Procedures utilizing Chelex 100 chelating resin have been developed for extracting DNA from forensic-type samples for use with the PCR. The procedures are simple, rapid, involve no organic solvents and do not require multiple tube transfers for most types of samples. The extraction of DNA from semen and very small bloodstains using Chelex 100 is as efficient or more efficient than using proteinase K and phenol-chloroform extraction. DNA extracted from bloodstains seems less prone to contain PCR inhibitors when prepared by this method. The Chelex method has been used with amplification and typing at the HLA DQ alpha locus to obtain the DQ alpha genotypes of many different types of samples, including whole blood, bloodstains, seminal stains, buccal swabs, hair and post-coital samples. The results of a concordance study are presented in which the DQ alpha genotypes of 84 samples prepared using Chelex or using conventional phenol-chloroform extraction are compared. The genotypes obtained using the two different extraction methods were identical for all samples tested.

Chelex 100 as a Medium for Simple Extraction of DNA for PCR-Based Typing from Forensic Material

Angiogenesis is thought to depend on a precise balance of positive and negative regulation. Angiopoietin-1 (Ang1) is an angiogenic factor that signals through the endothelial cell-specific Tie2 receptor tyrosine kinase. Like vascular endothelial growth factor, Ang1 is essential for normal vascular development in the mouse. An Ang1 relative, termed angiopoietin-2 (Ang2), was identified by homology screening and shown to be a naturally occurring antagonist for Ang1 and Tie2. Transgenic overexpression of Ang2 disrupts blood vessel formation in the mouse embryo. In adult mice and humans, Ang2 is expressed only at sites of vascular remodeling. Natural antagonists for vertebrate receptor tyrosine kinases are atypical; thus, the discovery of a negative regulator acting on Tie2 emphasizes the need for exquisite regulation of this angiogenic receptor system.

https://science.sciencemag.org/content/sci/277/5322/55.full.pdf

Angiopoietin-2, a Natural Antagonist for Tie2 That Disrupts in vivo Angiogenesis

CONTENTS INTRODUCTION . . . . . . . . ... . . ... . . . . . . . . . . . . . . . ... . . . . . . . . . . . ...... . ... ... . . . . . . . . . . . . . . . ... ....... ... . . . . . . . . . . . ... . . ... . . . . . 664 CELL DEATH IN CAENORHABDITIS ELEGANS .... .. ..... . . . . 664 Programmed Cell Death . ... . . . . . . . . ... . . . . . ... . . . . . . . . . . . . . . . .. . . . . . . 665 Pathological Cell Deaths ....... . ........ ... . . . . . . . . . . . . . . .. . . . . . . . .. . . . . . . . . . . . . . . . . . . ........ 669 Summary . ... . . . . . . . . . .. .. '" . . .. . . . ... .... . . . . . .... . . ..... . . . ....... . . . . . . . . . . .. . . . . . . . . . . . . ...... 670 CELL DEATH IN OTHER ANIMALS .. . .. . . . . . . . . . . . . . . . . . . . . . . .. .. .. . ... . . . ... . . . ... . . ... . . . . . . . .. ... . . . . ... . . . ... ...... 670 Cell Death During the Metamorphosis of Moths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . 671 Deaths of Vertebrate Neurons Deprived of Growth Factors . . . ...... .... . . . . . ...... ... . 673 Cell Death ol'lhymocytes . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . ... . . . . . . . . . . . . ..... . ... . . . . . . . . . . . . . . . . . . .. . ... . . . . . ... 675 Cell Death in the Regressing Rat Prostate ........ . 678 FUNCTIONS OF CELL DEATH 679 Cells That Appear to Have No Function .. ..... . . .... . . . . .... . ...... 680 Cells That Are Generated in Excess ......... ......... . . . . . . . . . . . 683 Cells That Develop Improperly . .. . . . .. . . . . . . . . . . . . . . . . . . . . ....... . . . . . . . . . . . . . . . . .. .. . . ....... ... .. . ... . . ...... 684 Cells That Have Completed Their Functions . . . . . . . . . .... . . ... . . . . . . . . . . . ... . . . . . . ... ... .. . . .. ... .. . . ... . 684 Cells That Are Harmful 685 MECHANISMS OF CELL DEATH 685 Cell Death Is an Active Process . . . .. . . ... . . . . . . . . ... . ...... . . .. 685 Control of the Cell Death Process ....... . 686 Mechanisms That Kill Cells . . . ... . . ... . ... . . . . . . . . . ... . . ... . ... . . . . . . .. . . . .. .. .... . . . . . . . .. 687 Engulfment of Dead Cells . . . ....... . . . . . . . 689 Degradation of Dead Cells. . . . . . . ... ... . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 690 Future Prospects 690

