Species-specific markers

Figure 1. Use of 2D gels to study differential protein expression in the parasite Leishmania. Examples inclnde the identification of dmg-resistance proteins (green), strain or species-specific markers (bine), stage-specific proteins (orange), and the effects of host-parasite interactions on both the parasite (teal) and the host (violet).

In the previous experiments, I provided circumstantial evidence to support individual clutch recognition by chemical means. This led to a logical question do egg masses also possess a unique species-specific marker ... 

Figure 19 Sample gel of the results of a PCR. Lane 1 is a 100-bp molecular marker lanes 2-6 are samples. The presence of the top bands (the species-specific endogenous gene) demonstrates that the PCR amplification was successfiil. Lack of the middle band (the introduced effect gene) and the bottom band (the selectable marker gene) in lane 3 indicates that sample is negative for the effect gene. Presence of all three bands in the remaining lanes indicates the samples are positive for the effect gene...

Comments There are several suggested controls for this assay, including use of yeast total RNA as a negative control (check for probe species specificity) and a no RNAse control to determine probe stability. In Fig. 6.3A, the positive control marker lane was produced by addition of R-luc-4 sites or F-luc mRNA only to the assay. Also, optimal times for RNAse digestion will vary from probe to probe. In addition, for maximum sensitivity a probe with high specific activity is preferable (yet still in molar excess to the mRNA). 

Lymphocytes, the effector cells of the acquired immune system, include morphologically indistinguishable T and B cells, the former divided into CD4+ T helper cells and CD8+ cytotoxic T cells. Since the functions of those cell subsets differ so drastically, it became important to develop tools to distinguish them from each other. Efforts to identify cell subsets according to their expression of different surface antigens have been successful, including various Cluster of Determination (CD) markers (Table 23.1). In addition, cross-reactive monoclonal antibodies, and subsequently developed species-specific polyclonal and monoclonal antibodies towards the major histocompatibility complex (MHC) have been used to label cells in circulation and in tissue sections (Table 23.1). 

Ozawa, T. et al.. Identification of species-specific flavone glucosides useful as taxonomic markers in the genus Pyrus, Biosci. Biotechnol. Biochem., 59, 2244, 1995. 

Although CHC profiles tend to be species-specific (reviewed by Howard, 1993 and by Howard and Blomquist, 2005), in many species they cannot always be reliably used as phylogenetic markers - this is particularly the case in many drosophilids (Ferveur, 2005 see also Chapter 7). Examples of qualitative geographic variability in Drosophila CHCs have been given above. In Anopheles mosquitoes, adult CHCs can be used to reliably discriminate between populations in both inter- and intra-specific studies (Phillips et al., 1990 Anyanwu et al., 1993). However, this variability suggests they may not always be reliable for identifying species. 

The evaluations to determine relevant species for toxicity evaluation include various receptor binding assays and tissue cross-reactivity assessments, the later being routinely performed for monoclonal antibody based products (see Chapters 10 and 26). Species specificity can be determined using properly controlled in vitro cell-based response assays, cloning of receptors and ligands to determine compatibility, receptor-based response assays, immunoassays, genomic-based assays, and traditional biochemical-based assays as well as in vivo assessments with validated endpoints and markers for specificity. 

Principle The respiratory burst of phagocytic cells can be assessed by incubating a suspension of the cells in an isotonic solution of the yellow oxidised nitroblue tetrazolium (NBT) dye. During this process, the soluble dye interacts with the cytoplasmic components associating with the oxidant species generated. Although the NBT test is not a specific marker for superoxide production, NBT reduction by activat-... 

The medaka (Oryzias latipes) is a teleost native to Japan, Korea, China, and Taiwan23. Similar to the zebrafish, it produces transparent embryos that allow easy observation and manipulation. Medaka is a popular model organism in Japan and the first fish species in which stable transgenesis was established, it provides some complimentary features to the zebrafish such as adaptation to a wide range of temperatures.22 The identification of sex specific markers, secondary sex characters and a sex determination gene have lead to increasing attraction of the medaka as a model for research on sex determination and differentiation23-28 (photo Andre Kunzelmann, UFZ). 

Recent research has utilized the cell activation marker properties of c-fos, an immediate-early gene, to demonstrate the specificity and pathways of the accessory olfactory system. For example, social odors activate cells in AOB (Schellinck et al. 1993) and, more specifically, central nuclei of the accessory olfactory system regulate species specific mating behavior (Fiber et al. 1993). The complexity of olfactory and somatosensory... 

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