Collateral flow resistance and time constants in dog and horse lungs

We studied collateral flow resistance in exsanguinated, excised lower lobes and accessory lobes of dog and horse lungs, respectively. A double lumen catheter obstructed a peripheral airway isolating a segment of the lobe. Oxygen flowed into the segment via a rotameter which measured flow (Vcoll) while the inner catheter recorded segment pressure (Ps). Gas delivered into the segment flowed out via collateral channels. Collateral flow resistance was calculated as (Ps - PL)/Vcoll, where PL = static transpulmonary pressure. Rcoll at PL = 20, 10, and 5 cm H2O averaged 0.24, 1.25, and 2.65 cmH2O.ml-1.s, respectively, in the dog, and 4.53, 6.00, and 12.62 cmH2O.ml-1.s in the horse. At a given PL, Rcoll measured during inflation. At constant PL, Rcoll increased with time at PL = 5 and 10 cmH2O, but was not time dependent at PL = 20 cmH2O. At constant PL, Rcoll increased at Vcoll increased. We conclude Rcoll is greater in horses than in dogs and is a function of PL, Ps - PL, and lung volume history in both species.     

The five-parameter logistic: a characterization and comparison with the four-parameter logistic

Improvements in assay technology have reduced the amount of random variation in measured responses to the point where even slight asymmetry of the assay data can be more significant than random variation. Use of the five-parameter logistic (5PL) function to fit dose-response data easily accommodates such asymmetry. The 5PL can dramatically improve the accuracy of asymmetric assays over the use of symmetric models such as the four-parameter logistic (4PL) function. Until recently, however, the process of fitting the 5PL function has been difficult, with the result that the 4PL function has continued to be used even for highly asymmetric data. Various ad hoc modifications of the 4PL method have been developed in an attempt to address asymmetric data. However, recent advances in numerical methods and assay analysis software have rendered easier the fitting of the 5PL routine. This paper demonstrates how use of the 5PL function can improve assay performance over the 4PL and its variants. Specifically, the improvement in the accuracy of concentration estimates that can be obtained using the 5PL over the 4PL as a function of the asymmetry present in the data is studied. The behavior of the 5PL curve and how it differs from the 4PL curve are discussed. Common experimental designs, which can lead to ill-conditioned regression problems, are also examined.     

Genetic and litter size effects on serum placental lactogen in the mouse

Placental lactogen (PL) and progesterone are important hormones of pregnancy in the mouse. The purpose of this study was to investigate the influence of genetic differences and litter size on serum PL levels in the mouse. Serum progesterone levels were also measured in some experiments. Two features of serum PL levels under genetic control were identified: 1) the gestational profile of serum PL and 2) absolute serum PL levels. Breeding combinations that resulted in profound effects on serum PL levels were without significant affect on serum progesterone levels. Serum concentrations of PL and progesterone were directly proportional to litter size. Conceptus number was found to significantly affect ovarian progesterone release. The presence of uterine tissue antagonized the luteotropic actions of the conceptus but did not affect serum PL levels.     

Pluronic L81 enhances triacylglycerol accumulation in the cytosol and inhibits chylomicron secretion

Pluronic L81 (PL81) inhibits fat absorption, and other Pluronic copolymers help overcome drug resistance in cancer cells. To understand how PL81 acts, we synthesized a radiolabeled analog, [14C]PL81, and showed that it was structurally similar to PL81 based on (1)H NMR as well as mass spectrometric analysis. [14C]PL81 inhibited the secretion of chylomicrons (CMs), lipoproteins essential for fat absorption, by differentiated Caco-2 cells similar to PL81. Moreover, PL81 competed with the cellular uptake of [14C]PL81. Thus, [14C]PL81 and PL81 behave similarly in these physiologic assays. Uptake of [14C]PL81 by Caco-2 cells was concentration-, time-, and temperature-dependent and occurred mainly from the apical side. Intracellularly, it was assimilated in the cytosol. Cells excreted PL81 toward the apical side via a pathway partially sensitive to verapamil. Small amounts were secreted toward the basolateral side unassociated with CM, and this secretion was unaffected by the inhibition of CM assembly. Nonetheless, PL81 significantly inhibited the secretion of triacylglycerols (TGs) and phospholipids as part of CM. PL81-treated cells showed decreased activity of microsomal triglyceride transfer protein and accumulated more TGs, but not phospholipids, in their cytosol. We propose that Pluronic copolymers act by interfering with the export of molecules from the cytosol. They inhibit fat absorption by decreasing TG transport to the endoplasmic reticulum and increase drug efficacy against cancer cells by competing for their excretion.     

