The lack of neuron staining techniques prior to the Nissl stain and the Golgi stain. Though Nissl’s technique came first, it only revealed neurons’ endoplasmic reticulum and parts of the cell body. It was only until Camillo Golgi developed his staining method, first known as the “black reaction”, that neurons as a whole were revealed. This was a groundbreaking technique that led to decade long debates about the nature of the nervous system, especially as to whether neurons were contiguous or separate. Since then, staining techniques have evolved to allow imaging of anything from axonal networks to individual neuropeptides. The Weigert-Weil stain enables us to visualise the myelin sheath of axons, giving us the opportunity to observe how connections are established throughout the brain. Modern techniques like in-situ hybridization (ISH) allow us to see which genes are expressed in a sample of neurons. The first step in ISH involves binding a labelled mRNA strand complementary to the mRNA produced by the gene of interest. The second step involves the introduction of a primary antibody with a variable region keyed to the mRNA label binds to the mRNA strand. The final step is injection of fluorescently labelled secondary antibodies with variable regions that recognize the species-specific heavy chain of the primary antibodies, and then imaging the cells with the appropriate wavelength of light. This technique allows scientists to know which neurons are expressing the gene of interest. Another modern staining method called immunohistochemistry (IHC) is also an antibody stain that uses fluorescently labelled antibodies to visualise certain molecules. However, as opposed to ISH, IHC reveals the presence of proteins such as neuropeptides, which can also be indicative of neuronal function.
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The history of neurology is a fragmented one fraught with disagreements, propositions, and rebuttals, often taking two steps forward and one step back. The earliest evidence of brain surgery dates back to prehistoric skulls with the marks of trepanation and subsequent recovery. Many millennia later in 400BCE, the Ancient Greeks discovered the separation between the central nervous system (CNS) and peripheral nervous system (PNS), though opinions were split as to the function of the brain. Two hundred years later, Galen of Ancient Rome found cerebrospinal fluid (CSF) in sheep skulls and, in the current of the bodily humours popular at the time, concluded that it was this liquid that gave rise to the conscious mind. Records of brain research in the Occident end there for nearly 1700 years, until the 16th century. During the Renaissance, Leonardo da Vinci restarts the study of brain anatomy and makes detailed drawings of the brain and its ventricles. In the mid-1500s, Andreas Vesalius dissects the bodies of executed prisoners and refutes Galen’s hypothesis that CSF is the seat of consciousness, claiming that the brain matter gives rise to the mind. However, in the 1600s, Descartes counters Vesalius’ theory in saying that the mind and brain are separate entities, thus giving birth to Dualism. This idea wouldn’t last long in the field of neurology as Willis and Wren’s study of brain anatomy led them to the same conclusion as Vesalius, brain matter not CSF holds human consciousness. Many small discoveries over the next centuries resulted in the discovery that nerves communicate via electricity and that different parts of the brain are responsible for different functions. The functional unit of the brain, the neuron, was only discovered in the 1900s when they were stained by Camillo Golgi. For decades Golgi and his colleague Santiago Ramon y Cajal would debate neuronal function. Golgi favoured the idea that neurons formed a contiguous system while Cajal hypothesized that neurons were separable, discrete units. Finally, as we approach the 21st century, the advent of the electron microscope vindicated Cajal’s theory. Neurons are in fact the basic unit of the brain and, though separate, they communicate via synapses.
Figure 1. A close-up image of an orchid. The flower shows two sterile whorls, the outer whorl has three sepals and the inner whorl has three petals. "Orchid" flickr photo by gssavage https://www.flickr.com/photos/gssavage/4696302471 under a Creative Commons (BY-ND) license.
The history of neurology is a fragmented one fraught with disagreements and centuries of stagnation. The earliest evidence of brain surgery dates back to prehistoric skulls with the marks of trepanation and subsequent recovery. Ancient Egyptians suggested that the heart was the seat of the soul rather than the brain. After that, the Ancient Greeks discovered the separation between the central nervous system (CNS) and peripheral nervous system (PNS), though opinions were split as to whether the brain matter actually served a purpose in consciousness. Later, in 200BCE, Galen of Ancient Rome discovered cerebrospinal fluid in sheep and concluded that it was this liquid that gave rise to the conscious mind. Records of brain research in the Orient end there for nearly 1700 years, until the Renaissance in the 16th century. Leonardo da Vinci picks up the study of brain anatomy and makes detailed drawings of the brain and its ventricles. Slightly later in the mid 1500s, Andreas Vesalius dissects the bodies of executed prisoners and refutes Galen’s hypothesis that CSF is the seat of consciousness, rather, the solid matter gives rise to the mind. However, in the 1600s, Descartes counters this hypothesis in saying that the mind and brain are separate entities, giving birth to philosophical dualism. But, around the same time, Thomas Willis and Christopher Wren dissect human bodies and come to the same conclusion as Vesalius, the wellspring of the mind is not CSF but brain matter. Many small discoveries over the next centuries resulted in our understanding that nerves communicate via electricity and that different parts of the brain are important for different functions. It was only in the early 1900s that neurons were stained (Camillo Golgi) and then hypothesized to be the individual units of the brain (Santiago Ramón y Cajal). Finally, as we approach the 21st century, research has brought to light the existence of different neuron types, and other classes of brain cells - such as glia - that serve a host of other purposes in maintaining brain function. Though we know much about the anatomy of the brain, we are still in the dark about its generation, possible regeneration, information processing capabilities, and how it gives rise to consciousness.
