Morphological and ultrastructural characteristics of symbiotic bacteria colonizing the surface of the helminth Triaenophorus nodulosus and the intestine of pike Esox lucius

The microflora inhabiting the intestinal mucosa of the pike and the tegument surface of the intestinal parasite Triaenophorus nodulosus is investigated. By means of electron microscopy, the ultrastructural features of bacteria and pattern of their interaction with the colonized surfaces are estimated. Specific distribution of microorganisms belonging to different morphotypes and subdivided into subpopulations on the colonized surfaces is found. Predominance of gram-negative bacteria in all studied microbiocenoses and abundance of nanobacteria in the “superficial” subpopulations are observed. The bacteria of “a deep population” associated with the basal parts of microtrichiae and microvilli are described. It is concluded that the helminthes, the fish parasites possess the normal microflora characterized by specific composition, by ultrastructural features of cells, and by patterns of interaction with the helminth surface. The obtained data characterize the mechanisms of symbiotic interaction of prokaryotes and eukaryotes in the system parasite-host-symbiotic microflora.     

Promotive effect of 5-aminolevulinic acid on chlorophyll,antioxidative enzymes and photosynthesis of Pakchoi (<Emphasis Type="Italic">Brassica campestris</Emphasis> ssp<Emphasis Type="Italic">.</Emphasis><Emphasis Type="Italic">chinensis</Emphasis> var. communis Tsen et Lee)

The objective of this article is to study the effect of 5-aminolevulinic acid (ALA) and enhanced chlorophyll content, antioxidative enzymes and photosynthesis rate by foliar application of ALA. We evaluated three concentrations (control-distilled water, T1-50 mg l⁻¹, T2-150 mg l⁻¹, T3-250 mg l⁻¹) of ALA and seven cultivars, “Sanchidaye” (Sa-1), “Lichuandasuomian” (Li-1), “Aijiaohuang” (Ai-1), “Qingyou” No. 4 (Qi-1), “Aikang” No. 5 (Ak-1), “Hanxiao” (Ha-1) and “Shulv” (Sl-1). “Ak-1” showed strongest response of POD (peroxidase) enzyme activity (0.4 U g⁻¹ min⁻¹) in 250 mg l⁻¹ ALA solution. The highest CAT (catalase) activity (0.8 U g⁻¹ min⁻¹) after administration of 250 mg l⁻¹ ALA was observed in “Li-1”. Meanwhile, highest (1.42 mg l⁻¹) total chlorophyll content was also observed in “Ak-1”, when leaves were treated in 50 mg l⁻¹ ALA, “Li-1” and “Ai-1” showed strongest response of specific activity of superoxide dismutase (SOD) in 50 mg l⁻¹ and 50 mg l⁻¹ ALA. Two hundred and fifty milligram per milliliter of ALA-treatment significantly improved the net photosynthetic rate.     

Temperature and irradiance impacts on the growth,pigmentation and photosystem II quantum yields of <Emphasis Type="Italic">Haematococcus pluvialis</Emphasis> (Chlorophyceae)

The microalga Haematococcus pluvialis Flotow has been the subject of a number of studies concerned with maximizing astaxanthin production for use in animal feeds and for human consumption. Several of these studies have specifically attempted to ascertain the optimal temperature and irradiance combination for growth of H. pluvialis, but there has been a great deal of disagreement between laboratories. “Ideal” levels of temperature and irradiance have been reported to range from 14 to 28°C and 30 to 200 μmol photons m⁻² s⁻¹. The objective of the present study was to simultaneously explore temperature and irradiance effects for a single strain of H. pluvialis (UTEX 2505) across an experimental region that encompassed the reported “optimal” combinations of these factors for multiple strains. To this end, a two-dimensional experimental design based on response surface methodology (RSM) was created. Maximum growth rates for UTEX 2505 were achieved at 27°C and 260 μmol photons m⁻² s⁻¹, while maximum quantum yield for stable charge separation at PSII (F_v/F_m) was achieved at 27°C and 80 μmol photons m⁻² s⁻¹. Maximum pigment concentrations correlated closely with maximum F_v/F_m. Numeric optimization of growth rate and F_v/F_m produced an optimal combination of 27°C and 250 μmol photons m⁻² s⁻¹. Polynomial models of the various response surfaces were validated with multiple points and were found to be very useful for predicting several H. pluvialis UTEX 2505 responses across the entire two-dimensional experimental design space.     

