The way a research paper is organized reflects the research design.  Scientific papers follow a strict format that is designed to be helpful to both writer and reader.  In writing a paper for publication in a scientific journal, such attributes as beauty, cleverness, and style are not required.  What is required is a clear, logical, orderly presentation of your specific question, how you planned to answer it, what your results were, and what you ultimately found.  Emphasis should be on good grammar and precise wording.

 A scientific paper should be composed of the following sections:  Title, Abstract, Introduction, Methods, Results, Discussion and Literature Cited.  Each section heading should be centered on their line and followed by the text for that section.

 Below you will find a brief description of each element described above.  Each heading is followed by a published example in order for you to gain a better picture of what is required and to serve as a guide for comparison to your finished work.

The title should tell the reader what klnd of work is being reported.  Optimally, it should detail the (1) organism studied, (2) the system examined, (3) and the variables that were manipulated.  Some grammatical latitude is allowed, but overall it should be simple, direct, and informative.  Here are some proper examples:

THE EFFECT OF TEMPERATURE
ON RATE OF HEARTBEAT IN DAPHNIA

VERTEBRATE EPITHELIAL TRANSPORT:
A COMPARISON OF TWO SUB-SPECIES OF RANA PIPIENS

CONTRACTION OF SMOOTH MUSCLE CELLS
FROM BUFO MARINUS STOMACH

 The Abstract is a one or two paragraph summary of the entire article. This section gives the major arguments and results of the work.  It is designed to help the reader decide whether the material in the paper is worth while reading.  Compacting months and often years of mental toil and data collection/analysis into a few sentences is not easy and requires practice.

Purpose.  Endothelin-1 (ET-1), a potent vasoconstrictive peptide, with a wide spectrum of other physiological effects, has recently been shown to be expressed in a variety of tissues outside the cardiovascular system including the anterior segment of the eye.  We have used a well characterized bovine corneal endothelial cell (BCEC) culture model to investigate the possibility that ET-1 may be an autocrine effector of BCEC function.  More specifically, we determined whether these cells synthesize, store, and secrete ET-1, express ET receptors and, through their activation, induce inositol phosphate metabolism and mobilization of intracellular calcium (Ca2+i).
Methods.  Indirect immunofluorescence using monoclonal and polyclonal antibodies to ET-1 was used to detect the presence of ET-1 in BCEC and radioimmunoassay was employed to test for secretion of ET-1 into culture medium.  Radioligand binding studies were conducted to identify and characterize ET receptors.  To assay for second messenger responses to ET-1, phospholipase C activity was measured as the accumulation of inositol phosphates in BCEC prelabeled with 3H-myoinositol, and intracellular calcium ([Ca2+]I ) was monitored in single cells loaded with the Ca2+-sensitive probe fura-2.  3H-thymidine incorporation was used as a measure of DNA synthesis.
Results.  Indirect immunofluorescence  revealed a punctate cytoplasmic localization of ET-1 in BCEC.  ET-1 was present in culture medium and increased with time in culture.  Secretion of ET-1 by BCEC was stimulated by cAMP or by agonists that elevate intracellular cAMP, and appeared to be inhibited by increases in intracellular Ca2+.  Equilibrium binding experiments with [125I] ET-1 indicated the presence of a single population of saturable binding sites with a KD of 0.22 nM.  Maximal binding was 475 fmol/mg protein.  In competition experiments, ET-1 and ET-3 displaced [125I]ET-1 with a Ki of 1.1 nM and 337 nM, respectively.  The 300-fold binding affinity of ET-1 over ET-3 was consistent with an ET-1 selective, ETA receptor.  In the presence of 10 mM Li+, ET-1 promoted a dose dependent accumulation of inositol phosphates in BCEC with an EC50 of 2.3 nM, an ECmin of 0.8 nM, and an ECmax of 10 nM.  When exposed to ET-1, BCEC exhibited a rapid increase in [Ca2+]i  that usually subsided to near baseline levels within 2 min.  ET-1 also stimulated DNA synthesis, either alone or synergistically with EGF.
Conclusions.   Synthesis and secretion of ET-1 by BCEC, the presence of  ET-1 receptors coupled to characteristic second messenger responses, and the stimulation of DNA synthesis by ET-1 strongly  suggest that ET-1 may be an autocrine regulator of BCEC function.

     The lntroduction should present the question being investigated in the context of what is already known about the subject.  Background information on the topic/system being studied is needed since it suggests why the topic is of interest and of importance. Related findings by other investigators are mentioned here. The Introduction must also "set the stage" for the hypothesis(es) stated at the end of this section.  The hypothesis(es) should follow logically from what precedes it, and should not "come out of left field".  A proper example is:

THE ROLE OF STORED GLYCOGEN DURING LONG-TERM TEMPERATURE ACCLIMATION IN THE FRESHWATER CRAYFISH, ORCOMECTES VIRILES

Arthur M. Jungreis
Comparative Biochemistry and Physiology. 1968. 24: 1-6.