Effect of high dietary zinc on plasma ceruloplasmin and erythrocyte superoxide dismutase activities in Copper-depleted and repleted rats

The effect of moderately high dietary zinc (Zn) on the activities of plasma (PL) ceruloplasmin (CP), and PL and erythrocyte (RBC) copper (Cu), Zn superoxide dismutase (SOD) was determined in weanling rats fed Cu-deficient (DEF; <1 mg Cu/kg), marginal (MAR; 2 mg Cu/kg), or control (CON; 5 mg Cu/kg) copper diets containing normal or high Zn (HZn; 60 mg/kg) for 4 wk and supplemented with oral Cu (CuS; 5 mg/L) in drinking water for 0, 1, 3, or 7 d. PL Cu decreased (67% compared to CON;p≤0.05) in the DEF and increased to control level after 3 d of CuS; increased in the MAR group after 1 d of CuS. HZn reduced overall PL Cu by 27% in all groups, but did not alter the linear increase in PL Cu between 0 and 3 d of Cu S. PL CP activity altered concomitantly with PL Cu levels: The time course of increase in CP activity after 0–3 d of CuS was not influenced by HZn in the diet and CP declined in the DEF group by 92%. There was no correlation between dietary Cu level and PL CP. PL SOD activity decreased by 46% (p≤.05) in the DEF group, increased to control activity after 1 d of CuS and declined slighty after 7 d; MAR diet did not alter PL SOD. HZn diet increased PL SOD activity in all groups by 150%, reduced activity in the DEF and MAR groups by 65 and 37% and delayed the recovery of PL SOD after CuS. RBC SOD declined in the DEF and MAR groups by 56 and 33% (p≤0.05) and did not respond to CuS; HZn diet did not influence RBC SOD activity. These data indicate that moderately high Zn in the diet reduces PL Cu, but not PL CP activity or the recovery of PL Cu or CP activity after oral CuS of Cu-deficient rats, modifies the response of PL SOD to dietary Cu, but does not influence RBC SOD activity.     

In vitro fusion of Acanthamoeba phagolysosomes. II Quantitative characterization of in vitro vacuole fusion by improved electron microscope and new light microscope techniques

To investigate the properties of phagolysosome (PL) fusion in Acanthamoeba homogenates, it was necessary to develop reliable methods for measuring in vitro PL fusion. The need to distinguish PL fusion from PL adhesion was met by the development of a quantitative electron microscope assay. Initial characterization of the fusion reaction by this method was followed by the development of a more rapid light microscope assay. Results obtained by the two methods were found to be in close agreement. By use of these new techniques, the in vitro PL fusion reaction was demonstrated to occur in a quantitatively reproducible manner. Under the present conditions employed, PL breakdown was not detected at any time during the in vitro incubation, while PL fusion was observed to proceed linearly for approximately 10 min, at which time the reaction ceased. Incubation of mixtures of two distinct PL types resulted in increases in hybrid PL types that were paralleled by decreases in nonhybrid PL types. The relative changes in PL concentrations observed were quantitatively consistent with PL fusion occurring randomly with respect to PL type. PL fusion was strongly inhibited by low concentrations of KF (50% inhibition at 2.7 mM), and by approximately tenfold higher concentrations of KCl, while KCN and 2,4-dinitrophenol (2,4-DNP) had little effect. In addition to further defining the nature of the PL fusion reaction in this system, these results demonstrate that, by use of the techniques described, quantitative study of the biochemical properties of this reaction is now possible.     