Tunable Assembly of Peptide-coated Gold Nanoparticles

The interaction between peptides and gold surfaces has increasingly been of interest for bionanotechnology applications. To more fully understand how to control such interactions, we have studied the optical properties of peptide-modified gold nanoparticles as a function of peptide composition, pH of the surrounding medium, and peptide concentration. We show using localized surface plasmon resonance, transmission electron microscopy, and surface-enhanced Raman scattering (SERS) that selected “gold-binding peptides” (GBPs), similar to those isolated for binding to gold films using yeast display, can bind to gold nanoparticles at a variety of pHs. Peptide modifications of nanoparticles can lead to irreversible particle aggregation when the pH of the solution is kept below the isoelectric point (pI) of the peptide. However, at pHs above the peptide’s pI, particles remain stable in solution, and peptides remain bound to the particles possibly through amine coordination of gold. Additionally, we demonstrate the potential in using SERS for the direct detection of GBPs on gold-silica nanoshells, eliminating the need for indirect labeling methods.     

<Emphasis Type="Italic">Escherichia coli,Pseudomonas aeruginosa</Emphasis>, and<Emphasis Type="Italic"> Staphylococcus aureus</Emphasis> Attachment Patterns on Glass Surfaces with Nanoscale Roughness

Attachment tendencies of Escherichia coli K12, Pseudomonas aeruginosa ATCC 9027, and Staphylococcus aureus CIP 68.5 onto glass surfaces of different degrees of nanometer-scale roughness have been studied. Contact-angle and surface-charge measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM) were employed to characterize substrata and bacterial surfaces. Modification of the glass surface resulted in nanometer-scale changes in the surface topography, whereas the physicochemical characteristics of the surfaces remained almost constant. AFM analysis indicated that the overall surface roughness parameters were reduced by 60–70%. SEM, CLSM, and AFM analysis clearly demonstrates that although E. coli, P. aeruginosa and S. aureus present significantly different patterns of attachment, all of the species exhibited a greater propensity for adhesion to the “nano-smooth” surface. The bacteria responded to the surface modification with a remarkable change in cellular metabolic activity, as shown by the characteristic cell morphologies, production of extracellular polymeric substances, and an increase in the number of bacterial cells undergoing attachment.     

Iota-carrageenan from a newly farmed, rare variety of eucheumoid seaweed—“endong”

A seaweed with the local name “endong” is a rare eucheumoid variety that has recently been farmed in Tawi-Tawi, southern Philippines. Local farmers describe it as “eel-like” because of its long, slender and smooth thalli. Being somewhat similar in appearance to the dominantly farmed seaweed “tambalang” (Kappaphycus alvarezii var. tambalangii), farmers mix their harvests of “endong” with those of “tambalang”. We analyzed the hydrocolloid extract from “endong” using spectroscopic and chemical techniques. The extract’s infrared and nuclear magnetic resonance (¹H and ¹³C) spectra, and sulfate and 3,6-anhydrogalactose contents revealed carrageenan of the iota-type, similar to extracts from another farmed species, Eucheuma denticulatum. This result implies that “endong” carrageenan exhibits physico-chemical properties different from those of kappa-carrageenan of “tambalang”. The findings of this study are of significance to the seaweed industry, as carrageenan quality problems could potentially arise from a mixed harvest. Seaweed farmers are advised to separate their harvests of “endong” and “tambalang”. Presented at the 19th International Seaweed Symposium, Kobe, Japan     

Starch-bound 2S proteins and kernel texture in einkorn, <Emphasis Type="Italic">Triticum</Emphasis> <Emphasis Type="Italic">monococcum</Emphasis> ssp <Emphasis Type="Italic">monococcum</Emphasis>

