Fábio Abdalla | UFSCar - Federal University of São Carlos (original) (raw)

Papers by Fábio Abdalla

Bombus presents a serious global decline of populations and even loss of species. This phenomenon... more Bombus presents a serious global decline of populations and even loss of species. This
phenomenon is complex and multifactorial: environmental degradation due to increasing
cultivation and grazing areas, indiscriminate use of agrochemicals, and a plethora of xenobiotics
daily discharged in the environment. We proposed that bees have an integrated cell
system, which ensures protection against chemical stressors up to a certain limit. Therefore,
this hypothesis was tested, exposing workers of Bombus morio to cadmium, a harmful
trace metal nowadays widespread in our society. The workers were kept in BOD (26°C, RH
70%, in the dark), fed ad libitum, and divided into a control group (n = 20) and an experimental
group (n = 20). For the first group, we offered 2 mL of distilled water; for the experimental
groups, 2mL of cadmium at 1 ppb. In relation to the control group, exposed bees showed
that their fat body and hemocytes responded in synchronization with pericardial cells in a
topographical and temporal cascade of events, where the fat body is the first barrier against
xenobiotics, followed by pericardial cells. The immune cells participate throughout the process.
To this system, we proposed the name of hepato-nephrocitic system (HNS), which
may explain many phenomena that remain unclear in similar research with Apis mellifera
and other species of bees, as shown in this paper. The bee’s HNS is a system of highly
responsive cells to toxicants, considered a novel parameter for the study of the ecology of
stress applied in environmental management.

Larvae of honeybee workers were exposed to the insecticide fipronil during the feeding phase. To ... more Larvae of honeybee workers were exposed to the insecticide fipronil during the feeding phase. To
evaluate the effect of fipronil in the post-embryonic development of africanized Apis mellifera,
bioassays of toxicity were done. The bioassays were performed by acute exposure applying 1μL of
distilled water for control (I) and for experiments: 0.5 ng a.i./µL of fipronil; 5 ng a.i./µL of fipronil
and 20 ng a.i./ µL of fipronil. Triplicates were performed for all treatments. The results showed that
the rate of anomalous pupae in exposed honeybees was statistically significant in relationship to
the control (p <0:03). The most frequent abnormalities were: high pigmentation on the proximal
and distal larval body and body malformation, such as absence of head and limbs. Pink eye pupa
and white eyed pupae presented malformations in their larval bodies, but with the eye developed.
It is assumed that the fat body is related to the high rate of anomalies, since this tissue has proteins
linked to the process of metamorphosis. Furthermore, the fat body may be participating in the
regulation of juvenile hormone during the process of metamorphosis, and consequently in the
release of ecdysteroid hormones that are involved in the change from larva to adult. The high rate
of abnormalities in the pupal stage of individuals exposed to fipronil raises concerns about the
impacts caused in the colonies of bees and population decline of pollinators.

CAMPUS DE SOROCABA ESTADO DE SÃO PAULO SOROCABA, 2014 UNIVERSIDADE FEDERAL DE SÃO CARLOS Campus d... more CAMPUS DE SOROCABA ESTADO DE SÃO PAULO SOROCABA, 2014 UNIVERSIDADE FEDERAL DE SÃO CARLOS Campus de Sorocaba Rodovia João Leme dos Santos, km 110, SP 264 -Itinga. Cx.Postal 3031-CEP 18052-780-Sorocaba -SP -Brasil Fone 0XX15-3229-6000 (PABX) Home page: http://www.ufscar.br 1. FUNÇÃO, ORGANIZAÇÃO E ESTRUTURA CELULAR (ESTA ATIVIDADE EQUIVALE A UMA AVALIÇÃO TEÓRICA COM PESO 1) Instruções FORMAR GRUPOS DE 5 PESSOAS