Neutral Lipid Metabolism Influences Phospholipid Synthesis and Deacylation in Saccharomyces cerevisiae

Establishment and maintenance of equilibrium in the fatty acid (FA) composition of phospholipids (PL) requires both regulation of the substrate available for PL synthesis (the acyl-CoA pool) and extensive PL turnover and acyl editing. In the present study, we utilize acyl-CoA synthetase (ACS) deficient cells, unable to recycle FA derived from lipid deacylation, to evaluate the role of several enzymatic activities in FA trafficking and PL homeostasis in Saccharomyces cerevisiae. The data presented show that phospholipases B are not contributing to constitutive PL deacylation and are therefore unlikely to be involved in PL remodeling. In contrast, the enzymes of neutral lipid (NL) synthesis and mobilization are central mediators of FA trafficking. The phospholipid:DAG acyltransferase (PDAT) Lro1p has a substantial effect on FA release and on PL equilibrium, emerging as an important mediator in PL remodeling. The acyl-CoA dependent biosynthetic activities of NL metabolism are also involved in PL homeostasis through active modulation of the substrate available for PL synthesis. In addition TAG mobilization makes an important contribution, especially in cells from stationary phase, to FA availability. Beyond its well-established role in the formation of a storage pool, NL metabolism could play a crucial role as a mechanism to uncouple the pools of PL and acyl-CoAs from each other and thereby to allow independent regulation of each one.     

Phospholipids and blood coagulation]

After a simplified survey of the chemistry of phospholipids (PL) their presence in the lipid part of thromboplastin is dealt with, the significance of this structure being stressed. In addition, the condition, mode of action and synthesis of PL in blood platelets are extensively discussed and the impact of the composition of thrombocytic PL in the membrane and granular fraction by plasma lipid substances is referred to. The relations between single forms of PL and those proteins activating coagulation are represented and the conditions for the development of such activating complexes are referred to. Subsequently the coagulation stimulating properties of PL, thromboplastin, thrombocytes, and artifically produced PL are compared and the attempt is made to draw certain conclusions from sometimes contradictory results. Finally, the anticoagulative effect of phosphatidylserin is referred to.     

Alternatively activated macrophages regulate extracellular levels of the hormone placental lactogen via receptor-mediated uptake and transcytosis

Alternatively activated (M2) macrophages regulate immune responses and tissue remodelling. In many tissues including placenta, M2 express stabilin-1, a multidomain protein that exerts a dual role as a scavenger receptor for acetylated low density lipoprotein (acLDL) and SPARC (secreted protein acidic and rich in cysteine) and as an intracellular cargo carrier for SI-CLP. Using yeast two-hybrid screening, we identified the developmental hormone placental lactogen (PL) as a novel ligand of stabilin-1. In Chinese hamster ovary-stabilin-1 cells and M2, FACS and confocal microscopy demonstrated that stabilin-1 mediates internalization and endosomal sorting of PL. In M2 macrophages, PL was partially degraded in lysosomes; part of PL escaped degradation and was delivered to novel PL+ storage vesicles lacking endosomal/lysosomal markers. During formation, PL+ vesicles underwent transient interaction with the trans-Golgi network (TGN). Upon placement of PL-loaded M2 into PL-free medium, PL was secreted into the supernatant. Leupeptin, an inhibitor of lysosomal hydrolases, reduced PL degradation, enhanced sorting of PL into the TGN/storage vesicle pathway and increased PL secretion. Thus, processing of PL in M2 macrophages occurs either by the classical lysosomal pathway or by a novel TGN-associated trans-secretory pathway. Macrophages isolated from human placental villi efficiently endocytosed PL-FITC and transported it to the storage vesicles. Our data show that extracellular PL levels are determined by uptake, degradation, storage, and release in M2. During pregnancy PL concentration reaches 10 microg/ml in maternal circulation and stays below 0.5 microg/ml in fetal circulation. We propose that stabilin-1-positive macrophages determine the difference in PL levels between maternal and fetal circulation.     