The starch granule proteins from 113 einkorn wheat (Triticum monococcum ssp monococcum) accessions were analyzed by acidic, polyacrylamide gel electrophoresis (A-PAGE), and two-dimensional A-PAGE x SDS-PAGE. All accessions were confirmed to contain equal amounts of two polypeptide chains corresponding to puroindoline B (Pin-B), as well as a prominent component plus a faint band corresponding to puroindoline A (Pin-A). When compared with soft-textured common wheat, “monococcum” accessions showed an increase of 3.2- and 2.7-fold in Pin-A and Pin-B levels on the starch granules, respectively. In addition, all accessions contained a novel component of the 2S super-family of seed proteins named Einkorn Trypsin Inhibitor (ETI), which was found to be encoded as a pre-protein 148 residues long. Wild-type ETI encoded by allele Eti-A ^m 1a and “valine-type” ETI encoded by allele Eti-A ^m 1b, which occurred in 107 and six einkorn accessions, respectively, were found to accumulate on starch granules as a mature protein of 121 amino acids with a hydrophobic central domain. The einkorn accessions exhibited an average SKCS index as low as −2.05 ± 11.4, which is typical of extra-soft kernels. The total surface area of starch granules in “monococcum” wheat, as determined by visual assessments in counting chambers, was estimated at 764 mm²/mg of starch, and was about 1.5 times higher than that for common wheat. The results are discussed in relation to the identification of factors that cause the extra-soft texture of einkorn kernels.     

Distribution of abundance, biomass, production and productivity of macrozoobenthos in the sub-Antarctic Magellan Province (South America)

Distribution of abundance, biomass, productivity and production of macrozoobenthos was investigated in four study areas in the Magellan region (South Patagonian Ice-Field, Strait of Magellan, Beagle Channel, Continental Shelf). Using a Reineck box corer and a multibox corer, a total of 277 quantitative benthos samples were taken at 78 stations in water depths between 8 and 1139 m during the Joint Chilean-German-Italian Magellan “Victor-Hensen Campaign” in 1994, the “Polarstern” expedition ANT XIII/4 in 1996 and the Chilean expeditions “Cimar Fiordo II + III” in 1996 and 1997, respectively, on board RV “Vidal Gormaz”. Mean abundance in the South Patagonian Ice-Field was significantly lower than in the Strait of Magellan and the Beagle Channel. Biomass and abundance decreased clearly with depth (20–300 m to 700–1500 m: 3.9 gC m⁻² to 0.6 gC m⁻²; 2832 ind. m⁻² to 569 ind. m⁻²). Average abundance, biomass and production of the whole Magellan region are lower (2318 ind. m⁻², 3.2 gC m⁻², 0.62 gC m⁻² year⁻¹) than in the high Antarctic Weddell Sea. In the Magellan region, macrozoobenthos composition of abundance is mainly dominated by polychaetes (56%), followed by arthropods (16%), echinoderms (10%) and molluscs (11%). Comparisons of our present results with those of high Antarctic areas make it clear that the Magellan region has a transitional character. Accepted: 21 December 1998     

Hydrochemistry and microbialites of the alkaline crater lake Alchichica,Mexico

The structure, mineralogy, and accretion processes of the modern and subfossil cyanobacterial microbialites from the alkaline crater lake Alchichica (Puebla, Mexico) were studied, along the lake’s bathymetry and hydrochemistry. The recent lowering of the lake level had exposed microbialitic carbonate mounds and crusts, which emerged up to 2 m above the water surface, while accreting cyanobacterial microbialites were present down to a depth of ~15 m. Morphological and molecular analysis found that the living cyanobacterial mats were composed of diverse filamentous and coccoid cyanobacteria (Nostocales, Chroococcales, Oscillatoriales, and Pleurocapsales). The emerged subfossil microbialites comprised two generations: “white” (domes and crusts composed mainly of hydromagnesite with an admixture of huntite and calcite, ²³⁸U/²³⁰Th age of ~2.8 ka BP), and “brown” (chimneys, columns and laminated crusts composed of aragonite with an admixture of Mg-calcite, ²³⁸U/²³⁰Th age of ~1.1 ka BP). The significant age, structural, mineralogical, and isotopic differences suggest that the two generations were formed in different environmental conditions: the “white” during a dry period, and the “brown” in wet climate associated with high water level and intense inflow of ground water, which lowered the Mg/Ca ratio resulting in formation of aragonite instead of hydromagnesite. The hydromagnesite, replacing the primary aragonite precipitated in the living cyanobacterial biofilm, frequently undergoes silicification, which obliterates both the primary structure of the carbonate and the enclosed remains of cyanobacterial microbiota. This process helps to explain the abundant formation of dolomites and cherts in an allegedly highly alkaline Early Precambrian ocean. Thus, Lake Alchichica represents a modern alkaline environment where biosedimentary structures resembling Precambrian deposits are generated.     

