Cannibalistic feeding behavior of the brackish-water copepod Sinocalanus tenellus

Cannibalistic feeding behavior of the brackish-water copepodSinocalanus tenellus was examined in the laboratory using CI-II,CIII-IV and CVI female as predators and NI-II, NIII-IV, NV-VIand CI-II as prey. In each prey-predator combination, the ingestionrate increased with increasing prey density to an asymptoticvalue. Cannibalism took place even when phytoplankton was availableas an alternative food supply. Based on a daily ration, theoptimal prey stages for CVI females, CIII-IV and CI-II are NI-VI,NI-IV and NI-II respectively. Under average, natural prey density(10 nauplii l^–1), S tenellus can achieve only a smallfraction (max 9%) of the daily minimum food requirement by cannibalisticfeeding. However, the impact of cannibalism on naupliar survivorshipcan be significant. When adult females occur at a density of10 l^–1, the mortality due to cannibalism attains 99.2%during the naupliar stages.     

Immunohistochemical distribution of simple-epithelial-type keratins and other intermediate filament proteins in the developing human pituitary gland

Summary An immunohistochemical study of the production of the intermediate filaments [vimentin, cytokeratin, and glial filament acidic protein (GFAP)] during development of the pituitary gland was made by use of fetal and adult human pituitary tissue. Among these intermediate filament proteins in the anterior and intermediate lobes of the pituitary, cytokeratin is the first to appear, followed by GFAP and vimentin. However, only cytokeratin is seen during the period of morphogenesis of the pituitary gland, with the type-II subfamily cytokeratin 8 being the earliest to appear. Among the simple-epithelial-type cytokeratins, cytokeratins 8 and 19 were observed within the pituitary primordium during morphogenesis. Cells immunoreactive for cytokeratins 8 and 19 showed a heterogeneous three-dimensional distribution pattern in Rathke's pouch. Both cytokeratins 8 and 19 tended to be strongly positive at sites in the pituitary primordium where cells had become more loosely arranged (i.e., areas far from the diencephalon) but were only weakly positive in areas in which the epithelial cells were densely packed (i.e., areas closely associated with the diencephalon). It is concluded that, during the period of morphogenesis, Rathke's pouch has the intermediate filaments characteristic of simple epithelium and shows different immunoreactivity for simple-epithelial-type cytokeratins from place to place according to the extent of cellular differentiation.     

Structural and functional analysis of a polyoma-related mammalian plasmid (L factor): the enhancer activity and plasmid establishment.

L factor is a unique plasmid DNA which was originally discovered in a subclone (B822) of mouse L cells at a high copy number (more than 5,000 copies/cell). The presence of L factor caused no detectable abnormalities to the plasmid-bearing cells. We determined the total DNA sequence of the L factor I (and a part of L factor II) and compared it with that of polyoma DNA. Both DNA are common to the general construction of DNA frames such as early, late and noncoding regions, suggesting the two to be closely related. On the other hand, the L factor DNA sequences differ substantially from that of polyoma in the DNA sequences corresponding to the polyoma large T antigen, capsid proteins and a portion of the enhancer region. In order to investigate the mechanism of plasmid establishment of L factor, we compared the enhancer activity, capacity of DNA replication and efficiency of plasmid establishment of L factor with those of polyoma. The results indicate that L factor enhancer activity and DNA replication capacity were considerably lower than those of polyoma, suggesting that these altered (lowered) activities associated with L factor contribute to the plasmidal establishment and stable maintenance of L factor.     

Association of Lps gene with natural resistance of mouse macrophages against Legionella pneumophila

We have cloned a 1.6-kb region of chromosomal DNA from Thermoplasma acidophilum into Escherichia coli using as a probe part of the Methanococcus vannielii fus-gene. The sequence of the clone was highly homologous to part of the corresponding Methanococcus vannielii gene. By chromosome walking, a 4.7-kb EcoRI fragment containing the complete gene was isolated. Nucleotide sequencing revealed an open reading frame of 2196 nucleotides. The deduced amino acid sequence contains the known peptide sequence around the ADP-ribosylation site of T. acidophilum elongation factor 2, which unequivocally confirms that the fus-gene has been cloned. The amino acid sequence was compared to that of hamster and E. coli, as well as to known archaebacterial EF-2 sequences.     

Comparative anatomical study of arteriographs of the hand of primates. Deep palmar arterial arches and their correlating arteries in cercopithecidae, pongidae and hominidae

A three-dimensional angiographic analysis of the deep palmar arterial arches and their correlating arteries in Cercopithecidae, Pongidae and Hominidae revealed the following features. In Cercopithecidae, 3 deep palmar arches are formed by the perforating branches of the 2nd dorsal metacarpal artery: 2 proximal arches (the catella volaris proximalis and the arcus volaris profundus) and 1 distal arch (the catella volaris distalis). The intermetacarpal arteries arise from the catella volaris proximalis and the palmar metacarpal arteries arise from the arcus volaris profundus. In Pongidae, the arches are formed by the perforating branches of the 1st dorsal metacarpal artery, and they are composed of only the catella volaris proximalis and catella volaris distalis. In Hominidae, the arches are formed by the perforating branches of the 1st dorsal metacarpal artery, and they consist of the arcus volaris profundus and an incomplete catella volaris distalis.     