Purification, characterization, and antifungal activity of chitinases from pineapple (Ananas comosus) leaf

Three chitinases, designated pineapple leaf chitinase (PL Chi)-A, -B, and -C were purified from the leaves of pineapple (Ananas comosus) using chitin affinity column chromatography followed by several column chromatographies. PL Chi-A is a class III chitinase having a molecular mass of 25 kDa and an isoelectric point of 4.4. PL Chi-B and -C are class I chitinases having molecular masses of 33 kDa and 39 kDa and isoelectric points of 7.9 and 4.6 respectively. PL Chi-C is a glycoprotein and the others are simple proteins. The optimum pHs of PL Chi-A, -B, and -C toward glycolchitin are pH 3, 4, and 9 respectively. The chitin-binding ability of PL Chi-C is higher than that of PL Chi-B, and PL Chi-A has lower chitin-binding ability than the others. At low ionic strength, PL Chi-B exhibits strong antifungal activity toward Trichoderma viride but the others do not. At high ionic strength, PL Chi-B and -C exhibit strong and weak antifungal activity respectively. PL Chi-A does not have antifungal activity.     

Floral adaptation and diversification under pollen limitation

Pollen limitation (PL) of seed production creates unique conditions for reproductive adaptation by angiosperms, in part because, unlike under ovule or resource limitation, floral interactions with pollen vectors can contribute to variation in female success. Although the ecological and conservation consequences of PL have received considerable attention in recent times, its evolutionary implications are poorly appreciated. To identify general influences of PL on reproductive adaptation compared with those under other seed-production limits and their implications for evolution in altered environments, we derive a model that incorporates pollination and post-pollination aspects of PL. Because PL always favours increased ovule fertilization, even when population dynamics are not seed limited, it should pervasively influence selection on reproductive traits. Significantly, under PL the intensity of inbreeding does not determine whether outcrossing or autonomous selfing can evolve, although it can affect which response is most likely. Because the causes of PL are multifaceted in both natural and anthropogenically altered environments, the possible outcrossing solutions are diverse and context dependent, which may contribute to the extensive variety of angiosperm reproductive characteristics. Finally, the increased adaptive options available under PL may be responsible for positive global associations between it and angiosperm diversity.     

Lysyl oxidase interacts with hormone placental lactogen and synergistically promotes breast epithelial cell proliferation and migration

Lysyl oxidase (LOX), an extracellular amine oxidase, catalyzes the cross-linking of collagen and elastin. LOX has been also shown to play an essential role in promoting the invasive and metastatic potential of breast tumor cells. However, the LOX-interacting factors in these processes are not known. In this study, we identified placental lactogen (PL), a member of the growth hormone/prolactin hormone family, as a LOX-interacting partner using yeast two-hybrid screens. PL is normally only expressed in placental syncytiotrophoblasts, but PL genes are amplified and expressed in a high percentage of invasive ductal breast carcinomas. We confirmed LOX-PL interactions using far Western and solid phase binding assays. In activity assays, PL was not a substrate or inhibitor of LOX. We further demonstrated that PL is expressed in breast tumor epithelial cells and detected LOX-PL interactions by coimmunoprecipitation in invasive breast cancer cells. In MCF-10A normal breast epithelial cells stably expressing LOX, PL, or both, LOX had no effect on cell proliferation, PL alone increased proliferation by 49%, and coexpression of LOX and PL led to a 121% increase in cell proliferation. Unlike in tumor cells, LOX did not induce a more migratory phenotype in MCF-10A cells; nor did PL. However, their coexpression resulted in a 240% increase in cell migration, suggesting that these interactions may be highly relevant to the transition of epithelial cells toward a migratory phenotype during the development and progression of breast carcinoma and a significant role for LOX-PL interactions in epithelial cell behavior.     

