Taxonomy and Review of the Coccidian Genus Cryptosporidium (Protozoa,Apicomplexa)1

Reports of Cryptosporidium in various hosts and cross-transmission experiments are reviewed. Cryptosporidium has been found in mammals (Primates, Artiodactyla, Perissodactyla, Carnivora, Lagomorpha, and Rodentia), birds, reptiles, and fish. The only cross-transmission attempts that have been made have been from mammals to other mammals and to a few birds. Names have been given to 19 “species,” but it is concluded that only four of these should be considered valid at present. These are: C. muris Tyzzer, 1907 in mammals, C. meleagridis Slavin, 1955 in birds, C. crotali Triffit, 1925 in reptiles, and C. nasorum Hoover, Hoerr, Carlton, Hinsman & Ferguson, 1981 in fish.     

The diet of feral cats on islands: a review and a call for more studies

Cats are among the most successful and damaging invaders on islands and a significant driver of extinction and endangerment. Better understanding of their ecology can improve effective management actions such as eradication. We reviewed 72 studies of insular feral cat diet from 40 islands worldwide. Cats fed on a wide range of species from large birds and medium sized mammals to small insects with at least 248 species consumed (27 mammals, 113 birds, 34 reptiles, 3 amphibians, 2 fish and 69 invertebrates). Three mammals, 29 birds and 3 reptiles recorded in the diet of cats are listed as threatened by the IUCN. However, a few species of introduced mammals were the most frequent prey, and on almost all islands mammals and birds contributed most of the daily food intake. Latitude was positively correlated with the predation of rabbits and negatively with the predation of reptiles and invertebrates. Distance from landmass was positively correlated with predation on birds and negatively correlated with the predation of reptiles. The broad range of taxa consumed by feral cats on islands suggests that they have the potential to impact almost any native species, even the smallest ones under several grams, that lack behavioral, morphological or life history adaptations to mammalian predators. Insular feral cat??s reliance on introduced mammals, which evolved with cat predation, suggests that on many islands, populations of native species have already been reduced.     

A phylogenetic survey of biliary lipids in vertebrates

Biliary lipids (bile salts, phospholipids, cholesterol, plant sterols) were determined in 89 vertebrate species (cartilaginous and bony fish, reptiles, birds, and mammals), and individual phospholipid classes were measured in 35 species. All samples contained conjugated bile salts (C(27) bile alcohol sulfates and/or N-acyl amidates of C(27) and/or C(24) bile acids). Phospholipids were generally absent in the bile of cartilaginous fish and reptiles and were present in low amounts relative to bile salts in bony fish and most birds. In mammals, the phospholipid-bile salt ratio varied widely. The bile from species with low biliary phospholipid-bile salt ratios often contained a high proportion of sphingomyelin, confirmed by HPLC-MS. In species with a high phospholipid-bile salt ratio, the predominant biliary phospholipid was phosphatidylcholine (PC). The phospholipid-bile salt ratio correlated weakly with the calculated weighted hydrophobic index value. Cholesterol was present in the bile of virtually all species, with plant sterols uniformly being present in only trace amounts. The cholesterol-bile salt ratio tended to be higher in mammals than in non-mammals, but bile of all species was unsaturated. Thus, most nonmammalian vertebrates have relatively low levels of biliary phospholipid and cholesterol, suggesting that cholesterol is eliminated predominantly as bile salts. Mammals have a higher phospholipid and cholesterol to bile salt ratio, with the dominant phospholipid being PC.     

The scaling and temperature dependence of vertebrate metabolism

Body size and temperature are primary determinants of metabolic rate, and the standard metabolic rate (SMR) of animals ranging in size from unicells to mammals has been thought to be proportional to body mass (M) raised to the power of three-quarters for over 40 years. However, recent evidence from rigorously selected datasets suggests that this is not the case for birds and mammals. To determine whether the influence of body mass on the metabolic rate of vertebrates is indeed universal, we compiled SMR measurements for 938 species spanning six orders of magnitude variation in mass. When normalized to a common temperature of 38 degrees C, the SMR scaling exponents of fish, amphibians, reptiles, birds and mammals are significantly heterogeneous. This suggests both that there is no universal metabolic allometry and that models that attempt to explain only quarter-power scaling of metabolic rate are unlikely to succeed.     

The fastest contracting muscles of nonmammalian vertebrates express only one isoform of the ryanodine receptor.

The skeletal muscles of chickens, frogs, and fish have been reported to express two isoforms (alpha and beta) of the sarcoplasmic reticulum calcium release channel (ryanodine receptor or RYR), while mammals express only one. We have studied patterns of RYR isoform expression in skeletal muscles from a variety of fish, reptiles, and birds with immunological techniques. Immunoblot analysis with a monoclonal antibody that recognizes both nonmammalian RYR isoforms and a polyclonal antibody specific to the alpha isoform show two key results: (a) two reptilian orders share with mammals the pattern of expressing only the alpha (skeletal) RYR isoform in skeletal muscle; and (b) certain functionally specialized muscles of fish and birds express only the alpha RYR isoforms. While both isoforms are expressed in the body musculature of fish and birds, the alpha isoform is expressed alone in extraocular muscles and swimbladder muscles. The appearance of the alpha RYR isoform alone in the extraocular muscles and a fast-contracting sonic muscle in fish (toadfish swimbladder muscle) provides evidence that this isoform is selectively expressed when rapid contraction is required. The functional and phylogenetic implications of expression of the alpha isoform alone are discussed in the context of the mechanism and evolution of excitation-contraction coupling.     