Selective potentiation of 5-methyl-2-(1-methylcyclohexyl)-4-oxazoleacetic acid (AD-4610) on glucose-induced insulin secretion

In the perfused pancreas from normal SD rats, AD-4610 (0.01-0.1 mM) potentiated biphasic insulin secretion induced by 7.5 mM of glucose. The concentration-response curve of insulin secretion to glucose was shifted leftwards with AD-4610 (0.1 mM) without altering either the threshold concentration of glucose to induce insulin secretion or the maximal insulin response to glucose, indicating increased sensitivity of the pancreatic B-cells to glucose. On the other hand, AD-4610 was 10-fold less effective in altering insulin secretion induced by arginine and glyceraldehyde. The effect of AD-4610 on insulin secretion and glucose metabolism was compared with that of tolbutamide in vivo. AD-4610 (100 mg/kg) potentiated insulin secretion induced by an intravenous glucose load, and also accelerated glucose metabolism without altering basal insulin secretion in normal rats. On the other hand, tolbutamide (20 mg/kg) increased basal insulin secretion, but slightly decreased glucose-induced insulin secretion. In yellow KK mice with hyperglycemia, AD-4610 (10-100 mg/kg) had a dose-dependent hypoglycemic action, but tolbutamide did not. Thus, AD-4610 stimulated insulin secretion in a glucose-dependent fashion and enhanced glucose metabolism in vivo. These results suggest that AD-4610 selectively potentiates glucose-induced insulin secretion by increasing the sensitivity of pancreatic B-cells to glucose and may be useful for treating human NIDDM through a different mechanism than that of tolbutamide.     

Rubredoxin as an intermediary electron carrier for nitrate reduction by NAD(P)H in Clostridium perfringens

The NAD(P)H-dependent nitrate reductase system in Clostridium perfringens was reconstituted with rubredoxin (Rd), nitrate reductase (NaR), and an unadsorbed fraction, on a DEAE-cellulose column, of the extract (designated as fraction A), under nitrogen gas. Ferredoxin in place of Rd was not effective as an electron carrier in this reconstituted system. NAD(P)H-dependent nitrate reducing activity was also obtained by replacing fraction A with ferredoxin-NADP+ reductase from spinach. We propose the following scheme for the electron transfer in this NAD(P)H dependent nitrate reduction system. NAD(P)H----NAD(P)H-Rd reductase----Rd----NaR----NO3-.     

Molecular cloning of complementary DNA encoding one of the human pancreatic protease E isozymes

We have cloned a DNA from a human pancreatic cDNA library using a cloned rat pancreatic elastase 1 cDNA as a probe, and determined its nucleotide sequence. This cDNA contains a coding region of 810 nucleotides which encodes a 270-amino-acid protein. The deduced amino acid sequence shows less than 60% homologies with rat and porcine pancreatic elastase 1, although its substrate binding region is homologous with those of the above elastases 1. When this deduced amino acid sequence was compared with known amino acid sequences of pancreatic proteases other than elastases, it was found to contain an amino acid sequence which was highly homologous with the N-terminal amino acid sequence of porcine pancreatic protease E. We also purified human pancreatic protease E isozymes from human pancreatic juice, and determined their N-terminal amino acid sequences. One of the isozymes does not hydrolyze elastin but does hydrolyze a synthetic substrate. Endoglycosidase F digests glycoside bonds of the isozyme. These results suggest that the cDNA cloned by us corresponded to one of the human protease E isozymes.     

Affinity purification of human deoxycytidine kinase: avoidance of structural and kinetic artifacts arising from limited proteolysis

Homogeneous deoxycytidine kinase has been isolated from leukemic human T-lymphoblasts by affinity chromatography based on a multisubstrate analog, deoxycytidine 5'-adenosine 5"'-P1,P4-tetraphosphate (dCp4A). Chromatography of extract treated with protease inhibitors yielded a monomeric polypeptide, inasmuch as the Mr of the native protein, 59,300, is comparable to the value of 52,000 from sodium dodecyl sulfate polyacrylamide gel electrophoresis. The isoelectric pH was 6.1. But, enzyme isolated without protease inhibitors exhibited two fragments of Mr = 30,000 and 33,000, suggesting that proteolytic cleavage of the parental polypeptide had occurred during affinity chromatography. Both the parental and proteolyzed enzymes phosphorylated deoxyadenosine and deoxyguanosine, as well as deoxycytidine. However, the proteolyzed enzyme had an increased apparent Km for deoxycytidine. In consequence of this, a mixture of the two forms produced bimodal kinetic plots, whereas linear kinetics were displayed by each form alone.     

Cloning of mRNA sequence coding for sex-specific storage protein of Bombyx mori

A major plasma protein, referred to as SP 1, exhibits sex- and stage-specific expression during the larval development of the silkworm, Bombyx mori. We have isolated a plasmid clone bearing a part of mRNA sequence coding for SP 1 and quantitated the amount of SP 1 mRNA by means of RNA blot hybridization using the cDNA probe. The developmental change in the amount of SP 1 mRNA in the fat body closely reflected that of the hemolymph concentration of SP 1, indicating that the biosynthesis of SP 1 is regulated in a sex- and developmental stage-specific fashion at the level of mRNA.