Spectral studies on the interaction of iodine and anthracene sulfonate with bacterial phospholipids from different mutants of Salmonella minnesota.

Using spectrophotometric and spectrofluorometric techniques, the interaction of iodine and 2-anthracene sulfonate (ANS) with the phospholipids (PL) isolated from four genetically correlated Salmonella minnesota isolates viz., a smooth form (S), a deeply rough mutant (Rc) and two intermediate forms (Ra and Rb) were studied. Appearance of an isosbestic point and a new band in absorption spectra indicated charge-transfer (C-T) interaction of iodine with the PL through the formation of 1:1 complex. Stern-Volmer type fluorescence quenching of PL was observed with the addition of iodine to PL, while PL enhanced the fluorescence of anionic dye ANS. The values of the binding constants between iodine/PL and ANS/PL, measured by using suitable equations, showed a systematic gradation in the molecular properties of the PL in the membrane structure in smooth (S) and rough (Ra, Rb and Rc) mutants of Salmonella minnesota.     

Studies on the origin of biliary phospholipid. Effect of dehydrocholic acid and cholic acid infusions on hepatic and biliary phospholipids.

The correlation between the secretion of biliary phospholipid (PL) and bile acid suggests a regulatory effect of bile acid on PL secretion. Bile acids may influence PL synthesis and/or the mobilization of a preformed PL pool. The objective of this study was to determine the contribution of these two sources to biliary PL, by using an experimental protocol in which dehydrocholic acid (DHCA) and cholic acid (CA) were infused to manipulate biliary PL secretion. In control rats, there was a steady state in bile flow. PL secretion and the biliary secretion of newly synthesized phosphatidylcholine (PC). The specific radioactivity of PC in bile was significantly higher than in plasma, microsomes and canalicular membranes. DHCA infusion decreased biliary PC secretion rate by 80%, and secretion returned to normal values at the transport maximum of CA. The specific radioactivity of biliary PC was decreased by 30% by DHCA infusion and reached normal values during CA infusion. There were no significant changes in the specific radioactivity of PC in plasma or cellular organelles during infusion of bile acids. These data indicate that: (1) newly synthesized PC contributes a small percentage to biliary PC; thus a preformed pool (microsomal and extrahepatic) is a major source of biliary PL; (2) the contribution of the extrahepatic pool to the biliary PL may be more important than the microsomal pool.     

Relationship between white spot syndrome virus and indicators of quality in Penaeus monodon postlarvae in Karnataka,India

White spot disease (WSD) is a viral disease of shrimp caused by white spot syndrome virus (WSSV). Stocking WSSV-infected seed has been implicated as a major risk factor for outbreaks of WSD. In addition, the quality of postlarvae batches has been proposed as a predictor for good crops. This paper describes the relationship between indicators of quality and WSSV in postlarvae (PL) of Penaeus monodon from Karnataka, India, over the period September 1999 to January 2000. Three outcome variables were considered: the WSSV status of the PL, as determined by PCR, and 2 subjective assessments of PL quality, namely the activity of the PL and the quality of the PL as determined by research assistants and farmers, respectively. Of the 73 batches of PL, 49.3% from a random sample of farms tested positive for WSSV. After adjusting for confounding, stocking earlier in the growing season and duration of transportation were the main risk factors for the presence of WSSV. The quality assessed by farmers and the PL activity assessed by research assistants showed only fair agreement (kappa 0.252) reaffirming the subjective nature of such techniques. The only variables consistently associated with either assessment of quality in univariate analysis were PL length, number per bag and salinity of the water in the delivery bags. After adjusting for confounding, no single variable was consistently associated with PL quality and activity. The research assistants' assessment of PL activity was also associated with the hatchery and a brown-orange hepatopancreas in univariate analysis. After adjusting for confounding, a brown-orange hepatopancreas was still significant and fitted into the model together with the salinity of the water in the PL bags. The farmers' assessment of quality was associated with PL length, date of stocking and duration of transportation in both univariate and multivariable analyses. There was no relationship between quality assessment and WSSV in PCR-positive PL.     

