A reliable assessment of the viability of schistosome eggs trapped in host tissues is difficult. The use of a coupling azo dye method for the detection of alkaline phosphatase (A1P) in Schistosoma mansoni ova was found to be a specific and sensitive method for differentiating between viable and dead eggs, and can be used in both immature and mature eggs. In fully developed miracidia within an egg, A1P activity was demonstrated in germ cells and in the sensory endings of the neural cells. The embryonating miracidia displayed A1P activity on the body surface and in von Lichienberg’s envelope. The alkaline phosphatase test for egg viability shows increased sensitivity when compared with the more conventional Oogram and Hatching tests.
Eggs of Huffmanela markgracei sp. n. infected one of three Atlantic sharpnose sharks, Rhizoprionodon terraenovae (Richardson) (Carcharhiniformes: Carcharhinidae) captured by bottom long-line in the northwestern Gulf of Mexico off Padre Island, Texas. Eggs in the skin formed sinuous tracks (1-8 eggs wide; 1-4 eggs deep; 150 eggs/mm2) occupying a swath of the skin 22 cm × 2 cm on the tongue, branchial arches and the dorsal surface of the buccal cavity. Eggs had transverse eggshell ridges (branching and non-branching), had shells that were clear, amber or brown, and measured 90-113 µm (x = 102 ± 4; n = 190) long, 38-54 µm (43 ± 3; 190) wide, 3-5 µm (4 ± 0; 190) in eggshell thickness with protruding polar plugs 8-12 µm (10 ± 1; 190) wide. Apparently fully developed larvae in eggs were 255-335 µm (299 ± 26; 30) long, 8-10 µm (9 ± 1; 30) wide, and in-folded 5-6 (6 ± 0; 30) times. Some of these larvae were emerging from eggs in the skin. The new species differs from congeners by the combination of having a large, spindle-shaped egg, transverse eggshell ridges, an envelope that is smooth, tightly-apposed to the eggshell and surrounds the entire eggshell inclusive of the polar plugs, and a large larva. This is the first report of a species of Huffmanela Moravec, 1987 from a chondrichthyan in the Gulf of Mexico and from a shark not assigned to Carcharhinus.
Twinning has been reported to be much rarer in sea turtles than in freshwater turtles. However, data from sea turtles were inferred from unhatched eggs only. We hypothesized that the difference in twinning events among turtle taxa resulted primarily from the methods used for recording data. In this study, data have been recorded from 727 clutches of eggs of loggerhead sea turtles Caretta caretta laid between 2002 and 2009 at the Pelagie Islands, Italy (n = 36 clutches) and at Dalaman Beach, Turkey (n = 691 clutches). Twin embryos were found in seven out of 12160 unhatched eggs (twinning rate per unhatched egg: 0.058), but not a single case of hatched or emerged twins was recorded in 3571 eggs. The twinning rate recorded, based on post-hoc procedures, did not underestimate the occurrence of the phenomenon: the odds of obtaining a pair of twins in unhatched eggs were as large (0.92 times) as the odds of obtaining a pair of twins in the total eggs. Compared with other loggerhead nesting sites, and other sea turtle species, no statistical differences were found. However, twinning in C. caretta was found to be 6.9 times rarer than in freshwater turtle species.
The reproductive biology (drumming call, mating behaviour, fecundity and egg structure) of Isoperla curtata, an endemic species from the Southern Iberian Peninsula, is described. The male's mating call has a diphasic pattern, with a mean of 17.3 beats per call (range = 8-27; SD = 4.7) and a duration of 792.9 ms per call (range = 228-1312; SD = 307.9). This call differs from that of other species of Isoperla in having two distinct phases with different millisecond intervals, and is species-specific. Mating lasts between 131 and 3864 seconds (mean = 2180.9 s and SD = 1027.8). Since males and females mate more than once (mean number of matings per female was 1.85 and per male 2.25), the species is polyandric and polygynic. The position adopted by the male during mating is different from that described for other stonefly species. Other mating behaviours are interpreted as displacement manoeuvers, tactile stimulation and possibly sexual selection by cryptic female choice. There was a statistically significant correlation between size and the number of matings in females (r = 0.849; p = 0.016), but not in males. Each female laid between one to four egg masses composed of an average of 88.7 eggs. Maximum fecundity was 319 eggs. The mean egg volume was 80.5 × 105 µm3 which is very similar to that of other Isoperla species. An outstanding morphological characteristic of the egg is the lobed outline of the chorion cells.
The eggs of most dactylogyrid and diplectanid monogeneans that infect Acanthopagrus australis are tetrahedral. The adults of larger species deposit more eggs per worm on average in 24h in vitro: Lamellodiscus major (31.7 eggs) = Allomurray-trema rohustum (31.6 eggs) > Haliotrema spariensis (9.6 eggs) > Lamellodiscus squamosus (3.2 eggs). The eggs of L. squamosus (55.9 pm) and H. spariensis (56.4 pm) are smaller than those of L. major (66.1 pm) and A. robustum (63 pm). These eggs are normally shed into the water column. On the other hand, the eggs of Lamellodiscus acanthopagri are a modified T-shape (97.6 pm) and are attached to the gills by a sclerotised, thom-like filament. 1’he parasite can auto-infect the host, but has a low fecundity (0.05 eggs), possibly to prevent lethal parasite burdens.