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Bivoltine silkworms (Bombyx mori) are destined to respectively produce diapause or non-diapause eggs when they are reared under short or long days during the larval stage. The insulin signaling pathway is thought to play an essential role in regulating diapause in various insect species, but its involvement in silkworm diapause programming has not been investigated in detail. Therefore, we examined day-night expression of the insulin receptor (InR) gene in the silkworm larval brain under different photoperiods or in night interruption experiments in which larvae were exposed to light for 2 h during the nighttime of short days. Expression of the InR gene was photoperiod-dependent and InR mRNA levels decreased with increasing daylength. As the daylength increased, expression during the nighttime decreased to lower stable levels earlier than that during the daytime. During night interruptions that induced non-diapause, the nighttime expression of InR decreased to low levels like those during long days, although daytime expression was only moderately decreased. Nighttime InR expression was downregulated in silkworms reared under non-diapause-inducing conditions (long days and night interruptions). In contrast, abundant InR was expressed during the day and night in short days that induced diapause. Our findings suggested that InR expression in the larval brain is associated with programming the diapause status in the next generation of silkworms. Downregulated InR might suppress the insulin signaling pathway and cause non-diapause induction in the next generation. DOI: http://dx.doi.org/10.5281/zenodo.10413155

Rab, a low molecular weight GTP-binding protein, regulates the transmission of intracellular proteins. Insect neuropeptides that are directly involved in growth, development, reproduction, homeostasis, courtship, feeding, circadian rhythm and many other physiological processes are synthesized in neurons and ganglia in the brain and secreted by specific neurosecretory cells in tissues such as the corpus allatum and frontal ganglion. To clarify the relationship between Rabs, two neuropeptides, Allatotropin (AT) and Prothoracicotropic hormone (PTTH) and the circadian clock protein, Period (PER), were used to determine the locations of nine Rabs (Rab1, Rab3, Rab6, Rab7, Rab11, Rab14, Rab19, Rab21 and RabX4). Rab6-, Rab11-, Rab14- and Rab21-immunohistochemical reactivities (IRs) partially overlapped AT-IR in the brain in B. mori. Rab3-, Rab6-, Rab11-, Rab14-, and Rab21-IRs overlapped AT-IR in the frontal ganglion. Of the seven Rabs, only Rab11-IR overlapped PTTH-IR in the brain. Rab1-, Rab3-, Rab11-, Rab14-, Rab19-, Rab21-, RabX4- and NUF (nuclear fallout, an effector of Rab11)-IRs, overlapped PER-IR in the brain. Therefore, Rab may regulate the exocytosis of PTTH, AT and a protein associated with the circadian rhythm.

Maternal silkworms (Bombyx mori) of bivoltine strains are destined to produce either diapause or non-diapause eggs depending on environmental factors, such as, temperature and photoperiod experienced during the egg and larval stages. However, the molecular mechanisms that program diapause, which depend on information about the environment, remain unclear. We aimed to identify genes that are involved in programming diapause in the next generation in bivoltine silkworms. We therefore screened differentially expressed genes (DEGs) in the larval brains of diapause- and non-diapause-egg producers kept under three different diapause-inducing conditions using cap analysis of gene expression. Under each condition, only temperature, illumination or photoperiod was changed during the egg or larval stage as a diapause-controlling stimulus to induce the production of diapause or non-diapause eggs. We then verified the expression of DEGs that were common to all the three conditions using real-time quantitative PCR. We investigated the functional involvement of candidate genes in programming diapause using double-stranded RNA interference (RNAi) for gene knockdown. The results showed more abundant juvenile hormone acid methyltransferase (Jhamt) and proton-coupled folate transporter (Pcft) gene expression in the brains of fifth instar larvae of producers of diapause eggs than those of non-diapause eggs under the three conditions. Furthermore, RNAi against either of these genes significantly decreased the incidence of diapause in the next generation. These findings indicate that both Jhamt and Pcft are involved in the programming of diapause in the silkworm brain. These genes could function in retaining information that leads to diapause in the next generation.

Rab proteins are small GTP-binding proteins and are the largest family in the Ras GTPase superfamily and mediate vesicular transport in cells. Diverse insulin-like peptides, such as bombyxin, are synthesized in the brain and secreted into the haemolymph by the corpus allatum (CA). In the brain of Bombyx mori, Rabs are expressed in a specific area; however, which Rabs actually link the secretion of bombyxin remains unknown. A double-staining analysis of nine Rabs (Rab1, 3, 6, 7, 14, 21, 26, 39 and X4) and bombyxin indicated that Rab3-, Rab7-, Rab39- and RabX4-immunohistochemical reactivity (ir) areas overlapped with bombyxin-ir in the brain and CA in B. mori, while Rab6-, Rab14- and Rab21-irs partially overlapped in the CA. Rab1-ir occurred in the other immunopositive areas in CA. Rab26-ir did not occur in the brain. Rab39-ir occurred in UNC104, Rab39- effector, -immunopositive neurons in the brain and CA. Thus, Rab3, 7, 39 and X4 may regulate the exocytosis of bombyxin.