Low voltage-activated Ca2+ conductances in thalamic neurons

Low voltage-activated (LVA) Ca²⁺ conductances were characterized in the neurons of the associative laterodorsal (LD) thalamic nucleus in rat brain slices and in enzymatically isolated thalamic units using electrophysiological techniques. Voltage dependence, kinetics of inactivation, pharmacology, and selectivity of the LVA current in the thalamic neurons from animals older than 14 postnatal days were consistent with the existence of two, “fast” and “slow,” subtypes of LVA Ca²⁺ channels. “Slow” LVA current in enzymatically isolated thalamic neurons was much less prominent, compared with that in slice neurons, suggesting that respective channels are predominatly located on the distal dendrites. “Fast” Ca²⁺ channels were sensitive to nifedipine (K _d−2.6 μM) and La³⁺ (K _d−1.0 mM), whereas “slow” Ca²⁺ channels were sensitive to Ni²⁺ (25 μM). Selectivity of the “fast” Ca²⁺ channels was similar to that found for the LVA Ca²⁺ channels in other preparations (I _Ca:I _Sr:I _Ba−1.0: 1.23: 0.94), while selectivity of the “slow” Ca²⁺ channels more resembled selectivity of the HVA Ca²⁺ channels (I _Ca:I _Sr:I _Ba−1.0: 2.5: 3.4).     

Influence of ovule perforation,plant growth regulators,andl-glutamine on in vitro growth of immature peach embryos

Summary Ovule perforation technique and media components (plant growth regulators andl-glutamine) were tested on in vitro growth of immature (<3 mm) embryos of “Springcrest” and “Earligrande” peaches. Ovule perforation was 2 to 4 times more effective in promoting embryo growth than leaving ovules intact.l-Glutamine (400 mg·liter⁻¹) promoted an increase in growth but could not be used with indole-acetic acid plus kinetin because an antagonistic effect on embryo growth occurred. The use of these exogenous plant growth regulators did not increase embryo growth over in vivo growth.     

Visualization of mitochondrial coupling factor F1(ATPase) by freeze-drying

It is known that the negatively stained preparations of inner mitochondrial membrane display characteristic ∼9 nmF ₁ (ATPase) knobs projecting from the matrix surface. Freeze-etch studies have reported the absence of such knobs from the “etched” surface of the inner mitochondrial membranes. We have demonstrated their presence on the surface of SMP (submitochondrial particles) prepared by freeze-drying for transmission electron microscopy. This identification has been substantiated by comparison with the freeze-dried TU particles (trypsin-urea treated SMP) that are devoid ofF ₁ (ATPase). It has been suggested that a layer of water molecules is strongly adsorbed to the surface of SMP and does not sublime during normal freeze-“etching.”     

The female genitalic morphology of “micronetine” spiders (Araneae,Linyphiidae)

Current knowledge of “micronetine” female genitalia is almost exclusively based on transmitted light microscopy data. As such, our understanding of the epigynal anatomy is incomplete and somewhat misleading, to the extent that it hinders comparative studies of linyphiid diversity. We used scanning electronic microscopy (SEM) to study the complex epigynal morphology of “micronetine” spiders. Enzymatic digestion of soft tissues allowed us to examine the internal chitinized structures in detail using SEM. A taxonomic sample of nine species was selected to represent the morphological genitalic diversity of female “micronetines” (including one member of the Erigoninae clade). Results reveal that the epigynum consists of a pair of grooves formed by integument folds (copulatory and fertilization grooves). The protruding epigynal region is divided into a ventral and a dorsal plate by the grooves; both plates can be modified to form an epigynal cavity and/or a scape. Our observations confirm the widespread occurrence of epigynal grooves, rather than ducts, in “micronetines”. Epigynal grooves seem to be common in linyphioids and other spider groups.     

Atmospheric culturable bacteria associated with meteorological conditions at a summer-time site in the mid-Willamette Valley,Oregon