Anticoagulant activities of piperlonguminine in vitro and in vivo

Piperlonguminine (PL), an important component of Piper longum fruits, is known to exhibit anti-hyperlipidemic, antiplatelet and anti-melanogenic activities. Here, the anticoagulant activities of PL were examined by monitoring activatedpartial-thromboplastin-time (aPTT), prothrombin-time (PT), and the activities of thrombin and activated factor X (FXa). The effects of PL on the expressions of plasminogen activator inhibitor type 1 (PAI-1) and tissue-type plasminogen activator (t-PA) were also tested in tumor necrosis factor-α (TNF-α) activated HUVECs. The results showed that PL prolonged aPTT and PT significantly and inhibited the activities of thrombin and FXa. PL inhibited the generation of thrombin and FXa in HUVECs. In accordance with these anticoagulant activities, PL prolonged in vivo bleeding time and inhibited TNF-α induced PAI-1 production. Furthermore, PAI-1/t-PA ratio was significantly decreased by PL. Collectively, our results suggest that PL possesses antithrombotic activities and that the current study could provide bases for the development of new anticoagulant agents. [BMB Reports 2013; 46(10): 484-489]     

Fermentation characteristics and feeding value of ensiled poultry litter containing wheat straw,bagasse or sawdust

Poultry excreta substantially increased the crude protein (CP) content and the calcium and phosporus content of the base bedding materials. The crude fibre (CF) content of sawdust (52.3%) was higher than that of wheat straw (38.9%) and bagasse (30.2%). Dry matter digestibility in vitro (IVDMD) of wheat straw, bagasse and sawdust poultry litters (PL) was 65.4, 64.5 and 48.1%, respectively. Green sorghum fodder when ensiled alone or with 20% wheat straw PL, sawdust PL or bagasse PL on fresh basis contained 4.67, 7.80, 10.00 and 7.55% CP, respectively. Nitrogen-free extract (NFE) content of PL silages was lower than that of the control. Apart from wheat straw PL, all silages accumulated considerable amounts of lactic acid. The total volatile fatty acids (TVFA) concentrations were similar for all silages. The addition of PL caused an increase in the proportion of ammonia nitrogen. A feeding trial with crossbred adult male cattle revealed no significant difference in dry matter (DM), CP and ether extract (EE) digestibility of wheat straw and bagasse PL silages. The CF digestibility was similar for all the silages. Sawdust PL silage, however, was significantly lower (P < 0.05) in digestibility of DM, EE and NFE compared to other PL based silages. The DCP and TDN values for the control, wheat straw, bagasse and sawdust PL silages were 2.0, 60.1; 4.3, 45.3; 6.1, 50.3 and 2.9, 41.9 kg/100 kg DM, respectively.     

Behavioural and physiological mechanisms of polarized light sensitivity in birds

Polarized light (PL) sensitivity is relatively well studied in a large number of invertebrates and some fish species, but in most other vertebrate classes, including birds, the behavioural and physiological mechanism of PL sensitivity remains one of the big mysteries in sensory biology. Many organisms use the skylight polarization pattern as part of a sun compass for orientation, navigation and in spatial orientation tasks. In birds, the available evidence for an involvement of the skylight polarization pattern in sun-compass orientation is very weak. Instead, cue-conflict and cue-calibration experiments have shown that the skylight polarization pattern near the horizon at sunrise and sunset provides birds with a seasonally and latitudinally independent compass calibration reference. Despite convincing evidence that birds use PL cues for orientation, direct experimental evidence for PL sensitivity is still lacking. Avian double cones have been proposed as putative PL receptors, but detailed anatomical and physiological evidence will be needed to conclusively describe the avian PL receptor. Intriguing parallels between the functional and physiological properties of PL reception and light-dependent magnetoreception could point to a common receptor system.     

