Autophagy-Associated Shrinkage of the Hepatopancreas in Fasting Male Macrobrachium rosenbergii Is Rescued by Neuropeptide F

Invertebrate neuropeptide F-I (NPF-I), much alike its mammalian homolog neuropeptide Y, influences several physiological processes, including circadian rhythms, cortical excitability, stress response, and food intake behavior. Given the role of autophagy in the metabolic stress response, we investigated the effect of NPF-1 on autophagy during fasting and feeding conditions in the hepatopancreas and muscle tissues of the male giant freshwater prawn Macrobrachium rosenbergii. Starvation up-regulated the expression of the autophagy marker LC3 in both tissues. Yet, based on the relative levels of the autophagosome-associated LC3-II isoform and of its precursor LC3-I, the hepatopancreas was more responsive than the muscle to starvationinduced autophagy. Injection of NPF-I inhibited the autophagosome formation in the hepatopancreas of fasting prawns. Relative to the body weight, the muscle weight was not affected, while that of the hepatopancreas decreased upon starvation and NPF-1 treatment could largely prevent such weight loss. Thus, the hepatopancreas is the reserve organ for the nutrient homeostasis during starvation and NPF-I plays a crucial role in the balancing of energy expenditure and energy intake during starvation by modulating autophagy

Autophagy-Associated Shrinkage of the Hepatopancreas in Fasting Male Macrobrachium rosenbergii Is Rescued by Neuropeptide F

Invertebrate neuropeptide F-I (NPF-I), much alike its mammalian homolog neuropeptide Y, influences several physiological processes, including circadian rhythms, cortical excitability, stress response, and food intake behavior. Given the role of autophagy in the metabolic stress response, we investigated the effect of NPF-1 on autophagy during fasting and feeding conditions in the hepatopancreas and muscle tissues of the male giant freshwater prawn Macrobrachium rosenbergii. Starvation up-regulated the expression of the autophagy marker LC3 in both tissues. Yet, based on the relative levels of the autophagosome-associated LC3-II isoform and of its precursor LC3-I, the hepatopancreas was more responsive than the muscle to starvation-induced autophagy. Injection of NPF-I inhibited the autophagosome formation in the hepatopancreas of fasting prawns. Relative to the body weight, the muscle weight was not affected, while that of the hepatopancreas decreased upon starvation and NPF-1 treatment could largely prevent such weight loss. Thus, the hepatopancreas is the reserve organ for the nutrient homeostasis during starvation and NPF-I plays a crucial role in the balancing of energy expenditure and energy intake during starvation by modulating autophagy

The effects of biogenic amines, gonadotropin-releasing hormones and corazonin on spermatogenesis in sexually mature small giant freshwater prawns, Macrobrachium rosenbergii (De Man, 1879)

Neurotransmitters such as the serotonin (5-HT) and dopamine (DA), as well as the neurohormones gonadotropin-releasing hormones (GnRHs) and corazonin (Crz), are known to have various effects on decapod crustaceans, including ovarian maturation and spermatogenesis. The effects of these neurotransmitters and neurohormones on spermatogenesis in the small male freshwater prawns, Macrobrachium rosenbergii, have not been reported. So, we undertook histological and histochemical observations, as well as germ cell proliferation assays to examine the effects of 5-HT, DA, two exogenous GnRH isoforms (l-GnRH-III and oct-GnRH) and Crz. Ten experimental groups were injected with 5-HT and DA at 2.5 × 10−7 and 2.5 × 10−6 mol/prawn, and l-GnRH-III, oct-GnRH and Crz at 50 and 500 ng/gBW, at 4-day intervals from days 0 to 16. We found that prawns treated with 5-HT and GnRH isoforms exhibited significant increases in their testis-somatic index (TSI), seminiferous tubules at early maturation, i.e., stages I and III, with increased diameter of the tubules (DST), and germ cell proliferation, by days 4, 12 and 16, compared with saline control groups. In contrast, prawns treated with DA and Crz showed mostly seminiferous tubules at late maturation stages VIII and IX, and decreases of TSI, DST, and cell proliferation, by day 12, compared with saline control groups. By day 16 the Crz-treated prawns had died. These data indicate that 5-HT and GnRHs can stimulate spermatogenesis, while DA and Crz inhibit spermatogenesis. Consequently, hormonal treatment of male broodstocks in aquaculture with 5-HT and GnRHs could provide valuable tools to enhance reproduction by accelerating testicular maturation, leading to increased production of sperm

Changes of phosphatidylcholine and fatty acids in germ cells during testicular maturation in three developmental male morphotypes of Macrobrachium rosenbergii revealed by imaging mass spectrometry.

