A New Species of Eimeria from the Golden-Mantled Ground Squirrel, Spermophilus lateralis, in Northern Colorado

Oocysts of Eimeria morainensis n. sp. are described from the golden-mantled ground squirrel, Spermophilus lateralis. in Northern Colorado. The oocysts of E. morainensis are double-walled and subspherical, 20.3 × 19.8 (18.7–26.2 × 17.5–21.2) μm; and the sporocysts are ellipsoid, 12.1 × 6.9 (8.7–13.7 × 6.2–8.7) μm. Oocyst residuum and micropyle are absent, but a polar granule is present. Sporocyst residuum and Stieda body are present. Differences in oocyst characteristics provide the basis for recognition of this new species of Eimeria.     

Ultrastructure of the Amoeboflagellate Tetramitus rostratus1

The life-cycle of the amoeboflagellate Tetramitus rostratus includes amoeboid, cyst, and flagellate stages. The ultrastructure of these three stages is illustrated, with particular emphasis on flagellate morphology. Amoeba morphology is typical of that of limax amoebas. Cysts, forming from trophic amoebas, are enclosed by a wall made up of two layers: ectocyst (ca. 70 nm), and endocyst (200 nm). The wall apparently forms from precursor material present in vesicles in the pre-cyst stage cytoplasm. Flagellate morphology is characterized by a well-defined top-shaped profile, maintained by microtubules under the plasma membrane. The flagellar apparatus or mastigont consists of four flagella, their basal bodies, sheaves of microtubules associated with two of the basal bodies, and several rhizoplasts (periodicity 20 nm). A deep, microtubule-supported, ventral invagination appears to function as a gullet. A small number of mitotic stages observed in amoeboid and flagellate individuals suggests similarity in the division process in both stages: intranuclear mitotic apparatus, nucleolus persisting through mitosis, no centrioles or basal bodies functioning as centrioles, difficulty in resolving chromosomes. The text compares ultrastructures of several amoeboflagellate organisms and evaluates the phylogenetic significance of those features common to different species. On the basis of this study, Tetramitus most closely resembles Naegleria spp.     

Periodic Nocturnal Stomatal Opening of Citrus in a Steady Environment

In a steady environment, leaf stomates of sour orange (Citrus aurantium L.) remained closed in the dark, whereas those of rough lemon (Citrus jambhiri Lush) underwent several 20-minute periods of pronounced opening at intervals of 60–85 minutes. Peak nocturnal opening occurred about 10 minutes after the cycle began, as shown by a change in leaf diffusion resistance from 60 s cm^?1 (closed) to 2 s cm^minus;1 (open). This minimal leaf resistance equals that obtainable in rough lemon in strong illumination (26 kilolux). The transitory stomatal opening detected by leaf resistance measurements was corroborated by measurements of leaf temperature and leaf thickness. During nocturnal opening, leaf temperature was 2°C below the value representing non-cycling periods. Also, minimal leaf thickness coincided with maximal stomatal opening. The triggering mechanism for nocturnal stomatal opening appears to originate within the plant, since the environmental factors of air temperature, humidity, carbon dioxide concentration, and substrate (aerated water culture) were held steady.     

BUOYANCY CONTROL IN AMMONOIDS

A specimen of Buchiceras bilobatum is shown to have been able to maintain neutral buoyancy in water despite the ever increasing weight of epifaunal oysters which it carried on its shell. It is deduced that before settlement of the oyster spat, the camerae of the ammonite contained several grammes of water and that this was slowly pumped out as the oysters grew. Revised calculations on the densities of other ammonoids suggest that the presence of large quantities of liquid in cephalopod camerae was a common occurrence. The significance of this liquid in the growth, mode of life, and evolution of ammonoids is discussed.     

