Screens in fly and beetle reveal vastly divergent gene sets required for developmental processes.

BACKGROUND: Most of the known genes required for developmental processes have been identified by genetic screens in a few well-studied model organisms, which have been considered representative of related species, and informative-to some degree-for human biology. The fruit fly Drosophila melanogaster is a prime model for insect genetics, and while conservation of many gene functions has been observed among bilaterian animals, a plethora of data show evolutionary divergence of gene function among more closely-related groups, such as within the insects. A quantification of conservation versus divergence of gene functions has been missing, without which it is unclear how representative data from model systems actually are. RESULTS: Here, we systematically compare the gene sets required for a number of homologous but divergent developmental processes between fly and beetle in order to quantify the difference of the gene sets. To that end, we expanded our RNAi screen in the red flour beetle Tribolium castaneum to cover more than half of the protein-coding genes. Then we compared the gene sets required for four different developmental processes between beetle and fly. We found that around 50% of the gene functions were identified in the screens of both species while for the rest, phenotypes were revealed only in fly (~ 10%) or beetle (~ 40%) reflecting both technical and biological differences. Accordingly, we were able to annotate novel developmental GO terms for 96 genes studied in this work. With this work, we publish the final dataset for the pupal injection screen of the iBeetle screen reaching a coverage of 87% (13,020 genes). CONCLUSIONS: We conclude that the gene sets required for a homologous process diverge more than widely believed. Hence, the insights gained in flies may be less representative for insects or protostomes than previously thought, and work in complementary model systems is required to gain a comprehensive picture. The RNAi screening resources developed in this project, the expanding transgenic toolkit, and our large-scale functional data make T. castaneum an excellent model system in that endeavor.

Insights into the Interaction of Lysosomal Amino Acid Transporters SLC38A9 and SLC36A1 Involved in mTORC1 Signaling in C2C12 Cells.

Amino acids are critical for mammalian target of rapamycin complex 1 (mTORC1) activation on the lysosomal surface. Amino acid transporters SLC38A9 and SLC36A1 are the members of the lysosomal amino acid sensing machinery that activates mTORC1. The current study aims to clarify the interaction of SLC38A9 and SLC36A1. Here, we discovered that leucine increased expressions of SLC38A9 and SLC36A1, leading to mTORC1 activation. SLC38A9 interacted with SLC36A1 and they enhanced each other's expression levels and locations on the lysosomal surface. Additionally, the interacting proteins of SLC38A9 in C2C12 cells were identified to participate in amino acid sensing mechanism, mTORC1 signaling pathway, and protein synthesis, which provided a resource for future investigations of skeletal muscle mass.

Identification of amino acid response element of SLC38A9 as an ATF4-binding site in porcine skeletal muscle cells.

Amino acids can affect protein synthesis by activating mammalian target of rapamycin complex 1 (mTORC1) signaling pathway. Amino acid transporters SLC38A9 on the lysosomal membrane not only transport amino acids, but also can sense amino acids and activate mTORC1 signaling pathway. Activating transcription factor 4 (ATF4) can promote the expression of amino acid transporters by binding with amino acid response element (AARE). In this study, two AAREs were found in the SLC38A9 promoter region of pig, and both of them bound to ATF4. The AARE in the first intron was located in the core promoter region of SLC38A9. ATF4 regulated mRNA expression level of SLC38A9 in porcine skeletal muscle cells. In the absence of amino acids, the expression of ATF4 decreased and the expression of SLC38A9 increased. After leucine addition, the expression levels of ATF4 and SLC38A9 increased. It suggested that in the absence of amino acids, the expression of SLC38A9 was increased via binding of ATF4 to AARE binding factors in SLC38A9 promoter fragment; after the addition of leucine, ATF4 was activated, resulting in the increase of SLC38A9 expression.

The effects of reduced dietary protein level on amino acid transporters and mTOR signaling pathway in pigs.

