Drafts

As female foals grow, like the foals observed here, they continue to practice behaviors that their mothers preform. When they reach about 4 months old, they begin to break away and behave on their own gradually. One way that they do this, is by grazing more often, as opposed to nursing (Crowell-Davis, 2007). The foals’ large amount of time alone indicates there independence from their mothers and can be an important sign of growth for the young females (Crowell- Davis, 2007). The other behaviors that they do on their own, grooming and observation, are also significant to their growth because it also shows how independent and aware they are. It shows the higher mares that soon the foals will be able to fend for themselves.

The authors use both mice and rats in their experiment. Mice are used because their genome is largely similar to the human genome. Rats were used because their genome is 92% similar to mice. Rats were also used because they are larger than mice, which makes them a good model organism for examining retinal circuitry. The authors first cloned melanopsin cDNA in rat cells to show that the protein sequence is nearly identical to that of mice. Then they generated specific antibodies targeting melanopsin to show the subset of cells that contained the protein. Tau-lacZ targeting shows the projections of melanopsin positive cells to the SCN and other regions of the brain. Lastly, they used a combination of immunofluorescence and Lucifer Yellow to show that intrinsically photosensitive RGC’s were melanopsin positive.

The objective for this study is to understand the mechanism of non-visual reflexes such as regulation of the circadian clock and pupillary reflexes. The suprachiasmatic nucleus (SCN) is a site for photoentrainment in the brain. A portion of light-sensitive retinal ganglion cells protrude into the SCN. The authors hypothesized that melanopsin is a photopigment on the retinal ganglion cells (RPG’s) that generate action potentials to the brain in response to light, and play a role in photoentrainment. Although it was known that some RPG’s are photosensitive, the reasons for this phenomenon were unknown. It was also known that rods and cones are not photoentraining receptors. Provided this context, the reason for the study was to understand the function of RPG photosensitivity, and to use them to study the pathway that gives rise to photoentrainment.

There are five major functions of sleep as defined by neuroscientists. These are energy conservation, reinforcement of ecological niche, body restoration, brain restoration, and memory consolidation. There are four major brain regions that are responsible for sleep. The basal forebrain causes slow wave sleep via GABAergic projections to the hypothalamus. The brainstem, specifically the reticular formation, activates forebrain to wakefulness via acetylcholine and norepinephrine. The pons induces REM sleep via GABAergic and glycinergic projections to the spinal motor neurons to suppress motor activity. The hypothalamus coordinates the circadian rhythm and switches between states of sleep via hypocretin projections to the other three brain regions aforementioned.

Lucy's skeleton was found by Donald Johanson and Tom Gray in 1974 in Ethiopia. An ulna was spotted that was identifued as a hominid, a long period of excavation began which presented them with forty percent of a single hominid skeleton. This skeleton is a member of the family Hominidae which encompasses all species originating after humans and ape's split. A defining characteristic of all hominids is that they are able to walk upright and have bipedal locomotion. There legs lie directly underneath their pelvis. Lucy showed key characteristics that pointing to bipedality. Her skeleton is approximately 3.2 million years old.

Gene therapy is known as the ability for gene improvement by altering genes usually for the purpose of treating a disease. A normal gene is inserted into a genome which then replaces an abnormal gene. There are multiple gene therapy protocols that have been approved for clinical use although some have been successful there is still a lot left to understand. Two specific types of gene therapy are germline gene therapy and gene therapy of somatic cells, the key difference being that using somatic cells so future generations can’t inherit it, which is not the case for germline gene therapy. Some difficulties that arise with gene therapy is that a vector is needed in order to release the gene into the stem cell. This vector is a very specific one which cannot elicit a response from the immune system and has to be able to be produced in a large scale. The vector has to express the gene for the patient’s entire life.

Phloem is like plant’s version of blood-it transports nutrients up and down the plant. Extra phloem is sent to the roots for storage. Force is generated at the source-where the nutrients are going (also by where they are coming from). Phloem forces are positive pressure. The destination generates pressure lower than source-all positive pressures, no tension. Phloem cells are much smaller and have thinner cell walls than xylem. The outer part of phloem gives structure-bundle sheath. The primary phloem is the first phloem-first formed.  The secondary phloem is made after primary a d comes after vascular cambium. In between shoot meristem and root meristems are primary tissues, xylem and phloem differentiate after these points. In a tree, a new meristem differentiates in the trunk-this is the cambium which makes new cells (trees).

Gymnosperm phloem does not have sieve tubes, only single cells. Sieve plates are on the side of the cell-works like a network rather than a pipe. These are called sieve areas. It is not understood how this works because sieve areas are filled with endoplasmic reticulum which blocks flow. The presence of membranes would mean that there can’t be a bulk flow, but it doesn’t seem to be possible in gymnosperms.

The conclusion of the study was that soil temperatures at or above 23 degrees C inhibit root growth and respiration both long and short term in A. stolonifera,and the specific maintenance respiration rates of A. stoloniferawere significantly higher than A. scabraat higher temperatures. Increased soil temperatures actually caused A. scabrato thrive and it can survive higher temperatures. The original hypothesis was supported.

The purpose of this study was to determine how rising temperatures (due to climate change) are affecting root growth, plant survival, carbohydrate metabolism, and root respiration rate in environments where plants are very temperature sensitive, and to better understand how roots maintain growth and function under high soil temperature conditions. The hypothesis was that A. stoloniferawould have lower root respiration responses than A. scabraat higher temperatures.