The present study investigated the ability of silkworm Bombyx mori (Lepidoptera: Bombycidae) larvae to learn. Silkworm larvae were trained to consume food that was placed on red paper; consequently they became attracted to red, rather than blue paper even in the absence of food. In contrast, untrained controls had no preference for either red or blue paper. These results suggested that silkworm larvae learned to associate red paper with food, and that they can discriminate colors. DOI: http://dx.doi.org/10.5281/zenodo.5609468

In patients with diabetes, albuminuria is a risk marker of end-stage renal disease and cardiovascular events. An increased renin-angiotensin system activity has been reported to play an important role in the pathological processes in these conditions. We compared the effect of aliskiren, a direct renin inhibitor (DRI), with that of angiotensin receptor blockers (ARBs) on albuminuria and urinary excretion of angiotensinogen, a marker of intrarenal renin-angiotensin system activity.We randomly assigned 237 type 2 diabetic patients with high-normal albuminuria (10 to

Lipid-derived reactive carbonyl species (RCS) possess electrophilic moieties and cause oxidative stress by reacting with cellular components. Arabidopsis (Arabidopsis thaliana) has a chloroplast-localized alkenal/one oxidoreductase (AtAOR) for the detoxification of lipid-derived RCS, especially α,β-unsaturated carbonyls. In this study, we aimed to evaluate the physiological importance of AtAOR and analyzed AtAOR (aor) mutants, including a transfer DNA knockout, aor (T-DNA), and RNA interference knockdown, aor (RNAi), lines. We found that both aor mutants showed smaller plant sizes than wild-type plants when they were grown under day/night cycle conditions. To elucidate the cause of the aor mutant phenotype, we analyzed the photosynthetic rate and the respiration rate by gas-exchange analysis. Subsequently, we found that both wild-type and aor (RNAi) plants showed similar CO2 assimilation rates; however, the respiration rate was lower in aor (RNAi) than in wild-type plants. Furthermore, we revealed that phosphoenolpyruvate carboxylase activity decreased and starch degradation during the night was suppressed in aor (RNAi). In contrast, the phenotype of aor (RNAi) was rescued when aor (RNAi) plants were grown under constant light conditions. These results indicate that the smaller plant sizes observed in aor mutants grown under day/night cycle conditions were attributable to the decrease in carbon utilization during the night. Here, we propose that the detoxification of lipid-derived RCS by AtAOR in chloroplasts contributes to the protection of dark respiration and supports plant growth during the night. [ABSTRACT FROM AUTHOR]

This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available. [ABSTRACT FROM AUTHOR]

The article offers information on scavenging systems for reactive carbonyls in the cyanobacterium Synechocystis. Topics discussed include sugar and lipid-derived reactive carbonyls (RCs) in the Synechocystis, aldo-keto reductase (AKR) reaction, medium-chain dehydrogenase/reductase (MDR) and short-chain dehydrogenase/reductase (SDR).

In this article, the author discusses a research related to the functional analysis of the aldo-keto reductase (AKR4C) subfamily of Arabidopsis thaliana. Topics discussed include trióse phosphate, methylglyoxal (MG), and plant diabetes. Other topics discussed include sugar metabolism in organisms involves the danger of suffering from cell damage due to sugar toxicity, respiration involves auto-oxidation of sugars leading to the production of reactive oxygen species (ROS).

In this article, the author discusses a research related to the functional analysis of the aldo-keto reductase (AKR4C) subfamily of Arabidopsis thaliana. Topics discussed include trióse phosphate, methylglyoxal (MG), and plant diabetes. Other topics discussed include sugar metabolism in organisms involves the danger of suffering from cell damage due to sugar toxicity, respiration involves auto-oxidation of sugars leading to the production of reactive oxygen species (ROS).

In this article, the author discusses a research related to the functional analysis of the aldo-keto reductase (AKR4C) subfamily of Arabidopsis thaliana. Topics discussed include trióse phosphate, methylglyoxal (MG), and plant diabetes. Other topics discussed include sugar metabolism in organisms involves the danger of suffering from cell damage due to sugar toxicity, respiration involves auto-oxidation of sugars leading to the production of reactive oxygen species (ROS).