Mechanisms and Functions of Cell Death

The neurotrophins are a small group of dimeric proteins that profoundly affect the development of the nervous system of vertebrates. Recent studies have established clear correlations between the survival requirements for different neurotrophins of functionally distinct subsets of sensory neurons. The biological role of the neurotrophins is not limited to the prevention of programmed cell death of specific groups of neurons during development. Neurotrophin-3 in particular seems to act on neurons well before the period of target innervation and of normally occuning cell death. In animals lacking functional neurotrophin or receptor genes, neuronal numbers do not seem to be massively reduced in the CNS, unlike in the PNS. Finally, rapid actions of neurotrophins on synaptic efficacy, as well as the regulation of their mRNAs by electrical activity, suggest that neurotrophins might play important roles in regulating neuronal connectivity in the developing and in the adult central nervous system.

Physiology of the neurotrophins

ERKs: A family of protein-serine/threonine kinases that are activated and tyrosine phosphorylated in response to insulin and NGF

The development and maintenance of the nervous system depends on proteins known as neurotrophic factors. Although the prototypical neurotrophic factor, nerve growth factor (NGF), has been intensively studied for decades, the discovery and characterization of additional such factors has been impeded by their low abundance. Sequence homologies between NGF and the recently cloned brain-derived neurotrophic factor (BDNF) were used to design a strategy that has now resulted in the cloning of a gene encoding a novel neurotrophic factor, termed neurotrophin-3 (NT-3). The distribution of NT-3 messenger RNA and its biological activity on a variety of neuronal populations clearly distinguish NT-3 from NGF and BDNF, and provide compelling evidence that NT-3 is an authentic neurotrophic factor that has its own characteristic role in vivo.

https://science.sciencemag.org/content/sci/247/4949/1446.full.pdf

Neurotrophin-3: a neurotrophic factor related to NGF and BDNF

NT-3, BDNF, and NGF in the developing rat nervous system: parallel as well as reciprocal patterns of expression.

Nerve growth factor, brain-derived neurotrophic factor, and neurotrophin-3 (NT-3) are the three members of the neurotrophin family known to exist in mammals. Recently, a fourth neurotrophin (designated neurotrophin-4 or NT-4), which shares all of the features found in the mammalian neurotrophins, has been identified in Xenopus and viper. We used sequences specific to the Xenopus/viper NT-4 to isolate a neurotrophin from both human and rat genomic DNA that appears to represent the mammalian counterpart of Xenopus/viper NT-4. Human NT-4 as well as a human NT-4 pseudogene colocalize to chromosome 19 band q13.3. Mammalian NT-4 has many unusual features compared to the previously identified neurotrophins and is less conserved evolutionarily than the other neurotrophins. However, mammalian NT-4 displays bioactivity and trk receptor specificity similar to that of Xenopus NT-4.

https://www.pnas.org/content/pnas/89/7/3060.full.pdf

Leonardo Belluscio

Papers

Neurotrophin-3: a neurotrophic factor related to NGF and BDNF

NT-3, BDNF, and NGF in the developing rat nervous system: parallel as well as reciprocal patterns of expression.

Mammalian neurotrophin-4: structure, chromosomal localization, tissue distribution, and receptor specificity.

A simple and efficient non-organic procedure for the isolation of genomic DNA from blood

Mice Deficient in Golf Are Anosmic