Recent advances in the insertion of DNA into higher plant cells

Abstract Recent advances in the insertion, uptake and expression of exocellular DNA in plant protoplasts are reviewed. A comparison is made between plant and mammalian cell systems, in which exogenous DNA is processed during metabolism.     

Development and Ultrastructure of First-Generation Meronts of Sarcocystis cruzi in Calves Fed Sporocysts from Coyote Feces*

SYNOPSIS. The development of Sarcocystis cruzi Hasselmann (syn. S. fusiformis Railliet) meronts was studied in seven 7- to 10-day-old calves killed 4, 7, 11, 15, 22, 25 and 28 days postinoculation (DPI) with 5 × 10⁷ sporocysts from feces of coyotes. No meronts were found 4 and 7 DPI. Young and intermediate meronts with 1–16 nuclei were found in endothelial cells of arteries in mesenteric lymph nodes, but not in kidneys 11 DPI. Mature meronts were noted in endothelial cells of arteries, arterioles, or capillaries of many organs of calves killed 15 to 25 DPI. No first-generation meronts were found 28 DPI. By electron microscopy, all stages of the first-generation merogony were found free within the host cell cytoplasm and not within a parasitophorous vacuole. The appearance of intranuclear spindles preceded the formation of merozoites by endopolygeny. Mature meronts measured 41.0 × 17.5 (34–50 × 15–24) μm, contained ～ 100–350 merozoites, and had 2 to 4 relatively small residual bodies, 2.8 μm in diameter. Merozoites measured 6.3 × 1.5 (5.5–7 × 1 μm) and contained most of the organelles characteristically found in coccidian merozoites. Micropores were observed in merozoites, but not in young and intermediate meronts. Merozoites were seen free in the lumen of blood vessels, in intracellular areas, and free within the host cell cytoplasm.     

Fine Structure of the Oocyst Wall of Eimeria nieschulzi

SYNOPSIS. Oocysts of Eimeria nieschulzi from the laboratory rat, Rattus, norvegicus , were studied by scanning and transmission electron microscopy. Oocysts had a rough outer wall with apparent random depressions. The oocyst wall is composed of 2 layers: an osmiophilic outer layer consisting of a rough external and smooth internal surface, and a relatively thick, electron-lucent inner layer. The outer layer is composed of a dense, coarsely granular matrix. The inner layer consists of homogeneous fine granular material interspersed with coarse osmiophilic granules and contains one closely applied membrane on the outermost surface. Several raised lenticular areas are seen on the coarse outer surface of the inner layer. These layers are 102 (75–128) and 176 (135–204) nm thick, respectively.
The sporocyst wall is thin, consisting of 3 to 4 unit membranes, and measures 27 (18–34) nm thick.     

Comparative morphology of the carpel in the Liliaceae: Baeometra, Burchardia and Walleria

The pistils in Baeometra, Burchardia and Walleria ate tricarpellate, and their ovules are mostly bitegmic. Baeometra has free styles and deep septal invaginations between the carpels. Its pistil is innervated by three dorsal bundles, three compound septal bundles (each of which may divide into two simple septal bundles above), six placental bundles, and six adjoining auxiliary placental bundles. The pistil of Burchardia resembles that of Baeometra , except that there are six simple septal bundles throughout and no auxiliary placental bundles. In Walleria the wings of adjoining carpels are completely fused (except for rare septal glands); there is a single compound style; additional vascular tissue is present in the central axis of the pistil up to the lowermost ovules; the carpels are fused with the floral cup above the base of the locules; and raphide idioblasts are present. Walleria has six "ventral" bundles, each of which appears to be the fusion product of a placental bundle with a simple septal bundle. Tribal affinities of these genera are discussed.     

An Ultrastructural Study of First- and Second-Generation Merogony in the Coccidian Sarcocystis tenella1

ABSTRACT. Sporocysts of the coccidian Sarcocystis tenella were originally isolated in the feces of a coyote. Sporocysts used for inoculation of lambs were obtained from experimentally infected dogs. At 14, 16, and 19 days postinoculation (DPI) of lambs with the sporocysts, various developmental stages of first-generation meronts were found within cells located between the endothelium and internal elastic membrane of mesenteric arteries. At 19, 21, and 25 DPI, second-generation merogony occurred in cells associated with capillaries and arterioles of kidney glomeruli and convoluted tubules. Meronts of both generations were bounded by a double pellicular membrane and were situated free in the host cell cytoplasm. Merozoites formed by endopolygeny that involved multiple intranuclear spindles of a single, large irregular nucleus. First-generation meronts measured 22.6 × 17.1 μm (19–28.7 × 7.5–24 μm) and contained 120–240 merozoites, which measured 7.1 × 1.6 μm (4.8–7.5 × 1.3–1.8 μm). Corresponding values for second-generation meronts were 13.2 × 9.2 μm (8.3–15 × 7–13.5 μ), 32–80, and 5.8 × 1.7 μm (5.6–6.2 × 1.4–2.2 μm).     

