Donald J. Sutherland

The photochemical isomerization of dieldrin and endrin and effects on toxicity

The commonly-used insecticides dieldrin (I) and endrin (II) persist in our environment for extended periods (2). Because these insecticides are exposed to sunlight during this time, it is important to determine the identity and toxicity of materials being added to our environment by photochemical pathways. Previous studies have shown that both dieldrin and endrin are readily decomposed by ultraviolet light (3,4). In addition, it was found that one of the ultraviolet decomposition products of dieldrin was the same (by paper and gas chromatography) as the material that was obtained by exposing dieldrin-treated grass to sunlight under natural conditions for several months (4).

Function and operation of the cockroach salivary reservoir

Abstract The duct topography and morphology of the salivary systems of representatives of Blattidae, Blattellidae, and Blaberidae were studied and the amylase activity and factors influencing reservoir filling in Periplaneta americana (L.) investigated. Contrary to previous reports, muscles do serve the salivary reservoir and, depending on the species, act as occlusors and/or compressors. Amylase was found in reservoir contents. Ligation and blocking of duct connexions between the glandular portions and the reservoirs prevented reservoir filling, indicating that the source of reservoir contents is the glandular portion. Reservoir filling depended on the availability of water. It is concluded that the primary function of the salivary reservoir is to store salivary secretion for moistening and digesting food. Secondarily, when water is not available, the reservoir contents serve to partially satisfy the water requirements of the cockroach.

Activity rhythms in the American cockroach, Periplaneta americana☆

Abstract The American cockroach has been the object of much attention with respect ot its biological rhythm of activity. Some authors have indicated the presence of both exogenous and endogenous activity rhythms in adult males. The object of the present study was to determine the variability of such rhythms in a laboratory population, as assayed with two types of recording instruments, one of which was a capacitance monitor. The second and most frequently employed instrument was a running wheel cage. Exogenous (entrained) rhythms were determined in an LD/12 : 12 lighting regimen, and endogenous (free-running) rhythms were determined in constant darkness. Under an LD/12 : 12 lighting regimen, 93·4 per cent demonstrated entrained rhythms or patterns (loose or weak rhythms), and 4·4 per cent displayed apparent random activity. The rhythms and patterns generally were similar to those previously described in the literature, namely the onset of activity occurring within the first few hours of darkness, followed by a relatively quiescent period in the latter part of the dark period and throughout most of the light period. However, a large proportion (31·8 per cent) also possessed a secondary active phase in the first hours of light. Of 75 adult male cockroaches examined in constant darkness, 34·7 per cent exhibited free-running rhythms, 40·0 per cent demonstrated free-running patterns, and 25·3 per cent displayed apparent random activity. The possibility was discussed that a laboratory strain of cockroaches does not show a high percentage of free-running rhythms since the presence of these rhythms is of little survival value. The adult female cockroaches examined did not exhibit activity rhythms that were related to the lighting regimen. A possible relationship of activity to the reproductive cycle was suggested by some experiments, i.e. active when carrying an ootheca and relatively quiescent after deposition. Only virgin females exhibited an entrained activity rhythm similar to that of the adult males.

In vitro transformations of the insect plasmatocyte in some insects

Abstract In vitro transformation of insect plasmatocyte have been studied in physiological saline-versene, tissue culture, and the haemolymph. Transformation of a plasmatocyte into a granular cell can occur either by fragmentation of portions of the cytoplasm or by a gradual rounding-off of the fusiform plasmatocyte. The spherule cell is derived either from a plasmatocyte directly or from a granular cell. Cystocytes are formed from round plasmatocytes or from granular cells. Although gradual transformation of a plasmatocyte and a spherule cell into an adipohaemocyte was not observed, a granular cell was found changing into an adipohaemocyte. Oenocytoids are formed from fusiform plasmatocytes by cytoplasmic fragmentation. Podocytes and vermiform cells are derived from fusiform plasmatocytes by gradual transformation. All these transformations seem to be governed by specific physiological conditions. Oenocytoid- and lamellocyte-like cells are present in the haemolymph of Periplaneta americana (L.). The polymorphic plasmatocyte is the basic type of haemocyte in insects.

Feeding rhythms in the American cockroach, Periplaneta americana☆

Abstract Although much attention has been given to the biological rhythm of activity of the American cockroach, no previous studies on its feeding rhythms have been made. Feeding rhythms were determined with a trophometer, the design and operation of which was based on a food-bearing pendulum whose movement opened and closed an electrical circuit. A total of 64 adult male cockroaches were examined in 12 hr light 12 hr dark for entrained feeding rhythms. Of these individuals, 89·0 per cent exhibited rhythms, 6·3 per cent demonstrated patterns, and 4·7 per cent displayed apparent random feeding activity. The entrained feeding rhythms closely resembled entrained activity rhythms with the onset of feeding occurring soon after the onset of darkness. Some individuals exhibited multiple nocturnal feedings and feeding in the light phase, which was influenced by the presence of a retreat. Of 37 adult males examined for free-running feeding rhythms in total darkness 21·6 per cent exhibited rhythms, 48·6 per cent demonstrated patterns, and 29·8 per cent displayed apparent random feeding. Since the feeding and activity rhythms or patterns were similar to each other with respect to time of onset and percentages of individuals possessing them, the possibility of their interrelationship has been considered.

Experimentally induced tumours in Periplaneta americana L.

Abstract In experiments on the American cockroach the recurrens nerve was severed and the salivary ducts ligatured. The latter operation results in the development of tumours in the salivary acini, reservoir, and associated ducts. The tumours are characterized by rapid cell proliferation and accumulation of inclusion cyst material.

The development of salivary tumours in Periplaneta americana (L.) as induced by duct ligation

Abstract The salivary glands of adult female cockroaches were subjected to duct ligation, unilateral duct ligation, or duct lesion and examined histologically at various times thereafter. Types of effects include (1) dissolution of acini, (2) acinar atrophy, (3) modified acinar atrophy with and without vesicle formation, and (4) haemocytic encapsulation and vesicle formation. Types 3 and 4 involve a proliferation of intercalated cells to form giant cells, which eventually yield the vesicular epithelium. Tumour incidence in acini is greatest after ligation; after duct lesion incidence is highest in the reservoirs. Experimental methods and tumours induced cause increased mortalities.

A hemocytic disorder of the American cockroach, Periplaneta americana☆

Abstract A hemocytic disorder of low incidence has been observed in the American cockroach and is characterized by a massive accumulation of cells in the thoracic hemocoel. Some cells surrounding necrotic areas are definitely hemocytes; dimensions of hemocytes not engaged in encapsulation vary greatly, and it is probable that other cells involved are also hemocytes. The condition was not trausmissible by transplant, possibly as a result of encapsulation by hemocytes of the recipients.

Influence of food on lesions induced by nerve severance in the American cockroach

Abstract Adult Periplaneta americana (the American cockroach) were subjected to nerve severance and maintained on various diets for 2 months to determine the effect of food type on incidence of crop lesions. Incidence was highest among individuals on lab food and lowest on bread crumbs, which formed a more malleable food bolus. Intermediate incidence was observed among those on banana, a diet which was malleable but apparently consumed in much greater quantity.