Physiology corresponds to a discipline that studies the relationship among functional processes t... more Physiology corresponds to a discipline that studies the relationship among functional processes that occur in different organic systems and how it results in homeostasis. The process of teaching-learning of this discipline presents great difficulties, since it requires integration of skills and previous knowledge of other general biology matters (such as cellular biology, biochemistry and biophysics). Consequently, several concepts require students to establish an inter-relation of these matters in order to comprehend and to build knowledge, as well as to apply what was studied. In addition, there is the aim of promoting a meaningful learning, in which the students build new concepts based on their prior knowledge. Moreover, some key concepts necessary to understand Physiology are very complex and occur in a sub-cellularlevel, making it difficult to be directly proved by theoretical traditional educational practices. Due to previous observations, professors face the challenge of reformulate their methodologies in order to able the students to build knowledge in this very
specific subject. Considering the worldwide diffusion and the easy access to new information and communication technologies, this research presents an alternative tool in a tentative of making Physiology teaching more dynamic, using graphical computing. Animations were built using a graphic software that illustrates macroand/or microscopic process that are difficult to visualize, and may be used as prior knowledge organizers. Three contents were chosen to develop animations, as follows: a) Strategies of osmoregulation developed by fresh water and sea water
teleost fish; b) Water flow through gills: count current and concurrent mechanisms; and, c) Membrane physiology: resting membrane potential, depolarization and repolarization. These animations were applied in the Comparative Animal Physiology
discipline at Universidade Federal de São Carlos, Sorocaba Campus, and theprofessor asked the students to write down their opinions regarding to the learning material. Besides that, this learning material was also presented to a small group of
students and later on there was an oral debate to verify the opinion about the animations. Finally, it was possible to observe points in the animations that need to be improved and also to point out positive aspects of applying this technology in undergraduate courses.

In an effort to establish this new educational point of view in our university, this paper deals ... more In an effort to establish this new educational point of view in our university, this paper deals with one of several efforts we fought every day to offer our students an education with quality. This paper presents several activities developed in the Bachelor's
Degree in Full Biological Sciences of UFSCar - Campus Sorocaba, in the discipline of Histology. Activities were employed in which the histology was grounded from the survey of alternative conceptions of students on the theme of Muscle Tissue and
construction of histology models. In this work, we dealt with the analysis of histological slides showing slices of organs, processes that were interrupted, and the difficulty in the abstraction of the whole organ, or notion of movement processes. During application
development, we employed the use of the conceptual map. This tool enhances the meaning of concepts, in which the basics are connected to the specifics in a way as the executor of the map hierarchy considers correct. The analysis of the perception of tridimensionality and bi-dimensionality of the students was made by observing drawings made by them, starting from both the vision for the bi-dimensional to tri-dimensional, as
from tri-dimensional to bi-dimensional, and schemes together with the degree of difficulty rated by the students. The analysis shows that there is indeed a barrier to imagine the three-dimensional figures through two-dimensional, however, the schemes made by the students expose a change in the interpretation of three dimensionality, by mixing the two and three-dimensional. It can be concluded that new methodologies require the teacher humility and adaptability, therefore, the control of activity belongs to
the learners.