Biochemical and functional evidence that an MT3 supertypic determinant defined by a monoclonal antibody is carried on the DR molecule on HLA-DR7 cell lines

A cytotoxic monoclonal antibody, PL3, was produced by immunizing mice with a cell line homozygous for the HLA class II antigenic specificity DR7. The serologic specificity of PL3 was completely concordant with the MT3 supertypic specificity, which is tightly associated with HLA-DR4, -DR7, and -DRw9. This was confirmed by the finding that F(ab')2 fragments of PL3 blocked the cytotoxicity of anti-MT3 alloantisera. Although PL3 bound to each of the MT3-positive cell lines, it showed significantly weaker binding to HLA-DR4 and -DRw9 cells relative to -DR7 cells, both in titration and in quantitative absorption assays. This differential pattern of binding was not found for the polyclonal MT3 alloantisera, suggesting that the PL3 determinant may be one of several closely related determinants that comprise the MT3 allospecificity. To identify which of the subpopulations of class II molecules carry the PL3 determinant, several approaches have been used. F(ab')2 fragments of PL3 which block the anti-MT3 alloantisera were also tested with anti-MB2 and anti-DR7 sera. Binding of the PL3 F(ab')2 fragments to DR7 homozygous target cells had no effect on the anti-MB2 sera, but significantly enhanced the cytotoxic reactivity of some anti-DR7 sera. This finding suggested that the PL3 determinant is distinct from the DR7 determinant, but is carried on the same molecule. PL3 was also used in blocking studies with allocytotoxic T cell clones which only recognize DR7-positive cell lines. Binding of PL3 to the DR7-positive target cells was found to completely inhibit these T cell clones. Complete blocking was also found with a monoclonal antibody, PL8, which recognizes a monomorphic determinant found on the DR subpopulation of class II molecules. This finding suggested that the PL3 determinant is carried on the same molecule that carries these T cell-defined DR7 allodeterminants. In biochemical studies with DR7-positive cell lines, PL3 and PL8 were found to immunoprecipitate the same subpopulation of class II molecules recognized by other DR-specific antibodies, SG157 and TAL-1B5. Two-dimensional gel analysis demonstrated that the pattern of alpha- and beta-chains immunoprecipitated by PL3, PL8, and TAL-1B5 were identical. In sequential immunoprecipitation studies, both PL3 and TAL-1B5 were capable of removing the same DR subpopulation of molecules recognized by PL3, PL8, TAL-1B5, or SG157 while leaving the additional class II molecules (DS) recognized by SG171 on DR7 cells.(ABSTRACT TRUNCATED AT 400 WORDS)     

Specification and development of the pars intercerebralis and pars lateralis, neuroendocrine command centers in the Drosophila brain

The central neuroendocrine system in the Drosophila brain includes two centers, the pars intercerebralis (PI) and pars lateralis (PL). The PI and PL contain neurosecretory cells (NSCs) which project their axons to the ring gland, a complex of peripheral endocrine glands flanking the aorta. We present here a developmental and genetic study of the PI and PL. The PI and PL are derived from adjacent neurectodermal placodes in the dorso-medial head. The placodes invaginate during late embryogenesis and become attached to the brain primordium. The PI placode and its derivatives express the homeobox gene Dchx1 and can be followed until the late pupal stage. NSCs labeled by the expression of Drosophila insulin-like peptide (Dilp), FMRF, and myomodulin form part of the Dchx1 expressing PI domain. NSCs of the PL can be followed throughout development by their expression of the adhesion molecule FasII. Decapentaplegic (Dpp), secreted along the dorsal midline of the early embryo, inhibits the formation of the PI and PL placodes; loss of the signal results in an unpaired, enlarged placodeal ectoderm. The other early activated signaling pathway, EGFR, is positively required for the maintenance of the PI placode. Of the dorso-medially expressed head gap genes, only tailless (tll) is required for the specification of the PI. Absence of the corpora cardiaca, the endocrine gland innervated by neurosecretory cells of the PI and PL, does not affect the formation of the PI/PL, indicating that inductive stimuli from their target tissue are not essential for early PI/PL development.