A set of simultaneously collected quantitative measurements of 12 meteorological and 6 culturable atmospheric bacterial (CAB) variables was made over a grass seed field during several early, mid, and late summer days. The observation site was located between the Cascade and Coastal Mountain Ranges near Corvallis in the Willamette Valley, Oregon. Principal component analysis identified those meteorological variables that had the highest loadings in six eigenvectors that account for 95.9% of variation in the data factors, i.e., temperature @ 6.3 m above ground level (AGL), wind velocity @ 10.0 m AGL, wind velocity difference @ 1.7–10.0 m, barometric pressure, wind direction standard deviation, and wind direction. When these variables were used in a cluster analysis, they formed three statistically distinct meteorological variable clusters with means at ca. “midnight”, ca. “midday”, and ca. “evening.” The highest mean density of CAB (i.e., 153.4 ± 162.5 CFU/m³) was associated with the “midday” meteorological Cluster-1 that had warm, dry “gentle breezes” from the southeast, in the relatively bacteria loaded Willamette Valley air. The lowest mean density of CAB (i.e., 35.5 ± 24.1 CFU/m³) was associated with meteorological Cluster-3 in the late afternoon and “evening” occurring during the hottest and driest part of the day with “fresh breezes” coming from the north northwest in air off the Pacific Ocean. Finally, the last cluster, Cluster-2 occurred about midnight and had an intermediate density of CAB (74.2 ± 76.2 CFU/m³) in “light air” coming from the northwest, perhaps off the Pacific Ocean. The CAB associated with each of the three meteorological clusters was only partially statistically distinct. Partially because the CAB in both the Pacific Ocean derived air masses of the “evening” Cluster-3 and “midnight” Cluster-2 were not statically separable, though both were statistically separable from the midday, Willamette Valley derived Cluster-1. Further indicating their common source, both Pacific Ocean derived air masses had very similar percentages of pigmented bacteria, which were dissimilar to the pigmented bacterial population density in the Willamette Valley air masses. In short, it is speculated that “midnight” atmosphere may simply contain the settling concentrated residual bacterial particles in the abated fresh Pacific Ocean breezes after sundown. It is clearly shown that with the methods employed, it is possible to associate the uniqueness of the quantity, and to a lesser extent the quality, of the CAB population with the atmospheric conditions reported herein. From this project comes speculation that the strategies relating the quasi-conservative bacterial populations associated with distinct but nonconservative air mass properties can help to better understand more of the bacterial dynamics found in such situations. And to a further extent, molecular biological methods could be applied to identify bacterial taxa in specific air masses.     

Palaeoenvironmental significance of lacustrine stromatolites of the Arnstadt Formation (“Steinmergelkeuper”, Upper Triassic, N-Germany)

Lacustrine stromatolites of the Norian Arnstadt Formation (“Steinmergelkeuper”) occur on top of asymmetric flooding–evaporation cycles of a closed lake basin. They have been investigated with regard to associated lithofacies and biota, microfabric and stable carbon and oxygen isotopes. The stromatolites of the “Middle Grey Series” are brecciated and reworked by a flooding event of a subsequent lake cycle. They comprise agglutinated stromatolites rich in fish scales as well as skeletal stromatolites composed of a rhythmically grown dendroid micropeloidal framework. The latter are characterized by a shift towards positive δ¹³C values relative to the associated lake carbonates. This points to an effective photosynthesis in biofilm calcification at low concentrations in dissolved inorganic carbon (DIC) in a perennial fresh to brackish water lake. The stromatolites of the “Upper Red Series” occur on top of perennial lake cycles intercalated between playa lake deposits. The fine-grained stromatolites are poor in microfabric characteristics but show a significant covariation of δ¹⁸O and δ¹³C. This points to evaporation/degassing acting as driving mechanism in biofilm calcification. The lack of biotic effects on carbon isotope fractionation may reflect high concentrations in dissolved inorganic carbon. Skeletal oncoids, which occur as allochthonous components within an intraformational lag deposit of the “Upper Red Series”, are composed of cyanobacterial tubes and probably represent lowest saline lakes with only poor DIC buffering. Stable isotope signatures in conjunction with stromatolite microfabric analyses may be used as a proxy of DIC concentrations in ancient closed lakes.     

Mating behavior of the rock catfish, Silurus lithophilus

The mating behavior of the rock catfish Silurus lithophilus (Siluriformes: Siluridae), a species endemic to the Lake Biwa system, was observed from May to July in 1989–1994 along the rocky shore of the lake's outlet, the Seta River. The mating behavior of S. lithophilus involved a certain behavioral sequence: “chasing,”“clinging,” and “enfolding” while “squeezing” by the male; and “circling” by the spawned pair. The mating behavior of this species was basically similar to that of S. biwaensis, but greatly different from that of S. asotus, which spawns in running water (in ditches). The mating behavior of S. lithophilus (and S. biwaensis) might have developed as an adaptation to lentic environments such as the shores of the large river or the lake. Received: October 25, 2000 / Revised: February 25, 2001 / Accepted: March 8, 2001     

State of the immune system after seven-day “dry” immersion in human

Subpopulations of lymphocytes, activation potency of T, B, and NK cells, and cytokine production by immunocompetent cells of peripheral blood were studied in five volunteers subjected to seven-day “dry” immersion. Our results show that staying of a man under conditions of “dry” immersion resulted in a detrimental shift of some indices of the immune and cytokine systems. We found substantial individual differences in the response of the immune system of the subjects to seven-day immersion. These differences indicate individual susceptibility to development of immune reactivity to conditions of changing gravity.     