Since the beginning of cartesian, or even before, the classical education includes binomials as t... more Since the beginning of cartesian, or even before, the classical education includes binomials as the only way to thing about phenomena, as "right or wrong", "true or false”, “good or bad." These concepts do not prepare the students for a society of constant change and inexactness. Human behavior, as well as much of natural phenomena, is not entirely logical. Additionally, our impressions and perceptions of things are not equal. Students undergo an education of certainty can not develop their skills and creative cognitive processes, becoming citizens unable to reflect and change their behavior. The behavioralflexibility is a vital factor not only to live, but to live well and to provide facilities to learn.
Students should comprehend the doubts as positive factors, essential for the construction of their knowledge. The teacher, into this context, is a mediator, being part of this process to support the students build meaningful and critical learning. In this way, the present investigation aimed to analyze the process of teaching and learning focused on various innovative teaching methodologies, based on several dynamic in Cell Biology and Histology, with first-year university students of Biological Sciences, among years 2007 to 2009, in the UFSCar, Campus Sorocaba. Through dynamics of teaching and learning that include the
cognitive steps of sincrese, analysis, synthesis and antithesis, we investigated the knowledge brought by high school students, trying to take some concepts out, which should required unlearning, and especially invite them to reflect on scientific knowledge critically, seeking for the whys by themselves, not waiting for the teacher to provide all the answers. In the first two
learning dynamics, materials were used kit of cell construction that enabled the enable the students to do models of two-dimensional cells, through their previous concepts brought of the last year of the high school. The third dynamic in which the Histology was the subject was used only with the students of licenciature, we investigated the concepts of common sense of the academic on the topics muscle and adipose tissues. Another activity developed were done simulating jury like, which initially consisted of a cycle of dramas where there was not a defendant, but controversial and contentious issues to be defended for groups of students. Later, this activity was changed to a round table, with the participation of experts of Physiology, Law and Bioethics. Finally, the last dynamic we used concept maps. The concepts maps were use at the beginning, middle and end of the discipline Histology on 2009
in both courses. The aim of this activity was analyzed learning process of the students along the semestry, as well as the teacher praxis. The environment of the dynamics promoted the interaction, integration, reconciliation and differentiation of the concepts of the disciplines, and mostly important, the idea that it is wrong to think be wrong. The error is fundamental for the construction of knowledge, as well as unlearning. The knowledge is dynamic, changeable and, therefore, the rise of the apparent confusion, many questions, negotiation of concepts and the learn flexibility is the primordial bases for learning to learn, but also to learn to be a teacher, or teaching.

Neotropical Entomology, Jan 1, 2009

Cell hypertrophy was the first reaction of the gut epithelial cells of Aedes aegypti (L.), Anophe... more Cell hypertrophy was the first reaction of the gut epithelial cells of Aedes aegypti (L.), Anopheles albitarsis (Lynch-Arribálzaga) and Culex quinquefasciatus (Say) to the toxins of strains 2362 and S1116 of Bacillus sphaericus, as cells had an increase of intracellular secretory activity. Soon after the cell hypertrophy developed, vesicles were formed at the cell apical portion, which detached with the plasma membrane, characterizing a type of apocrine secretion like. The first pathway of contamination of the mosquito larvae by these bacteria is through the gut, by feeding. Depending on the species of Culicidae and on the bacterial strain used, the hypertrophy of the gut epithelium occurred between 5 and 15 min after exposure to the contaminated environment. The second aspect observed after hypertrophy was the increase in apocrine secretion. The basophilic vesicles that detached from the cells remained between the peritrophic membrane and the gut lumen, such vesicles were filled with material of unknown nature. The gut posterior region showed secretory activity in both control and treated larvae, being much more intense in bacteria-exposed larvae. There were remarkable differences in the epithelial cell reaction according to the toxins of the two bacterial strains, but C.quinquefasciatus was the most susceptible. Differences in the gut cell reactions to the toxins produced by the two bacterial strains are discussed.

Microsc Microanal, Jan 1, 2003

Neotropical Entomology 34(1): 047-057 (2005) Dufour Gland Occurence, Morphology and Ultrastructur... more Neotropical Entomology 34(1): 047-057 (2005) Dufour Gland Occurence, Morphology and Ultrastructure in Scaptogrigona postica Latreille (Hymenoptera: Apidae)

Annals of the Entomological …, Jan 1, 2011

Previously, we found that the fat body of Aspisoma lineatum Gyll (Coleoptera: Lampyridae) Þreßy l... more Previously, we found that the fat body of Aspisoma lineatum Gyll (Coleoptera: Lampyridae) Þreßy larvae is weakly bioluminescent. This tissue is very different from that of other insect larvae. It is macroscopically distinguished by its color (pinkish and whitish), morphology, and the absence of oenocytes. It is composed of trophocytes that are arranged in groups of globular units covered by a layer of basal lamina. The cytochemistry indicated that the trophocytes have glycoproteins, which are produced by a well-developed rough endoplasm reticulum (RER). Expanded RER cisterns indicated intense protein synthesis by the trophocytes. Lipid droplets are also present in the trophocytes. Charge-coupled device imaging showed that the fat body produces a continuous bioluminescence whose intensity is 2Ð3 orders of magnitude lower than that of the lanterns, a result that is explained by the lower contents of luciferin and luciferase in the fat body compared with the lanterns. Expression of different luciferase isozymes in the fat body and lanterns is conÞrmed by bioluminescence spectral and kinetic analyses. Trophocytes were identiÞed as the emitting cells, suggesting that the larval and adult lanternÕs photocytes may have evolved from fat body trophocytes.