The uniformity of most modern crops is due to three genetic bottlenecks that took place during centuries of plant domestication. The first occurred at the start of sedentary, agricultural life, and could best be described as the domestication bottleneck. Early farmers only used a limited number of individuals as the progenitor species for their crop, resulting in a landrace. Thus, all of the subsequent crop plants came from the few those farmers had picked out, narrowing genetic variation in that plant. The second occurred during the first migratory phases of human civilization. When people migrated to new lands they would bring with them only a select number of plants from the landraces, which would once again reduce the genetic variation in the resulting crops. Finally, the third occurred many centuries later with the advent of modern genetic technology. Through the use of gene editing technology it became possible to create homogeneity for entire crop fields. Plants could now be edited to include genes of choice such as herbicide resistance, pest resistance, disease resistance, and many other traits, some of which allowed for the complete mechanization of farming. The final bottleneck has resulted in single plant genotypes propagated across entire fields, random variations becoming a thing of the past.
Sound perception and production in birds, especially oscines, has been the subject of much research. Birds’ singing and song learning systems have been studied from perspectives ranging from mechanical through neurological to social and adaptive. Mechanically speaking, birds produce song via the syrinx, an analog to the human larynx. Found at the entrance of the bronchioles, the syrinx is a group of connective tissues, cartilage rings, and membranes that vibrate in concert to produce sound. Sound itself comes not from the vibration of the medial tympaniform membranes but from connective tissue at the end of each bronchus that sticks into the syringeal lumen. From a neurological point of view, bird song perception, production, and learning originates in a series of neuronal nuclei heretofore referred to as the song pathway. Perception of song begins in auditory field L in conjunction with the NCM and CMM areas. These signals are then passed through the HVC, area X, LMAN, and DLM which all have song selective neurons that discriminate between different song types. Song production also comes from the song pathway and uses the same nuclei. Firstly, main auditory field L projects to both the HVC and RA, and the HVC itself projects to the RA. Secondly, from the RA is a projection to nXIIts, from which there is direct innervation of the syrinx, and thus, song production. Song learning also takes place in the song pathway, though this is less well understood and seems to have to do with the expression of immediate early genes (IEGs) such as ZENK in different neuronal nuclei depending on the acoustic environment.
A recent study by The New England Journal of Medicine has shown that public research institutes have had increased contribution to drug discovery. Since the dawn of biotechnology, it has generally been the case that public research institutions perform the basic research necessary to understand disease mechanisms while corporate research has been focused on developing drugs to treat diseases. However, after two acts passed in the mid 1980s, federally funded institutions and laboratories were granted the possibility to both freely publish their inventions in the scientific literature and convert them into intellectual property for commercialization. With a decade of delay, this change was reflected in the percentage of FDA approved drugs originating in the public sector. Between 1981 and 1999, only 7.6% of the FDA approved biological molecules came from non-industry sources. Whereas, between 1998 and 2007, 24.1% of the FDA approved biological molecules came from public research institutions. Lastly, the study suggests that public sector research aims to discover drugs that are expected to have a large clinical impact.
Building the Figure
I created a Google Slides presentation with a blank template. I changed the size of the slide by going to the File tab, scrolling down to Page Setup, choosing the Custom option, and making the slide 15.15 x 7.85 in. I added the “close-up”, “contextual”, and “sylvan_map” images to the slide. I cropped the “sylvan_map” image to include only the map up until right hand most edge of Parking Lot 44. By right clicking the “sylvan_map” image and going to Format options, and opening the Size & Rotation dropdown menu, I scaled the image to 9.84 x 7.95 in. Using the same method, I scaled both the “close-up” and “contextual” images to 5.31 x 3.92 in. I placed the “sylvan_map” image flush against the right side of the slide. I placed the “close-up” image above the “contextual” image, and fitted them in the remaining space, flush against the left side of the slide.
Self care: 575 min
I woke up and took a shower for 5 minutes. I made and drank a protein shake for 5 minutes. I made and drank my coffee over 10 minutes. I acquired a coffee from the cafeteria and drank it over about 15 minutes. I had dinner which took 10 minutes. I brushed my teeth for 5 minutes. I read my book for 75 minutes. I slept for 450 minutes.
Homework: 440 min
Class: 330 min
Travel: 50 min
The documents both start with the title of the paper followed by the names of the authors. Though both abstracts are found at the start of each paper, the slime mold paper labels the abstract as such while the leaf-mining paper does not. The leaf-mining paper is structured like classic primary literature, featuring level 1 headings for the introduction, methods, results, discussion, and references sections, as well as various level 2 headings within each section. However, the slime mold paper is organized by topic using only level 1 headers, as it is a review article rather than primary literature.
The abstracts of both papers are short paragraphs describing the object of and reason for the study. The introduction to the leaf-mining paper opens with an explanation as to why the subject of the study was chosen, followed by a series of explanatory paragraphs concerning the reasons for the study. The first section of the slime mold paper describes the conceptual question at hand and addresses the underlying reasons for the multiple studies and experiments referenced throughout the paper.