Richard D. Karp

Immunity in a Social Insect

Abstract Although pathogens appear to have exerted significant selective pressure on various aspects of sociality, mechanisms of disease resistance in the social insects are poorly understood. We report here on an immune response to infection by the dampwood termite, Zootermopsis angusticollis. Nymphs immunized with an injection of 7.6×107, 7.6×105, or 7.6×104 cells/ml glutaraldehyde-killed solution of the bacterium Pseudomonas aeruginosa had significantly higher survivorship than controls following a challenge with a lethal concentration of active bacteria. Similarly, nymphs exposed to a 9×10–1 spores/ml suspension of the fungus Metarhizium anisopliae had higher survivorship than controls after a challenge with a lethal concentration of spores. Prior exposure to a pathogen thus conferred upon termites a degree of protection during a subsequent encounter with the same pathogen. This represents the first demonstration of immune function in vivo in a social insect.

Induction of specific humoral immunity to soluble proteins in the American cockroach (Periplaneta americana): II. Nature of the secondary response

Abstract Adult male American cockroaches ( Periplaneta americana ) generated a specific protective response when injected with soluble protein toxins. This response developed over a period of time, peaking within 2 weeks and then gradually subsiding by the fifth week. Specificity of this reactivity was demonstrated by the fact that immunized animals were only protected against the original immunizing toxin, and not to a heterologous toxin. Passive transfer studies revealed that protection could be transferred to virgin animals with cell-free immune hemolymph. Thus, this advanced invertebrate is capable of generating a specific adaptive humoral immune response to these soluble proteins.

Genetics Content in Introductory Biology Courses for Non-Science Majors: Theory and Practice

lives requires greater attention to the study of genetics in our educational system. To understand the significance of the rough draft of the human genome, the related benefits and risks of gene therapy, and the increasing complexity of gene–gene and gene–environment interactions, the public must understand basic principles of genetics, including human genetics.The National Science Education Standards, developed by the National Research Council, recommend that the concept of inheritance be introduced in grades kindergarten (K)–4 and the basic principles of heredity and genes in grades 5–8. The standards for grades 9–12 concentrate on the molecular basis of inheritance, including DNA structure and function, genetic change, and variation (NRC 1996). No similar benchmarks exist for the genetics and human genetics curricula offered at collegiate institutions. Medical schools have received more attention in this regard than have college and university undergraduate courses. Twenty years ago, a noteworthy study of 103 of the 107 medical schools then operating in the United States analyzed the medical genetics courses in terms of content, duration, responsible department, and primary discipline of the instructor (Childs et al. 1981). The authors concluded that human genetics had not found a comfortable niche in medical schools. Shortly thereafter, Goodman (1982) suggested implementation of a core curriculum in genetics and clinical genetics and further proposed establishment of a Genetics Education Task Group to coordinate the process. Much later, in 1995, the Information and Education (I&E) Committee of the American Society of Human Genetics (ASHG) submitted a report outlining a core curriculum in medical genetics for medical school (Friedman et al. 1995). Studies conducted at the precollege level and in medical schools left the undergraduate years unaddressed. In 1999, ASHG began to address this deficiency by offering a workshop on undergraduate genetics education at its annual meeting (Bender et al. 1999). Catalyzed in part by the positive reception of this workshop, the I&E Committee appointed a subcommittee on undergraduate genetics education to develop a set of content recommendations for institutions of higher education (Paula Gregory, ASHG I&E chairperson, personal communication, 1999). The committee, which comprises the first eight authors of this article, represents a wide variety of educational and professional backgrounds, including undergraduate biology education, clinical genetics, nursing, genetics education, and more than 100 years of cumulative teaching experience.

Effect of gender on the inducible humoral immune response to honeybee venom in the american cockroach (Periplanetaamericana)

It is well known that in higher animals, the female of the species usually possesses a superior immune response to that of the male. We investigated the possibility that this rule of nature might also be true amongst the invertebrates. Adult female American cockroaches (Periplaneta americana) were immunized with Honeybee venom, and their responses were compared to that of the adult male. The female primary response was found not only to be enhanced, but prolonged as compared to the male. The response was also specific and demonstrated long-term immunological memory. Thus, the humoral immune response of this advanced invertebrate shares yet another characteristic common to higher vertebrates, since the female of the species demonstrated much better immune responsiveness than the male.

THE ULTRASTRUCTURE OF COELOMOCYTES OF THE SEA STAR DERMASTERIAS IMBRICATA

It has been previously reported that the sea star, Derniasteria.s inibricata, possesses a true adaptative cehl-nuediated immune response, as reflected by the specific chronic rejection of integumentary allografts (Karp and Hildemann, 1976). The reaction appears to be nuediated by infiltration by phagocytic cells. Since the predominant phagocyte in the sea star is the coehomic amoebocyte ( Boolootian and Giese, 1958 ; Endean, 1966) , this cell may mediate the graft reaction. This hypothesis is supported by the recent report of Bertheussen ( 1979) that phagocytic amoebocytes of the sea urchin Strong ylocentrotus droebachiensis demonstrate in vitro cytotoxic reactions against both allogeneic and xenogeneic echinoid cells. Although several excellent studies characterize the coelonuocytes of holothurians and echinoids (Hetzel, 1963; Johnson, 1969a, b, c; Chien et al., 1970; Fontaine and Lambert, 1973, 1977; Bertheussen and Seljelid, 1978; Bertheussen, 1979), only sparse information deals with asteroids. To further understand the imnuunologic capacities of the sea star, Dermasterias, and to conupare them with those of other animals, we have characterized the ultrastructure of the coeoloniic anioebocyte and have reaffirmed its phagocytic role. Ultrastructural observations on Tiede manns bodies were also made to deternuine whether or not the cells of this organ participate in phagocytic activities. We experimented on aninuals stressed by inter mittent extraction of coelomic fluid to follow the recovery of coehomocytes, and to determine whether or not this recovery is due to cell division in the circulating coelomic fluid.