SERS quantitative detection of trace human chorionic gonadotropin using a label‐free Victoria blue B as probe in the aggregated immunonanogold sol substrate

Nanogold particles (NG) were modified by anti‐rabbit antibody (RAb) against human chorionic gonadotropin to obtain an immunonanogold probe (ING). In pH 7.0 Na₂HPO₄‐citrate buffer solution containing KCl, ING probes formed large aggregates in which Victoria blue B (VBB) molecules were adsorbed on the surface and which exhibited strong surface‐enhanced Raman scattering (SERS) at a peak of 1612 cm^–1. After addition of human chorionic gonadotropin (hCG) an immune reaction with the ING probe occurred to form dispersive ING–hCG complexes with non‐SERS activity that led to a decreased SERS peak at 1612 cm^–1. The decreased SERS intensity was linear to the concentration of hCG over 2.4–73.2 ng/mL. The ING reaction was studied in detail by SERS, scanning electron microscope (SEM), resonance Rayleigh scattering (RRS), surface plasmon resonance (SPR) absorption and laser scattering techniques. SERS quenching was observed and discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

New species of Pogonophryne (Pisces, Artedidraconidae) from the Bellingshausen Sea, Antarctica

A new species of notothenioid fish, Pogonophryne bellingshausenensis n. sp., is described from the Bellingshausen Sea, Antarctica. The new species belongs to the dorsally-spotted “mentella” group of the genus and is characterized by having a short (about 13% SL) mental barbel with a short (about 16% of barbel length), narrow (barely wider than the stalk), and relatively inconspicuous terminal expansion composed of short, irregular, fingerlike processes. Compared to most other dorsally-spotted species of Pogonophryne (“barsukovi”, “marmorata”, and “mentella” groups), P. bellingshausenensis has a relatively wide (about 7% SL) interorbital region. An unspotted patch on the median dorsal surface of the head, posterior to the posttemporal ridges and anterior to the first dorsal fin, has not been observed previously in any dorsally-spotted species. The holotype was collected at 1,947 m, one of the deepest records for any species of Pogonophryne. A revised key to the ten species of the “mentella” group of Pogonophryne is also provided.     

In silico QSAR studies of anilinoquinolines as EGFR inhibitors

Members of the epidermal growth factor receptor (EGFR) family of proteins are frequently overactive in solid tumors. A relatively new therapeutic approach to inhibit the kinase activity is the use of ATP-competitive small molecules. In silico techniques were employed to identify the key interactions between inhibitors and their protein receptors. A series of EGFR inhibitory anilinoquinolines was studied within the framework of hologram quantitative structure activity relationship (HQSAR), density functional theory (DFT)-based QSAR, and three-dimensional (3D) QSAR (CoMFA/CoMSIA). The HQSAR analysis implied that substitutions at certain sites on the inhibitors play an important role in EGFR inhibition. DFT-based QSAR results suggested that steric and electronic interactions contributed significantly to the activity. Ligand-based 3D-QSAR and receptor-guided 3D-QSAR analyses such as CoMFA and CoMSIA techniques were carried out, and the results corroborated the previous two approaches. The 3D QSAR models indicated that steric and hydrophobic interactions are dominant, and that substitution patterns are an important factor in determining activity. Molecular docking was helpful in identifying a bioactive conformer as well as a plausible binding mode. The docked geometry-based CoMFA model with steric and electrostatic fields effect gave q ² = 0.66, r ² = = 0.94 with r ² _predictive = 0.72. Similarly, CoMSIA with hydrophobic field gave q ² = 0.59, r ² = 0.85 with r ² _predictive = 0.63. Bulky groups around site 3 of ring “C”, and hydrophilic and bulky groups at position 6 of ring “A” are desirable, with a hydrophobic and electron-donating group at site 7 of ring “A” being helpful. Accordingly, potential EGFR inhibitors may be designed by modification of known inhibitors.