In insect embryos

Bruce Hammock developed the section on new immunochemical techniques. These chapters describe investigation of disease resistance in plants neuronal development in insect embryos pesticide residue analysis for plant diagnostics and quarantine and the development of a biosensor for applying monoclonal antibodies and microelectronics for environmental analysis. 

The labelled pathways hypothesis, developed by Goodman and co-workers to explain the specific choices of axonal pathways made by growth cones in insect embryos (see Section 3.3.1), predicts the existence of a set of axon guidance molecules with a highly specific and restricted distribution on central and peripheral axonal pathways. 

The cellular studies discussed in Section 3.4.3 provide evidence for a role for glia in guiding axons in insect embryos. To date, however, there are no well-documented examples of molecules that may subserve this function. The case of the DER protein in the Drosophila embryo has been discussed above. Some proteins, such as fasciclin in (see Section 5.1.1) and neuroglian (Section 5.3), are expressed on glia as well as on neurons, but their glial function has not been determined. Oth-... 

A number of proteins have been identified in insect embryos which have structural features suggestive of a role in axon guidance but which, unlike the fasciclins, show a widespread distribution within the nervous system. It should be noted that... 

K. Sander, Pattern specification in the insect embryo. In Cell Patterning. Ciba Foundation Symposium 29, Elsevier, Amsterdam, 1975, pp. 241-263. 

K. Kalthoff, Analysis of a morphogenetic determinant in an insect embryo (Smittia sp., Chironomidae, Diptera). In Determinants of Spatial Organization, S. Subtelny and I. Konigsberg, eds.. Academic Press, New York, 1979, pp. 97-126. 

Larva—Immature form (worm like in insects fishlike in amphibians) of a metamorphic animal which develops from the embryo and differs radically from the adult. 

Effects of ecdysteroids in plants. The discovery that insect hormones occur in plants (31, 32) was a real surprise for endocrinologists. In the meantime more than 100 different phytoecdysteroids have been detected (6). Some of them are identical with insect ecdysteroids, some are unique to plant systems. According to Lafont and Horn (6) phytoecdysteroids have been found in most embryo-phytes, mainly ferns, gymnosperms and angiosperms. Their occurrence in thallophytes has not been reported. The concentration of ecdysteroids in plants may reach or even surpass 1 % of dry weight. Thus ecdysteroids represent the most widespread and quantitatively most abundant family of steroidal animal hormones. 

The excision assay was tested also in two other Drosophila species to determine the functionality of the assay in other insects. Excision occurred in both D. simulans and D. grirashawii at nearly the same rate as observed in D. melanogaster (Table 1). The transposition activity of the P-element in the embryos of these species demonstrates that the excision assay can be employed as a reliable indicator of P-element behavior in other insects. 

In reproductive biology, sialic acid polymers are receiving more and more attention. Polysialic acid with a(2-8)-linkages was found to be expressed on mouse embryos before and after implantation and the neuronal cell adhesion molecule (NCAM), which bears a polysialic acid chain, seems to be involved in cellular interactions in the early mammalian embryo [101,1076]. A similar function is attributed to polysialic acid observed during a short period of the larval stage of Drosophila melanogaster [1077]. It has to be noted that this is the first report on the occurrence of sialic acid in insects. 

Studies in the grasshopper embryo have provided some of the most conclusive evidence of this type. Bastiani and Goodman (1986) showed that the axon of the pCC neuron in the central nervous system (CNS) of this insect embryo grows along a specific axon bundle or fascicle which is pioneered by the axons of the dMP2 and MPl neurons (Fig. 

Many observations show that invertebrate axons are guided, in large part, by factors associated with the substrate in the immediate vicinity of the growth cone. In some situations, such as within the CNS of insect embryos, the axon appears to make highly specific choices of a growth substrate. In other situations, where the options available to a growth cone are limited by the physical availability of alternative routes (such as in the periphery of... 

The primary defect in these mutants may be a failure to fasciculate with other axons and this may result secondarily in cessation of longitudinal extension, as occurs for longitudinally projecting axons in the CNS of insect embryos (see Section... 

Bate, C.M. (1976) Pioneer neurones in an insect embryo. Nature 260 54-56. 

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