Introduction

 In Crustacea, glycogen metabolism has been associated with chitin synthesis (Renaus, 1949; Passano, 1960).  However, the role played by glycogen in intermediary metabolism under normal conditions or during starvation is not clear.  According to Renaud, crustacean intermediary metabolism centers around glycogen and fatty acids, while according to Scheer and co-workers (Scheer & Scheer, 1951; Rincaid & Scheer, 1952) the primary energy source is protein and not carbohydrate and fat.  When 14C-labeled glucose was inducted into the spiny lobster Panulirus, it appeared almost exclusively as labeled glycogen rather that labeled C02 (Scheer & Scheer, 1951). Furthermore, during an artificial period of starvation, the total glycogen content in Panulirus did not decrease (Sheer & Shceer, 1951).
 To determine the role of glycogen as a metabolic source of energy during acclimation in long-term starved crayfish Orconectes virilis, glycogen content was analyzed in a variety of tissues after 45 days of acclimation.

 This sectlon should provide the necessary details of experimental procedure and design so that others could reproduce the experiment.  Specific, published techniques can be cited without going into detail.  This section should be written in the past tense, thus telling what was done not what one should do.  Diagrams of the instrumentation used or study areas are sometimes helpful.

GRADED CONTRACTIONS IN MUSCLE STRIPS AND SINGLE CELLS
FROM BUFO MARINUS STOMACH

Roland M. Bagby and Bruce A. Fisher
American Journal of Physiology. 1973. 225: 105-109.

Methods and Materials

 Adult specimen of Bufo marinus (200-300g) were double pithed and the stomachs were removed.  Single smooth muscle cells were prepared according to Bagby et al. (1971).
 For preparing strips, stomachs were stretched over tempered-glass rods, the serosa was peeled away, and strips of muscle 2mm wide were separated from the underlying mucosa.  Microscope observations of sections cut from strips prepared in this manner showed that the strips contained only the circular smooth muscle layer.  The strips were mounted vertically in a 100-ml bath filled with a modified Harris-Ringer solution (Harris) of the following composition, in grams per liter: NaCl, 5.2: KCl, 0.22; NaHCO3, 2,52: Na2HP04-12H20, 0.83; CaCl2, 0.28; MgS04, 0.12; and glucose, 0.54. The upper end of a strip was attached to the moving element of a LVDT-type of isotonic transducer (Narco Bio-Systems, Inc.), which had been modified to weigh only 225 mg. The weight of the element and attached muscle could be counter-balance to produce the desired load on the muscle. In this investigation, a load of 100mg was used for muscle strips 1.5-2.0 mm in diameter.  DC Pulses from a Grass S44 stimulator and SIU5 stimulus-isolation unit were applied transmurally by platinum wire-loop electrodes surrounding the strips.  Responses were recorded on a Physiograph DMP-4 polygraph.
Single smooth muscle cells were pipetted onto slides having two silvered strips 6 mm apart which were connected to a Grass S44 stimulator and SIU5 stimulus-isolation unit, allowing a d-c field stimulus to be passed through the droplet containing the cells. Responses were recorded on 16 mm Tri-X reversal film with a Bolex movie camera and Wild phototube mounted on a Nikon Suke microscope with phase-contrast optics.  The time of stimulus was marked when stimulus was applied.  A negative for making prints was obtained by making a contact print of the original on Eastman fine-grain release positive film.

     The results of the experiment should be presented without comment, interpretation or bias.  Graphs, tables and figures can be very useful in this section to assist in explanations.  However, they may not substitute for a verbal summary.
 Statistical tests that were applied to your raw data are reported in this section. Again, interpretations and conclusions about your findings are saved for the discussion section.

PREY PREFERENCE AND HUNTING HABITAT SELECTION IN BARN OWL

Stephen J. Fast and Harrison W. Ambrose, III
The American Midland Naturalist. 1976. 96: 503-507

Results

 In Situation 1, both kinds of rodents were present in both habitats. The owl took significantly more rodents from the field habitat (21) than from the woods (7).  The comparison between his prey choices (10 Microtus, nine Peromyscus) borders on significance.
 A field-woods hunting habitat choice with Peromyscus was offered in Situation 2. The owl took significantly more mice (11) from the field than from the woods (3).
Situation 3 presented the field-woods choice using only Microtus.  Again, significantly more rodents were taken from the field (12) than from the woods.
 In Situation 4, which allowed the owl a choice between the two species in the woods only, the number of Microtus eaten (12), was twice the number of Peromyscus (6). These results, although suggestive, are not statistically significant, probably due to the small sample size.
 The owl was permitted to choose between the two prey species again in Situation 5, this time in the field only.  Significantly more Microtus (10) were eaten than Peromyscus (2).
 In Situations 1, 4, and 5, where the owl had the opportunity to choose between the two species of prey, a total of 41 Microtus and 17 Peromyscus were taken. Situations 1,2, and 3 gave the owl the field-woods choice: a total of 44 rodents were taken from the field and 13 from the woods.  These results, when subjected the  2 test, show Microtus to be significantly the "preferred" prey item, and the field to be the preferred hunting habitat.