Amino acid transporter plays an important role in regulating mTOR signaling pathway. This study investigated the effects of reduced dietary protein levels on amino acid transporters and mTOR signaling pathway. A total of 54 weaning pigs were randomly allocated into a 3 × 3 factorial design, followed by slaughtering the pigs separately after 10-, 25- and 45-day feeding, with 18 pigs from each feeding period divided into three subgroups for treatment with three different protein-level diets: 20% crude protein (CP) diet (normal recommended, high protein, HP), 17% CP diet (medium protein, MP) and 14% CP diet (low protein, LP). The results indicated that reduced dietary protein level decreased the weight of longissimus dorsi. Additionally, quantitative PCR chip analysis showed that mRNA expression of amino acid transporters SLC38A2, SLC1A7, SLC7A1, SLC7A5, SLC16A10 and SLC3A2 in the LP group were significantly (P < 0.05) higher than those in the MP or HP group, and the phosphorylation of mTOR and S6K1 decreased in the LP group after 25-day feeding. Furthermore, the vitro experimental results further confirmed that the mRNA levels for SLC7A1, SLC7A5, SLC3A2, SLC38A2 and SLC36A1 were increased and the phosphorylation of mTOR and S6K1 was decreased when the concentration of amino acids in C2C12 myoblasts was reduced. All these results indicated that the LP diet induced a high expression of amino acid transporters and the inhibition of the mTOR activity, which resulting in restriction on protein synthesis and longissimus dorsi growth.

Elucidating a molecular mechanism that the deterioration of porcine meat quality responds to increased cortisol based on transcriptome sequencing.

Stress response is tightly linked to meat quality. The current understanding of the intrinsic mechanism of meat deterioration under stress is limited. Here, male piglets were randomly assigned to cortisol and control groups. Our results showed that when serum cortisol level was significantly increased, the meat color at 1 h postmortem, muscle bundle ratio, apoptosis rate, and gene expression levels of calcium channel and cell apoptosis including SERCA1, IP3R1, BAX, Bcl-2, and Caspase-3, were notably increased. However, the value of drip loss at 24 h postmortem and serum CK were significantly decreased. Additionally, a large number of differentially expressed genes (DEGs) in GC regulation mechanism were screened out using transcriptome sequencing technology. A total of 223 DEGs were found, including 80 up-regulated genes and 143 down-regulated genes. A total of 204 genes were enriched in GO terms, and 140 genes annotated into in KEGG database. Numerous genes were primarily involved in defense, inflammatory and wound responses. This study not only identifies important genes and signalling pathways that may affect the meat quality but also offers a reference for breeding and feeding management to provide consumers with better quality pork products.

Characteristics of the temperature-tunable Nd:YAG/YVO4 Raman laser.

We demonstrate a tunable crystalline Raman laser by varying the temperature of Raman crystal. Nd:YAG and YVO(4) crystals were selected as the laser and Raman gain media, respectively. The center wavelength of this Nd:YAG/YVO(4) Raman laser was tuned over a 0.49 nm range from 1175.76 to 1175.27 nm when the temperature of the Raman crystal was adjusted from 5 °C to 150 °C. The characteristics of this Raman laser including tunability, output power, and beam quality factors (M(2)) dependent on temperature were also studied in this paper.

Theoretical and experimental studies on output characteristics of an intracavity KTA OPO.

An acousto-optically Q-switched Nd:YVO(4)/KTiOAsO(4) (KTA) intracavity optical parametric oscillator (OPO) is efficiently realized in singly resonated scheme. With an end-pumping diode power of 25.9 W, output signal (1535 nm) power of 3.77 W and idler power (3467 nm) of 1.18 W are obtained at a pulse repetition rate of 50 kHz. A rate-equation model is set up to simulate the output power and time characteristics of both signal and idler waves. And both the numerical and experimental results show that the idler pulse width is shorter than the signal one in a singly resonant OPO.

Efficient 1.8 µm KTiOPO4 optical parametric oscillator pumped within an Nd:YAG/SrWO4 Raman laser.

A 1.8 µm optical parametric oscillator (OPO) based on a noncritically phase-matched KTiOPO4 crystal is demonstrated. OPO and stimulated Raman scattering techniques are successfully combined in an acousto-optically Q-switched Nd:YAG/SrWO4 Raman laser. The device efficiently realizes three steps of conversion: from a laser diode wavelength of 808 nm to the fundamental wavelength of 1064 nm; next, to the Stokes wavelength of 1180 nm; and finally to the OPO signal wavelength of 1810 nm. With an incident diode power of 7.2 W and a pulse repetition rate of 15 kHz, an average signal power of 485 mW is obtained with a diode-to-signal conversion efficiency of 6.75%. The beam quality factors (M2) of the signal wave in both horizontal and vertical directions are measured to be 1.7±0.2. The numerical output power results of the system, the thermal lensing, and the stability parameter of the cavity are also discussed.