Crystalloid Inclusions in Species of Leucocytozoon,Parahaemoproteus, and Plasmodium*†

Cytoplasmic vacuoles seen in methanol-fixed, Giemsa's-stained ookinetes of Leucocytozoon simondi, Parahaemoproteus fringillae and Plasmodium gallinaceum, when studied with the electron microscope, were found to correspond with crystalloid inclusions of similar structure, particle size, and arrangement. Cytochemical examination of these “crystalloids” revealed their lipid-protein nature. Morphologically similar inclusions were found also in ookinetes of Leucocytozoon ziemanni and Parahaemoproteus velans. In L. simondi, crystalloid is formed rapidly after fertilization, from amorphous electron dense material seen in mature macrogametocytes. The arrangement and distribution of crystalloids in the zygote, ookinete, oocyst, and sporozoite are described. On the basis of differences in structure and particle size, it is proposed that the crystalloid inclusions in Haemosporina be divided into 2 types. Type I—lipid-protein in nature, characterized by electron dense irregularly spherical particles, 25–40 nm in diameter, with individual particles not invested by membrane. Type II—probably virus, characterized by electron dense, irregularly spherical, membrane-bounded particles, with a diameter usually greater than 40 nm.     

DDT inhibits Na<Superscript>+</Superscript>, K<Superscript>+</Superscript>, Mg<Superscript>2+</Superscript>-ATPase in the Intestinal Mucosae and Gills of Marine Teleosts

SODIUM-potassium-activated, magnesium-dependent, adenosine triphosphatase (Na⁺, K⁺, Mg²⁺-ATPase) is widely accepted as an essential factor in sodium transport¹ and observations on fish substantiate this view. There are concurrent increases, for example, of both Na⁺, K⁺, Mg²⁺-ATPase activity and osmoregulatory sodium transport², in the intestinal mucosae^3,4 and the gills^3,5 of euryhaline teleosts during adaptation to seawater. Furthermore, the gills of stenohaline seawater teleosts, which actively secrete sodium, exhibit higher Na⁺, K⁺, Mg²⁺-ATPase activity than the gills of stenohaline freshwater teleosts, which do not actively secrete sodium^3,5. Na⁺, K⁺, Mg²⁺-ATPase therefore seems to be important in maintaining tissue osmolarity well below that of seawater. It is disquieting to report therefore that Na⁺, K⁺, Mg²⁺-ATPase activity in the intestinal mucosae and gills of marine teleosts is inhibited by the organochlorine insecticide DDT. This observation may help to clarify the unexplained sensitivity of teleosts to DDT⁶.     

Restoration of the Immune Response to Sheep Erythrocytes by a Serum Factor

THE immune response of CBA mice to sheep erythrocytes (SRBC) is known to be thymus-dependent because strain members thymectomized during the first few hours of life exhibit a marked inability to respond to this antigen^1,2. Experiments with isoantisera suggested that a cell to cell interaction is involved in this response. Thymus cells per se do not develop into haemolytic plaque-forming cells, but in some, so far obscure, way they cause cells of bone marrow origin to become producers of haemolytic plaques^2,3. A study of spleen cells from neonatally thymectomized (NNT) mice in a tissue culture system indicated that the decreased responsiveness to SRBC is also expressed in vitro. In that case 15×10⁶ NNT spleen cells produced only 500 haemolytic plaques when assayed on day 4 of culture. But when 15×10⁶ thymus cells were added to identical cultures of NNT spleen cells at inception, the number of haemolytic plaque forming cells increased to 2,300 (ref. 4). When an equivalent number of thymus cells alone were incubated with SRBC there was no response.     

Reactivities of Shark 19S and 7S IgM Antibodies to <Emphasis Type="Italic">Salmonella typhimurium</Emphasis>

LOWER vertebrates such as sharks can synthesize humoral antibodies in response to antigenic stimulation with a wide variety of antigens¹. Physicochemical studies have shown that sharks can synthesize both 19S and 7S immunoglobulins and that these two proteins belong to the same immunoglobulin class, which seems to be structurally homologous to IgM as defined for higher animals. Thus the shark immunoglobulins have been designated 19S IgM and 7S IgM^2–4. Because the predominant immunoglobulin (IgG) of most mammals is absent from sharks, the shark monomeric (7S) IgM might be functionally analogous to IgG. One example of the functional differences between IgM and IgG antibodies is the greater reactivity of the former in agglutination and bactericidal reactions^5,6. We have isolated and characterized functionally the relatively high levels of agglutinating antibodies which the nurse shark, Gingly-mostoma cirratum, synthesizes in response to Salmonella typhimurium “O” antigens.