Comparative morphology of the carpel in the Liliaceae: Uvularieae

Three genera of the Uvularieae (Kreysigia, Schelhammera, Uvularia) have tricarpellate, syncarpous pistils. Ventral bundles (presumably the united simple septal and placental bundles of a carpellary wing) may be present in Kreysigia and Schelhammera. In Kreysigia the two presumptive ventral bundles from adjoining carpels are fused basipetally in each septum. The septal bundles of the other two genera are either simple (Schelhammera) or in part compound (united) below and simple (separate) above (Uvularia) , hence fused acropetally. In Uvularia , the dorsal bundle of the carpel and the median bundle of the tepal are uniquely tripartite and probably homologous. No raphides were found in the carpels of these genera.     

Alternative seed defence mechanisms in a palo verde (Fabaceae) hybrid zone: effects on bruchid beetle abundance

Abstract.

• 1 We asked three questions about the patterns of relative abundance of insect herbivores across host plant taxa at a palo verde hybrid zone. (1) What is the morphological structure of the hybrid zone and does this suggest a certain pattern of introgression? (2) How are putative parental seed defence mechanisms expressed in hybrid plants? (3) Do ovipositing females prefer host plant taxa on which their offspring have best survivorship?
• 2 Morphologically, hybrids were either intermediate or tended to resemble one parental species. Previous studies have suggested that unidirectional introgression results in loss of parental defence mechanisms against herbivores. Hybrid plants in general lacked seed coat resistance and early pod abscission which are known to act as plant defence mechanisms against bruchid beetles in the parental palo verde trees.
• 3 All other sources of bruchid mortality that we examined did not vary across parental and hybrid taxa, with the possible exception of egg parasitism which occurred at a lower frequency on one parental palo verde species.
• 4 Thus, survivorship of bruchid offspring should be greater on hybrid palo verdes.
• 5 Patterns of egg densities suggested that females may prefer hybrid hosts in some years but not others. An oviposition choice experiment conducted in the field, however, showed bruchids have no preference for hybrids over one of the parental species.
• 6 These results suggest that some insect herbivores may have higher densities on hybrid host plants because they are less resistant.

     

Hammondia pardalis sp. n. (Sarcocystidae) from the Ocelot, Felis pardalis, and Experimental Infection of Other Felines

Synopsis.
Hammondia pardals sp. n. (Eimeriorina: Sarcocystidae) from Panama Canal Zone is described as an obligate heteroxenous coccidian, with felids as the final host and laboratory mice as the experimental intermediate host. Ovoid oocysts. measuring 40.8 (36–46) × 28.5 (25–35) m. are shed unsporulated. Oocysts were infective only for the intermediate host. the laboratory mouse, Mus musculus , and the intracellular cysts were infective only for felids. Attempted passage of tissue cysts from mouse to mouse was unsuccessful.
Mice fed 5 × 10⁴ sporulated oocysts were found to harbor small intracellular cysts, 13–16 × 10–15 m, in the mesenteric lymph nodes, lungs, and intestinal submucosa 15 days postinfection. The meronts in these early cysts were stubby and measured 3 × 6 m. The prepatent period in the felids was 5 to 8 days and the patent period 5–13 days. Experimental infections of definitive hosts were successful with 6/6 domestic laboratory-reared kittens, Felis catus ; 5/5 ocelots, F. pardalis ; and 1/1 jaguarundi, F. yagouaroundi. None of the exposed raccoons, Procyon lotor , shed oocysts.     

Comparative morphology of the carpel in the Liliaceae: Wurmbaeae

The two genera of Buxbaum's tribe Wurmbaeae, Anguillaria and Wurmbea , have multiovulate carpels. There are deep septal indentations between the carpels of Anguillaria , but the wings of adjoining carpels are fused to solid septa in most species of Wurmbea. In Anguillaria the carpels have open sutures or prominent commissural markings; in Wurmbea the carpels generally lack these characteristics, and some species have a vascularized, columella-like axis in the centre of the pistil. In both genera there are a dorsal bundle, lateral bundles, and two placental bundles in each carpel. At the inner edge of the septum there are one or two septal bundles in Anguillaria and one or none in Wurmbea. The ovules are monotegmic, the integument and funiculus being partly fused in Anguillaria and mostly fused in Wurmbea. An obturator is present in Anguillaria but absent from most species of Wurmbea.