast Fourier transform and cellular automata, the acceleration ability of this new computer is verified.

Black hole marks a new era of muti-messenger astronomy

LI Cong

2019, 41(3): 219-223. doi:10.3969/j.issn.0253-9608.2019.03.008

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Black hole is the most mysterious object in the universe, which has only existed in the theoretical hypothesis for a long time. However, with the development of modern astronomy, we have got many evidences for existence of black hole. Especially with
the development of gravitational wave and neutrino detection, we can not only get information from black hole via electromagnetic
radiation but other “messengers”, which marks a new era of muti-messenger astronomy!

Global cooperation advances human knowledge#br#

GUAN Yi

2019, 41(3): 224-230. doi:10.3969/j.issn.0253-9608.2019.03.009

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In memory of Winslow Briggs, a luminary who shed light on plants and enlightened people#br#

DENG Xingwang

2019, 41(3): 231-234. doi:10.3969/j.issn.0253-9608.2019.03.010

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Winslow Briggs , an accomplished and highly respected scientist in plant biology, carrying out his beloved research and experiments until the very end of his life. He discovered the blue light photoreceptor phototropins. Winslow is an inspirational mentor and role model who has impacted multiple generations of scientists. He was also an enthusiastic proponent of biological research to the public. He will be remembered by the generations to come.

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