Skip to content

Devlin Crose's Blog

Just another weblog

Tag Archives: Devlin

In the city of Oaks – Stellenbosch! First year at Simonsberg residence. I am not much of a fan of Rugby, more of an ocean person – Rugby plays a big part in the social scene of Stellenbosch. The big team is called the Maties, as in the Maties Rugby Club. There is also a lot of Tennis, track and field and soccer – which I enjoyed much more! My favorite course were Ancient Cultures, sports sciences and psychology. One favorite professor I remember is Sulina Green. Loved to get a quick bite over at KFC on Corner Drostdy Complex & Bird Street. Occasional movie at Cinemuse on Ryneveld Street. Many fun times at The Brazen Head pub! Great food, and sports. Favorite surf locations – Long beach Kommetjie, Cape Town False Bay surfers corner, very nice beach – watch for sharks! Bay of Plenty in Durban – great night life. Be sure to check out Florida road for the happs! My favorite is Joe Cool’s, near the belmont and tropicana. Marine world is a fun place when the waves aren’t working. My shop, 26 Degrees South refers to the latitude of Cresta, SA. We share the parallel with Western Australia, Dirk Hartog Island where there are some nice Westerly breaks – so I’m told! The Gold Coast Australia, Chañaral , Chile, Pontal do Paraná Brazil and the famous Grajagan Surf Resort! The reason I own this shop is due to my life long love of surfing. I get to travel the world with my tri-fin to bring back products for my boutique shop!


Tags: , ,

Information transfer

Nearly every multicellular organism passes through a life cycle stage where it exists as a single undifferentiated cell or as a small number of undifferentiated cells. This developmental stage contains molecular information which specifies the entire course of development encoded in its many thousands of genes. At the molecular level, genes are used to make proteins, many of which act as enzymes, biological catalysts which drive the thousands of different biochemical reactions inside cells. 

Development (Zarucha, T. 2004)

Epigenesis The view of development where structures arise progressively (p. 95).

Kaspar Friedrich Wolff (1733–1794) observed that during chick development, embryonic structures, such as the heart and kidneys, look very different from the adult structures into which they develop. If preformation were the mechanism by which development was proceeding, embryonic and adult structures would appear identical, only differing in their size. Wolff also observed that structures such as the heart actually developed anew in each embryo. The view of development that Wolff observed, where structures arise progressively, is known as epigenesis (a Greek word meaning “upon formation”). Interestingly, the idea of epigenesis as the over-riding mechanism of development was first recognized and supported by the Greek philosopher Aristotle (384–322 B.C.).


Epigenetic Inheritance (Smelser, N. J. & Baltes, P. B., 2001, pp – 4800 – 4804) ‘Epigenetic inheritance’ is a term used to describe the transmission from one generation to the next of structural and functional variations that do not depend on genetic differences. In its broadest sense, the term includes the transmission of nongenetic variations in behavior, but its use is usually restricted to the inheritance in cell lineages of variations that are not based on changes in the genetic information carried in DNA. Such heritable epigenetic changes are part of normal development but there is increasing evidence that they can also be transmitted from one generation of organisms to the next. Epigenetic inheritance therefore has practical implications for medicine and agriculture, and theoretical implications for ideas about heredity and evolution. The introduction of the term ‘epigenetics’ by the British embryologist Conrad Waddington in 1947 (see Waddington 1975), reflected a growing interest in the relationship between genes and development, an interest which increased as the molecular nature of the gene was unraveled. Waddington coined the term epigenetics for the study of the causal mechanisms of development; the adjective ‘epigenetic’ is applied to the processes through which the genetic information in a fertilized egg is expressed and used in the production of the adult form, the visible phenotype. The concept of epigenetic inheritance was therefore extended and now has both a narrow and a broad meaning. The narrow meaning limits it to cell memory in lineages within an organism, whereas the broad meaning includes the transmission of epigenetic information between any reproducing entities—cells, individuals, and even groups of individuals. This article focuses first on epigenetic inheritance in cell lines, and then discusses the consequences of the transmission of epigenetic variations between generations of individuals.

Mechanisms of Transmission

The systems that underlie epigenetic inheritance and enable the phenotypic expression of the genetic information in a cell to be transmitted to the next generation have been called epigenetic inheritance systems (EISs). Three broad types have been characterized (Jablonka and Lamb 1995): steady-state systems, structural systems, and chromatin-marking systems.

Tags: , , , ,

Aristotle (384–322 B.C.) described the two historically important models of development known as preformation and epigenesis. According to preformationist theories, an embryo or miniature individual preexists in either the mother’s egg or the father’s semen and begins to grow when properly stimulated. Some preformationists believed that all the embryos that would ever develop had been formed by God at the Creation. Aristotle actually favored the theory of epigenesis, which assumes that the embryo begins as an undifferentiated mass and that new parts are added during development. Aristotle thought that the female parent contributed only unorganized matter to the embryo. He argued that semen from the male parent provided the “form,” or soul, that guided development and that the first part of the new organism to be formed was the heart. Aristotle’s theory of epigenetic development dominated the science of embryology until the work of physiologist William Harvey (1578–1657) raised doubts about many aspects of classical theories. In his studies of embryology, as in his research on the circulation of the blood, Harvey was inspired by the work of his teacher, Girolamo Fabrici (ca.1533–1619). Some historians think that Fabrici should be considered the founder of modern embryology because of the importance of his embryological texts: On the Formed Fetus and On the Development of the Egg and the Chick. Harvey’s On the Generation of Animals was not published until 1651, but it was the result of many years of research. Although Harvey began these investigations in order to provide experimental proof for Aristotle’s theory of epigenesis, his observations proved that many aspects of Aristotle’s theory of generation were wrong.
Using deer that had mated, Harvey dissected the uterus and searched for the embryo. He was unable to find any signs of a developing embryo in the uterus until about six or seven weeks after mating had taken place. In addition to his experiments on deer, Harvey carried out systematic studies of the developing chick egg. His observations convinced him that generation proceeded by epigenesis, that is, the gradual addition of parts. Nevertheless, many of Harvey’s followers rejected epigenesis and turned to theories of preformation.
K. Lee Lerner and Brenda Wilmoth Lerner ed., 2004. The GALE ENCYCLOPEDIA of Science, 3rd ed. v. 2. Thomson/Gale. Publisher’s

Tags: , , ,