Insect diuretic hormones are crucial for control of water balance. We isolated from the cockroach Diploptera punctata two diuretic hormones (DH), Dippu-DH31 and Dippu-DH46, which increase cAMP production and fluid secretion in Malpighian tubules of several insect species. Dippu-DH 31 and -DH46 contain 31 and 46 amino acids, respectively. Dippu-DH46 belongs to the corticotropin-releasing factor (CRF)-like insect DH family, whereas Dippu-DH 31 has little sequence similarity to the CRF-like DH, but is similar to the calcitonin family. Dippu-DH46 and -DH31 have synergistic effects in D. punctata but have only additive effects in Locusta migratoria. Dippu-DH31 represents a distinct type of insect DH with actions that differ from those of previously identified insect peptides with diuretic activity.Malpighian tubules ͉ corticotropin-releasing factor ͉ Diploptera punctata ͉ Locusta migratoria ͉ Manduca sexta I n insects, urine production by the Malpighian tubules (Mt) is driven by hormonally controlled active transport processes, rather than by ultrafiltration, as in vertebrates. There are several families of insect diuretic peptides, including myokinins, which increase urine production by elevating intracellular Ca 2ϩ (1, 2), and the ''corticotropin-releasing factor (CRF)-like'' diuretic hormones (DH), which act via cAMP (3). CRF-like DH have been identified from eight species in five insect orders (4-14); they are similar to the sauvagine͞CRF͞urotensin I͞urocortin family of vertebrate peptides.For some years, only Manduca sexta was known to possess two CRF-like DH, Manse-DH (4) and Manse-DPII (9). Manse-DPII is shorter (30 residues) than other known DH and has lower sequence similarity with other DH than does Manse-DH. However, in 1998, we identified a second DH from Tenebrio molitor, termed Tenmo-DH 47 (12) to distinguish this peptide from the known Tenmo-DH 37 (11). More recently we identified two DH from Hyles lineata (a sphingid moth closely related to M. sexta), Hylli-DH 30 and Hylli-DH 41 , which each differ at only one residue from their M. sexta counterparts. Thus, in at least three insect species, two DH exist. The extent of sequence similarity between these ''long'' and ''short'' DH indicates that they belong to the same peptide family. However, they are most likely paralogous sequences (arising from a gene duplication event), as is the case for fish CRF and urotensin I. The lower potency of Tenmo-DH 47 vs. Tenmo-DH 37 (12) suggests for it a somewhat different role, just as urocortin, an orthologue of urotensin I (15), has effects that differ in vivo from those of CRF (16,17).We now report the identification of two DH from brain and corpora cardiaca (CC) of the Pacific beetle cockroach (Diploptera punctata), one of which (Dippu-DH 31 ) is a peptide with biological properties that differ from those of the CRF-like DH. Materials and MethodsInsects. D. punctata were maintained as described previously (18). Brains and CC were dissected from adult males 2-10 days old. For bioassays, newly emerged adult males wer...

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Large colored β-Si3N4 single crystals were successfully grown from a Si melt in N2. The transmission optical absorption of coloring β-Si3N4 single crystal shows that impurities introduce a midgap level of ∼2.4 eV into the wide band gap of ∼5.3 eV in nondoped Si3N4. The infrared transmission spectrum and electron probe x-ray microanalysis of β-Si3N4 samples show that the solution of the Al element affects the silicon–nitrogen molecular vibration and the states within the band gap of β-Si3N4. The obtained results mean that the Al impurity acts as the radiative center and is the origin of the color in the β-Si3N4 single crystal.