… of Biodiversity and …, Jan 1, 2011

In the south of Brazil some species of bumblebees are disappearing, such as: Bombus bellicosus in... more In the south of Brazil some species of bumblebees are disappearing, such as: Bombus bellicosus in Paraná State. Insecticides and other pesticides and global warming are possible candidates for such phenomena, but none of them has been deeply studied. In forest fragments at southeast of Brazil (Sorocaba City, São Paulo State) tachinid fly larvae were found inside the abdomen of foraging females of Bombus morio and Bombus atratus. It is the first time that the occurrence of such parasitism is described for these species and it could be of some relationship to the disappearance of the genus Bombus.

Neotropical …, Jan 1, 2004

The mandibular glands of newly-emerged, nurse and forager workers, virgin and physogastric queens... more The mandibular glands of newly-emerged, nurse and forager workers, virgin and physogastric queens, and mature males of Scaptotrigona postica Latreille were studied under histological and morphometrical analyses. These glands present differences in their histology, according to the age and/or function of the individuals. The morphometric results showed that the mandibular glands have a very markedly secretory cicle, in which the secretion starts to be produced in newly emerged workers, being accumulated into the cytoplasm and reservoir in the nurses. In forager workers the cytoplasm presents many vacuoles, which are remaining of the secretion releasing. Physogastric queens showed the largest cellular and nuclear areas. On the contrary, the males presented the smallest ones.

Braz. J. Morphol. Sci, Jan 1, 2006

Differences in the ultrastructure and function of the mandibular glands in developing workers and... more Differences in the ultrastructure and function of the mandibular glands in developing workers and mature males of the meliponine stingless bee Scaptotrigona postica suggest that there are age-dependent variations in the contents of the secretion and glandular functions. In this work, we used transmission (TEM) and scanning (SEM) electron microscopy to examine the mandibular glands of S. postica workers of different ages and compared them with those of mature males. The gland anatomy did not vary between workers and males. However, the ultrastructure of the gland cells changed according to the worker's age, task, and sex. The mandibular gland cells in workers and males had a well developed smooth endoplasmic reticulum and pleomorphic mitochondria, indicating that the cells were involved in lipid synthesis. However, the secretion varied in morphology and electrondensity between workers and males, which suggested differences in its contents and, possibly, in glandular functions.

Revista Brasileira de Entomologia, Jan 1, 2006

Morphological, chemical and developmental aspects of the Dufour gland in some eusocial bees (Hyme... more Morphological, chemical and developmental aspects of the Dufour gland in some eusocial bees (Hymenoptera, Apidae): a review. The present revision focused on the more recent data about the Dufour gland in some eusocial bees, taking in account general aspects of its morphology, secretion chemical nature, bio-synthetic pathway and development. Many functions have been attributed to this gland in eusocial bees, but none are convincing. With the new data about this gland, not only the secretion chemical pathway of the Dufour gland may be reasonable understood, as its function in some eusocial bees, especially Apis mellifera Linné, 1758, which has been extensively studied in the last years.

Apidologie, Jan 1, 2006

Class III tegumentar glands were studied in workers, as well as in queens and males when availabl... more Class III tegumentar glands were studied in workers, as well as in queens and males when available, of 56 Meliponini species. The presence and development of these glands varies widely among and within species. However, the queen typically has more glands than do workers, and males rarely have any. Gland development in workers was evaluated by counting and determining the size of cells in histological sections. Laying queens were found to have more active gland cells than did virgins. Cell numbers and cell ultrastructure differed among glands similarly located in workers, queens and males. Cell size and ultrastructure also varied from tergite to tergite. In conclusion, since it is likely that most of them produce pheromones, the wide variability in these glands suggests that they are important to social interaction. stingless bee / tergal gland / histology / ultrastructure / worker / queen / male

