No abstract

No abstract

We previously analyzed the central nervous system (CNS) transcriptome and found three isotypes of long neuropeptide F (MrNPF-I, -II, -III) and four isoforms of short NPF (sMrNPF) in the giant freshwater prawn, Macrobrachium rosenbergii. We now validate the complete sequences of the MrNPF-I and -II precursor proteins, which show high similarity (91-95 %) to NPFs of the penaeus shrimp (PsNPF). MrNPF-I and -II precursors share 71 % amino acid identity, whereas the mature 32-amino-acid MrNPF-I and 69-amino-acid MrNPF-II are identical, except for a 37-amino-acid insert within the middle part of the latter. Both mature MrNPFs are almost identical to PsNPF-I and -II except for four amino acids at the mid-region of the peptides. Reverse transcription plus the polymerase chain reaction revealed that transripts of MrNPF-I and -II were expressed in various parts of CNS including the eyestalk, brain and thoracic and abdominal ganglia, with the highest expression occurring in the brain and thoracic ganglia and with MrNPF-I showing five- to seven-fold higher expression than MrNPF-II. These peptides were also expressed in the midgut hindgut, and hepatopancreas, with MrNPF-I expression in the former two organs being at the same level as that in the brain and thoracic ganglia and about 4-fold higher than NPF-II. The expression of NPFs was also detected in the testes and spermatic duct but appeared much weaker in the latter. Other tissues that also expressed a considerable amount of NPF-I included the hematopoeitic tissue, heart and muscle. By immunohistochemistry, we detected MrNPFs in neurons of clusters 2, 3 and 4 and neuropils ME, MT and SG of the optic ganglia, neurons in cluster 6 and neuropils AMPN, PMPN, PT, PB and CB of the medial protocerebrum, neurons in clusters 9 and 11 and neurophils ON and OGTN of the deutocerebrum and neurons in clusters 14, 15 and 16 and neuropils TN and AnN of the tritocerebrum. Because of their high degree of conservation and strong and wide-spread expression in tissues other than CNS, we believe that, in addition to being a neuromodulator in controlling feeding, MrNPFs also play critical roles in tissue homeostasis. This should be further explored.

No abstract

Autophagy is a degradative process of cellular components accomplished through an autophagosomal-lysosomal pathway. It is an evolutionary conserved mechanism present in all eukaryotic cells, and it plays a fundamental role in maintaining tissue homeostasis both in vertebrates and invertebrates. Autophagy accompanies tissue remodeling during organ differentiation. Several autophagy-related genes and proteins show significant upregulations following nutrient shortage (i.e., starvation). In our previous study, we found that in female giant freshwater prawns subjected to a short period of starvation autophagy was up-regulated in consonant with ovarian maturation and oocyte differentiation. Whether and how starvation-induced autophagy impacts on testicular maturation and spermatogenesis of the male prawns remained to be investigated. In this study, we analyzed the effects of starvation on histological and cellular changes in the testis of the giant freshwater prawn Macrobrachium rosenbergii that paralleled the induction of autophagy. Under short starvation condition, the male prawns showed increased gonado-somatic index, increased size, and late stage of maturation of seminiferous tubules, which contained increased number of spermatozoa. Concurrently, the number of autophagy vacuoles and autophagy flux, as monitored by transmission electron microscopy and the autophagic marker LC3, increased in the testicular cells, indicating that a short period of starvation could induce testicular maturation and spermatogenesis in male M. rosenbergii along with modulation of autophagy.