Cell-mediated Immunity in Invertebrates

D uring evolution, vertebrates have made a major biological commitment to the development of an inducible immune response. This complex system is important for the survival of vertebrate species in a naturally hostile environment. Some scientists have argued that for invertebrates this same selective pressure resulted in a different life strategy: short lifespans and rapid reproduction. These scientists view invertebrates as too unsophisticated physiologically to mount specific adaptive defense mechanisms to meet microbial or toxic threats. However, recent evidence indicates that these so-called primitive animals are unexpectedly complex genetically and that many of the old generalizations concerning their metabolic limitations do not hold true. Biologists are finally starting to appreciate the difficulties in generalizing about invertebrate species, which have tremendous diversity not only in biological form but also in lifestyles. The inducible or adaptive immune response as defined in vertebrates consists of two major facets: the humoral response, which is mediated by circulating antibodies, and the cellmediated immune response (CMI), which is mediated by lymphocytic cells. Both of these responses are characterized by specificity and the

An inducible humoral factor in the American cockroach (Periplaneta americana): Precipitin activity that is sensitive to a proteolytic enzyme

Abstract The humoral factor induced in the American cockroach, Periplaneta americana, by the soluble protein venoms, honeybee venom (HBT) and Western cottonmouth moccasin venom (CMV), was shown to behave like a precipitating antibody-like molecule, since it formed specific precipitin bands with homologous antigen in Ouchterlony gels. In addition, the humoral factor was demonstrated to be protein in nature, since it was sensitive to the proteolytic enzyme trypsin. Hyperimmune hemolymph treated with trypsin no longer passively protected animals from the lethal effects of HBT, and lost its ability to form precipitin bands with the antigen in Ouchterlony gels.

Ontogeny of the invertebrate humoral immune response: Studies on various developmental stages of the American cockroach (Periplaneta americana)

Earlier studies revealed that a specific adaptive humoral immune response can be induced in the American cockroach (Periplaneta americana) to the soluble protein complex, Honeybee venom (HBT). We have undertaken a series of ontogenetic studies to determine if there are differences between the protective responses of roaches representing different developmental stages. Our results indicated that the response to HBT in the immature cockroach (nymphs weighing 200-500 mg) was characterized by a significant lag period before immune protection began to develop. However, by the second week of the response, reactivity was comparable to that of the adult. Old adult male roaches (animals 5 months into adulthood) displayed a significant decline in reactivity during the early phases of the response in comparison to younger adults, and in general, appeared to be less vigorous in generating protection. Both the nymph and old adult roaches demonstrated good secondary responsiveness. The results from these experiments indicated that the developmental stage of the roach could be directly correlated to the degree of immunocompetency possessed by the animal. This is similar to the ontogenetic sequence typically found for immune reactivity in vertebrates.

Stimulation of hemocyte proliferation in the American cockroach (Periplaneta americana) by the injection of Enterobacter cloacae

Abstract Previous studies have determined that the American cockroach (Periplaneta americana) generates true cell-mediated immunity as well as adaptive humoral immunity. A basic characteristic of immune responses of higher animals is the proliferation of responding cell types following antigenic stimulation. To determine if circulating hemocytes of Periplaneta were capable of in vivo cell division, animals were injected with 108 cells/gm body weight of fixed Enterobacter cloacae. This resulted in a depletion of circulating hemocytes by 12 h after injection as compared to saline-injected controls. Flow cytometry (FC) was used to determine if circulating cells were dividing in stimulated animals. Hemocytes from bacteria or saline-injected animals were collected at various times after injection, fixed and stained with propidium iodide, and analyzed by FC. Using a mathematical model to assign cells to appropriate stages of the cell cycle, the results indicated that animals injected with bacteria have a significantly greater percentage of hemocytes in S and G 2 M phases than saline-injected controls. This response was observed as early as 1 h after injection, and continued for several weeks after bacteria-injected animals had returned to normal cell numbers. This is the first evidence suggesting that circulating hemocytes can divide in vivo in Periplaneta americana following antigenic stimulation.

The humoral immune response in the american cockroach, Periplanetaamericana: Reactivity to a defined antigen from honeybee venom, phospholipase A2

Our previous experiments demonstrated that honeybee venom could induce a specific, adaptive humoral immune response in the American cockroach. Since honeybee venom is a complex substance made up of several proteins, a more defined antigen is needed for future characterization studies. One of the components of bee venom, phospholipase A2 (PA2) was found to be highly lethal and immunogenic in the roach. Roaches injected with PA2 generated a specific primary response that developed over a period of time, peaking within 10 days, and then gradually subsiding by the fifth week. Specificity of this response was demonstrated by the fact that immunized animals were protected against the original immunizing PA2, but not to PA2 from a heterologous source. In addition, a secondary response could be induced with PA2, demonstrating the existence of immunologic memory. Thus, we established that PA2 could induce as good, if not better, humoral responsiveness as whole bee venom, and therefore could be utilized as a more defined antigen in studies designed to characterize the inducible humoral factor in the roach.