 This section evaluates the meaning of your results in light of the original question or hypothesis and in addition, points out their biological significance.  If the results are unexpected, you should attempt to explain why and possibly point out directions for future research that may more clearly define the situation.  The discussion should build upon the introduction by describing the significance of the experiment in terms of previous work without trying to review the entire field.

INSENSITIVITY OF LEPIDOPTERAN TISSUES TO OUABAIN: PHYSIOLOGICAL MECHANISMS FOR PROTECTION FROM CARDIAC GLYCOSIDES

Gerald L. Vaughan and Arthur M. Jungreis
Journal of Insect Physiology. 1977. 23: 585-589.

Discussion

 The Na+/K+-ATPase is generally responsible for alkali cation transport in animal cells (Skou, 1957) and is inhibited by ouabain and similar cardiac glycosides (Glynn, 1957).  The Lepidoptera used in this study and perhaps similar phytophagous insects are unusual in several respects, among which is the absence of measurable Na+/K+-ATPase in tissues other than those rich in neuronal material (Vaughan and Jungreis, 1976; Jungreis and Vaughan, 1976, 1977).  In addition to having epithelia which appear to lack Na+/K+-ATPase and concomitant cardiac glycoside sensitivity, these insects differ from other animals in at least one other important respect -- high levels of K+ and low levels of Na+ in blood ) Florkin and Jeuniaux, 1974).  The location of Na+/K+-ATPase  in neuronal tissue, however, and the K+ and Na+ content of tissues from the head of D. plexippus are evidence that these insects maintain the same mechanisms for sustaining action potentials in the central nervous system as do the animals whose blood is high in Na+ and low in K+ (Treherne, 1967, 1976).
 The physiological character of the insects in this study and the information reported here suggest a convincing mechanism for the insensitivity of phytophagous Lepidoptera to cardiac glycosides.  Considering the refractory nature of D. plexippus to cardiac glycosides, it is not unexpected (Jungreis and Vaughan, 1977) that Na+/K+-ATPase from this organism would have a low affinity for ouabain and thus the low sensitivity noted in Fig. 4.  More interesting is the lack of observable in vitro perturbation in M. sexta, which possesses Na+/K+-ATPase highly sensitive to ouabain in vitro (Fig. 4). We suggest that following introduction of cardiac glycoside, but prior to storage, degradation and excretion (Duffey and Scudder, 1972), high haemolymph K+ lessens or totally blocks (Fig. 5) the effect of the glycoside on nervous tissue, possibly the only tissue containing Na+/K+-ATPase.  During this period of K+ protection, glycosides are either rapidly excreted or stored in various tissues.  Based on this model and the suggestion that the neuronal sheathe (Treherne, 1976) affords additional protection, these insects would not need other special enzymatic adaptations to cope with the problems of cardial glycoside ingestion.
 The slight but significant sensitivity to the Na+/K+-ATPase in D. plexippus requires additional interpretation.  lt offers an obvious explanation for the observation (Urquart, 1961) that Monarches with the highest levels of cardiac glycosides are smaller and less successful.  The total amounts of glycoside they contain (Brower and Glazier, 1975) are comparable to those used in this study.  The so-called physiological burden (Brower and Glazier, 1975) of cardiac glycoside ingestion in the Monarch butterfly had been considered to be a function of the cost of metabolizing and storing the cardiac glycoside with little regard for the possibility that the insect itself may possess cardiac glycoside-sensitive moieties.  A reassessment of the true situation must accommodate the toxic effects of very high levels of cardiac glycoside on neuronal Na+/K+-ATPase as well as the metabolic cost of sequestration.

 All published work cited in your paper must be alphabetically listed in this sectlon.   (Those who know bibliographic programs designed for this use are encouraged to do so.)  Each entry should contain the author(s), the title of the article, the journal from which the article was found, the volume number and the inclusive pages.  List the citations in alphabetical order of the last name of the first author.  Use single space within a citation and double space between citations. The second line is indented. Books or sections from books are listed in a slightly different format.  Here are some examples to help you out.

Ambrose, H.W., III. 1972. Effect of habitat familiarity and toe clipping on rate of owl   predation in Microtus pennsylvanicus. Journal of Mammology. 53: 909-912.
Link, G.R.R. 1928.  Bacteria in relation to plant diseases. E.O. Jordan and I.S. Falk, eds.  The newer knowledge of bacteriology and immunology. University of Chicago   Press, Chicago, Ill. p.590-606.

 Graphic representations of data or study location is often quite helpful in making the information transfer from writer to reader efficient and complete.  The emphasis should be on simplicity, succinctness and clarity.  In all cases, axis should be properly labeled. Table and figure captions should always be present and completely describe all variables and trends; including: what organism/preparation was used, how many as well as statistical parameters. Look at published articles as examples.

Author: Kenneth M. Crawford 

Last Update : Thursday, August 13, 1999 - 9:31:07 AM