Braz. J. Morphol. Sci, Jan 1, 2004

Histological aspects of late gametogenesis in Leptodactylus labyrinthicus and of unfertilized ooc... more Histological aspects of late gametogenesis in Leptodactylus labyrinthicus and of unfertilized oocytes collected from clutches in the field were studied by light microscopy. Specimens were collected during the reproductive period to determine why only 10% of the oocytes deposited in foam nests are fertilized. Sections of ovaries and oocytes were stained with hematoxylin and eosin, mercury bromophenol blue and toluidine blue. During the reproductive phase, the ovaries were completely developed and consisted of a sack-shaped, multilobular structure, with each lobe containing many oocytes in advanced developmental stages. Atretic oocytes were also seen in the ovaries during the reproductive phase. Oocyte development in the ovaries was considered synchronous, although few oocytes were seen in the early developmental stages. There were no differences in the morphology or staining of oocytes in the ovary and of unfertilized oocytes. Testicular development was synchronic with that of the ovary, with the testes also being fully developed during the reproductive period. Each seminiferous tubule had many cysts containing all of the phases of spermatogenesis, especially spermatids with different levels of nuclear condensation. Free spermatozoa were also observed in the lumen of the seminiferous tubule. The significant proportion of unfertilized oocytes present in many clutches may indicate that males produced an insufficient number of spermatozoa to fertilize all of the oocytes or that females deposited additional oocytes subsequent to spawning. These unfertilized oocytes are ingested by the larvae and may represent a reproductive strategy for increasing tadpole survival.

Brazilian Journal of Morphological …, Jan 1, 2005

In this study, we examined various aspects of ovarian development in adult honey bees queens (Api... more In this study, we examined various aspects of ovarian development in adult honey bees queens (Apis mellifera). Caged honey bee queens showed an initial programmed germ cell differentiation that was independent of any external or environmental stimulus. In young queens, division of the stem germ cells resulted in cysts of clone cells (cystocytes) that were connected through intercellular bridges and appeared as rosettes. The cystocytes started differentiate shortly before the queens reached sexual maturity (about 5 days old). The oocyte subsequently appeared as a large, stained cell connected to parallel, double rows of smaller cells, or nurse cells. If the queens did not mate, germ cell differentiation was "switched off", and development of the ovary was interrupted in an intermediate developmental stage, without follicular cell organization. Therefore, in such queens, there were no previtellogenic follicles. This finding could explain why virgin queens rarely lay eggs and why after fecundation they require several days to start laying. The absence of previtellogenic follicles may also indicate that some stimulus is required for continuation of the vitellogenesis and ovary development.

Insect …, Jan 1, 2005

Abstract In this paper we focus on the occurrence and morphological aspects of exocrine glands in... more Abstract In this paper we focus on the occurrence and morphological aspects of exocrine glands in several bee species. Morphology of head labial, mandibular, Dufour, and abdominal tegumentar glands was investigated under light microscopy, scanning electron microscopy and transmission electron microscopy. Most of such glands present cells with cytoplasm homogeneous and acidophilic, or contain small apparently empty vacuoles. The cytoplasm cells' ultrastructure showed a well developed smooth endoplasmic reticulum, many polymorphic mitochondria, rare Golgi, lipid droplets, myelin figures, and many basal and apical plasma membrane infoldings. All these results are discussed in the text.

Revista Brasileira de Zoologia, Jan 1, 2001

Journal of the Brazilian …, Jan 1, 2004

A secreção das glândulas mandibulares de operárias recém-emergidas, aprovisionadoras de cria e fo... more A secreção das glândulas mandibulares de operárias recém-emergidas, aprovisionadoras de cria e forrageiras, rainhas virgens e fisogástricas e machos de Melipona bicolor foi analisada através de cromatografia gasosa-espectrometria de massas. Foi verificado que a secreção é composta por uma mistura de hidrocarbonetos, álcoois, ésteres e ácidos. A secreção é casta-sexo específica e difere, também, de acordo com a tarefa desenvolvida pelas operárias e condição fisiológica reprodutiva das rainhas.