Testis maturation, germ cell development and function of sperm, are related to lipid composition. Phosphatidylcholines (PCs) play a key role in the structure and function of testes. As well, increases of polyunsaturated fatty acids (PUFA) and highly unsaturated fatty acids (HUFA), especially arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are essential for male fertility. This study is the first report to show the composition and distribution of PCs and total fatty acids (FAs) in three groups of seminiferous tubules (STs) classified by cellular associations [i.e., A (STs with mostly early germ cells), B (STs with mostly spermatids), and C (STs with spermatozoa)], in three morphotypes of Macrobrachium rosenbergii, [i.e., small male (SM), orange claw male (OC), and blue claw male (BC)]. Thin layer chromatography exhibited levels of PCs reaching maxima in STs of group B. Imaging mass spectrometry showed remarkably high signals corresponding to PC (16:0/18:1), PC (18:0/18:2), PC (18:2/20:5), and PC (16:0/22:6) in STs of groups A and B. Moreover, most signals were detected in the early developing cells and the intertubular area, but not at the area containing spermatozoa. Finally, gas chromatography-mass spectrometry indicated that the major FAs present in the testes were composed of 14:0, 16:0, 17:0, 18:0, 16:1, 18:1, 18:2, 20:1, 20:2, 20:4, 20:5, and 22:6. The testes of OC contained the greatest amounts of these FAs while the testes of BC contained the least amounts of these FAs, and there was more EPA (20:5) in the testes of SM and OC than those in the BC. The increasing amounts of FAs in the SM and OC indicate that they are important for spermatogenesis and spermiogenesis. This knowledge will be useful in formulating diets containing PUFA and HUFA for prawn broodstocks in order to improve testis development, and lead to increased male fecundity

Separation and identification of phosphatidylcholines (PCs) by thin-layer chromatography (TLC) showing bands duplicated bands (upper panels) and histograms of the intensity of PCs (lower panel) in (A) each group of seminiferous tubules (ST), and (B) testes of the three developmental male morphotypes.

<p>Group B STs, containing mostly spermatids and some immature spermatozoa, show significant differences of PCs intensities compared with groups A and C (<i>P</i><0.05; means ± S.D.; n = 5). The data support the IMS results of the PC (16:0/18:1). Moreover, the testes of OC males also contain significantly more PCs than those of SM and BC males (<i>P</i><0.05). SM = small male; OC = orange claw male; BC = blue claw male. Bar = S.D.; * = significant difference at <i>P</i><0.05.</p

IMS showing different intensities and distributions of PCs in each group of seminiferous tubules in cryosections of the OC males (d-o), compared with picture of the same sections stained with H&E (a-c).

<p>The signals appear mainly in developing germ cells of the three groups of STs. The highest intensity corresponding to the signal at m/z 798.5, representing PC (16:0/18:1) appears in the STs of group A and B which contain mostly developing cells (d-e), and in the STs of group C which contain only mature sperms (f). The signals at m/z 808.5, representing PC (18:0/18:2 linoleic acid or LA), and <i>m/z</i> 826.5, representing PC (18:2/20:5 eicosapentaenoic acid or EPA), appear in the STs of groups A and B (g-l). The signal at <i>m/z</i> 872.5, representing PC (18:0/22:6 docosahexaenoic acid or DHA), appears in the STs of group A only (m-o). Sc = spermatocytes; Sz = spermatozoa; St = spermatids; IT = intertubular area; Scale bars = 200 μm; Relative intensity bar shows the intensity level of the ion images.</p

IMS showing the intensity and distribution of PCs in the STs of OC males at high magnifications.

<p>Micrographs from H&E-stained sections (a-c) show areas surrounded by white dashed lines corresponding to the same areas that display ion images (d-o). Groups A and B STs containing mostly developing cells, and intertubular area (IT) (d-e, g-h, j-k, m-n), show higher levels of the signal intensity compared with group C STs, which contains only mature spermatozoa (Sz) (surrounded by orange dashed circle) (f, i, l, o). The areas containing Sz have very low signal intensities in all groups. Sc = spermatocytes; St = spermatids; Scale bars = 200 μm; Relative intensity bar shows the intensity level of the ion images.</p

Gas Chromatography-mass spectrometry (GC-MS) analyses show (A) the FAs per testicular weight (mean ± SD; n = 5), and (B) the ratios between each FA per total FAs in the testes of the three developmental male morphotypes.

<p>(A) the FAs which were detected in the testes of the three morphotypes consisted of 14:0, 15:0, 16:0, 17:0, 18:0, 16:1, 18:1, 18:2, 20:1, 20:2, 20:4, 20:5, and 22:6. In term of relative quantities it was shown that the OC testes contained highest amounts of FAs 16:0, 18:0, 16:1, 18:1, 18:2, 20:1, and contained higher amounts of 14:0, 15:0, and 20:2 when compared with BC while the differences were not significant when compared to SM. Moreover, testes of SM and OC contained higher amounts of FAs 17:0, and 20:5 (EPA) when compared to BC, whereas FAs 20:4 (ARA) and 22:6 (DHA) showed no statistical difference among the testes of the three groups. (B) FA ratios showed that the testes of SM contained higher accumulations of 17:0, 20:1, 20:2, 20:5 (EPA) and 22:6 (DHA) when compared with OC while there were no significant differences between SM and BC. 20:4 = ARA, Arachidonic acid; 20:5 = EPA, Eicosapentaenoic acid; 22:6 = DHA, Docosahexaenoic acid; SM = small male; OC = orange claw male; BC = blue claw male; * = significant difference at P<0.05.</p

MS/MS and IMS identifications and distributions of phosphatidylcholines (PCs) in three groups of seminiferous tubules (STs).

<p>^a--, not detected.</p><p>MS/MS and IMS identifications and distributions of phosphatidylcholines (PCs) in three groups of seminiferous tubules (STs).</p