Spatiotemporal pattern of glucose in a microfluidic device depend on the porosity and permeability of the medium: A finite element study.

BACKGROUND: Glucose plays an important role as a source of nutrients and influence cellular processes such as differentiation, proliferation and migration. In vitro models based on microfluidic devices represent an alternative to study several biological processes in a more reproducible and controllable method compared to in vivo models. Glucose concentration across a microfluidic chip and its behavior in experimental conditions is not completely understood. OBJECTIVE: This paper investigated the spatiotemporal distribution of glucose across the hydrogel inside a microfluidic chip. The influence of different parameters, boundary and initial conditions of experiments on glucose concentration was studied. METHODS: A finite element model using a two dimensional geometry was developed. With this model, patterns of glucose concentration were investigated for different combinations of flow rate of culture medium, permeability and porosity of the medium. Patterns were also studied for two hydrogels made of collagen type I and fibrin with different initial and boundary conditions for pressure and glucose concentration. RESULTS: Porosity influenced significantly on the chemical gradients generated when interstitial fluid flow was null or neglectable. A difference in concentration lower than 15% was obtained at the input of microchamber and after 90 min, when porosity changed from 0.5 to 0.99. In addition, no significant effects of modifications in permeability were observed. Regarding the collagen and fibrin matrices, in the presence of a pressure gradient of 40 Pa, the permeability significantly influenced on the concentration gradients generated. CONCLUSIONS: Porosity influences importantly on patterns when diffusion is the main transport mechanism. Permeability is the most influencing parameter when a fluid flow is present. Common insertion rates of culture medium does not significantly modify the patterns of glucose inside the chips. Thus, new experiments must consider the impact of such parameters on the distribution and the time span that nutrients occupy the medium. To better contribute with experimental trials, other studies involving cell-cell and cell-extracellular matrix interactions, and different chip geometries should be developed. The results of the present work could assist to develop specific systems for experimentation, to design new experiments and to improve the analysis of the obtained results.

A new species of gall midge associated with Diplopterys pubipetala (A.Juss.) Anderson and Davis (Malpighiaceae) from Altinópolis, São Paulo, Brazil.

Clinodiplosis bellum sp. nov. associated with Diplopterys pubipetala (A.Juss.) Anderson and Davis (Malpighiaceae) from Brazil are described. This is the first species of Clinodiplosis described to State of São Paulo and the first formal description of Diplopterys pubipetala (Malpighiaceae) as host plant of Cecidomyiidae species. Description and illustration of the Clinodiplosis bellum sp. nov. (Diptera: Cecidomyiidae) are given.

Galls and gall makers in plants from the Pé-de-Gigante Cerrado Reserve, Santa Rita do Passa Quatro, SP, Brazil.

Thirty-six morphologically different types of galls were obtained in leaves, leaflets, veins, petioles, stems, tendrils and flower buds from twenty-five species of plants in the Pé-de-Gigante Reserve, municipality of Santa Rita do Passa Quatro, state of São Paulo, Brazil. The host plant species belong to the closely related families Anacardiaceae, Annonaceae, Asteraceae, Bignoniaceae, Caryocaraceae, Erythroxylaceae, Fabaceae, Malpighiaceae, Melastomataceae, Myrtaceae, Ochnaceae, Polygalaceae, Sapindaceae, Sapotaceae, and Smilacaceae. The most common gall makers included Cecidomyiidae (Diptera), Pteromalidae (Hymenoptera) and Diaspididae (Sternorrhyncha-Hemiptera). This is the first report of galls found in the following plant genera: Gochnatia (Asteraceae), Distictela (Bignoniaceae), Banisteriopsis (Malpighiaceae), Ouratea (Ochnaceae), and Bredemeyera (Polygalaceae). The results of this work contribute to the body of knowledge about the relationship among host plants, gall makers, and the gall morphology of Pé-de-Gigante Cerrado Reserve.

Galls and gall makers in plants from the Pé-de-Gigante Cerrado Reserve, Santa Rita do Passa Quatro, SP, Brazil

Trinta e seis diferentes tipos morfológicos de galhas foram obtidos em folhas, foliólulos, nervuras, pecíolos, ramos e inflorescências de vinte e cinco espécies de plantas na Reserva de Cerrado Pé-de-Gigante, Município de Santa Rita do Passa Quatro, SP, Brasil. As plantas hospedeiras pertencem às famílias: Anacardiaceae, Annonaceae, Asteraceae, Bignoniaceae, Caryocaraceae, Erythroxylaceae, Fabaceae, Malpighiaceae, Melastomataceae, Myrtaceae, Ochnaceae, Polygalaceae, Sapindaceae, Sapotaceae e Smilacaceae. Entre as famílias dos insetos galhadores foram observados Cecidomyiidae (Diptera), Pteromalidae (Hymenoptera) e Diaspididae (Sternorrhyncha-Hemiptera). Este é o primeiro relato da presença de galhas em plantas dos seguintes gêneros: Gochnatia (Asteraceae), Distictela (Bignoniaceae), Banisteriopsis (Malpighiaceae), Ouratea (Ochnaceae) e Bredemeyera (Polygalaceae). Os resultados deste trabalho contribuem para o aumento do conhecimento das relações entre plantas hospedeiras e galhadores e da morfologia das galhas da Reserva de Cerrado Pé-de-Gigante.

Occurrence and characterization of entomogen galls in plants from natural vegetation areas in Delfinópolis, MG, Brazil

In the present work we aimed to register the occurrence of galls, inductors, inquilines, and parasitoids in plants of three natural vegetation areas in Delfinópolis, MG, Brazil. Results obtained showed 22 types of galls collected from leaf, vein leaf, petioles, stem, and inflorescence of nineteen species belonging to fifteen distinct families. Concerning gall morphology, the following were collected: globoid, conicle, discoidal, fusiform, shell-shape, indefinite, and one substituition of an ovary by an immature. As principal inducers were found insects of the families Cecidomyiidae (Diptera), Psyllidae, and Diaspididae (Sternorrhyncha/Hemiptera). As parasitoids the most common are of the Chalcidoidea superfamily (Hymenoptera) and, as occasional inquilines, Polyxenidae (Diplopoda) and Psocodea (Psocoptera). The results of this study contribute to existing of knowledge host-plant diversity and gall-associated insects in rocky fields, cerrado, and gallery forests.

Occurrence and characterization of entomogen galls in plants from natural vegetation areas in Delfinópolis, MG, Brazil.

In the present work we aimed to register the occurrence of galls, inductors, inquilines, and parasitoids in plants of three natural vegetation areas in Delfinópolis, MG, Brazil. Results obtained showed 22 types of galls collected from leaf, vein leaf, petioles, stem, and inflorescence of nineteen species belonging to fifteen distinct families. Concerning gall morphology, the following were collected: globoid, conicle, discoidal, fusiform, shell-shape, indefinite, and one substituition of an ovary by an immature. As principal inducers were found insects of the families Cecidomyiidae (Diptera), Psyllidae, and Diaspididae (Sternorrhyncha/Hemiptera). As parasitoids the most common are of the Chalcidoidea superfamily (Hymenoptera) and, as occasional inquilines, Polyxenidae (Diplopoda) and Psocodea (Psocoptera). The results of this study contribute to existing of knowledge host-plant diversity and gall-associated insects in rocky fields, cerrado, and gallery forests.