Polypeptide YY- and neuropeptide Y-immunoreactive cells and nerves in the endocrine and exocrine pancreas of some vertebrates: An onto- and phylogenetic study

Summary The occurrence of polypeptide YY- and neuropeptide Y-immunoreactive cells and nerves in the pancreas of some species from all the eight main vertebrate groups (cyclostomes, cartilaginous fish, bony fish, amphibia, reptiles, birds, and mammals) was investigated. In addition, an ontogenetic study of these neurohormonal peptides was performed, using the rat pancreas. The distribution of these two peptides was compared with that of the structurally closely related pancreatic polypeptide.Polypeptide YY-immunoreactive cells were found to occur in the endocrine pancreas and neuropeptide Y-immunoreactivity was observed both in neurons and nerve fibres. The polypeptide YY-immunoreactive cells were limited to mammals and reptiles only. Neuropeptide Y-immunoreactive neurons and nerves were observed in reptiles, birds, and mammals only. One reptilian species (out of three) and one mammalian (out of six) failed to show any kind of immunoreactivity for the polypeptide or neuropeptide. Pancreatic polypeptide-immunoreactive cells were found in all the species examined except in the hagfish islet.In rat foetuses, polypeptide YY-immunoreactive cells and neuropeptide Y-immunoreactive nerve elements were first demonstrated at the seventeenth day of gestation, whereas pancreactic peptide-immunoreactive cells did not appear until postnatally, namely in two day-old rats. The polypeptide-containing cells, a new cell type in the endocrine pancreas, are rare. In contrast to the pancreatic peptide cells, they do not seem to have any kind of regional distribution.     

Morphologic, host specificity, and genetic characterization of a European Cryptosporidium andersoni isolate

This study was undertaken in order to characterize a Cryptosporidium muris-like parasite isolated from cattle in Hungary and to compare this strain with other Cryptosporidium species. To date, the large-type oocysts isolated from cattle were considered as C. muris described from several mammals. The size, form, and structure of the oocysts of the Hungarian strain were identical with those described by others from cattle. An apparent difference between the morphometric data of C. muris-like parasites isolated from cattle or other mammals was noted, which is similar in magnitude to the differences between Cryptosporidium meleagridis and Cryptosporidium felis or between Cryptosporidium serpentis and Cryptosporidium baileyi. The cross-transmission experiments confirmed the findings of others, as C. muris-like oocysts isolated from cattle fail to infect other mammals. The sequence of the variable region of small subunit (SSU) rRNA gene of the strain was 100% identical with that of the U.S. Cryptosporidium andersoni and C. andersoni-like isolates from cattle. The difference between the SSU rRNA sequence of bovine strains and C. muris is similar in magnitude to the differences between C. meleagridis and Cryptosporidium parvum anthroponotic genotype or between Cryptosporidium wrairi and C. parvum zoonotic genotype. Our findings confirm that the Cryptosporidium species responsible for abomasal cryptosporidiosis and economic losses in the cattle industry should be considered a distinct species, C. andersoni Lindsay, Upton, Owens, Morgan, Mead, and Blagburn, 2000.     

Putative prion protein from Fugu (Takifugu rubripes)

Prion proteins (PrP) of mammals, birds, reptiles and amphibians have been successfully cloned, expressed and purified in sufficient yields to enable 3D structure determination by NMR spectroscopy in solution. More recently, PrP ortholog genes have also been identified in several fish species, based on sequence relationships with tetrapod PrPs. Even though the sequence homology of fish PrPs to tetrapod PrPs is below 25%, structure prediction programs indicate a similar organization of the 3D structure. In this study, we generated recombinant polypeptide constructs that were expected to include the C-terminal folded domain of Fugu-PrP1 and analyzed these proteins using biochemical and biophysical methods. Because soluble expression could not be achieved, and refolding from guanidine-HCl did not result in a properly folded protein, we co-expressed Escherichia coli chaperone proteins in order to obtain the protein in a soluble form. Although CD spectroscopy indicated the presence of some regular secondary structure in the protein thus obtained, there was no evidence for a globular 3D fold in the NMR spectra. We thus conclude that the polypeptide products of the fish genes annotated as corresponding to bona fide prnp genes in non-fish species cannot be prepared for structural studies when using procedures similar to those that were successfully used with PrPs from mammals, birds, reptiles and amphibians.     

Heart rate response to gentle handling of frog and lizard

Heart rate was counted telemetrically in lizards (Iguana iguana) and frogs (Rana catesbeiana and Rana pipiens) to estimate their response to gentle 1-min handling. The animals were kept at steady body temperatures of ca. 28 degrees C (lizards), and 24 degrees C (frogs). Handling increased the heart rate of lizards from ca. 70 to 110 beats per min immediately during and after handling and this tachycardia decreased in ca. 10 min. Similar handling did not modify significantly the frogs' heart rates. Although the absence of a response to mild stress is not synonymous with the absence of emotion, the absence of handling-tachycardia in frogs and its presence in lizards (as well as in mammals and birds), together with the emotional fever in mammals, birds, and reptiles, but not frogs or fish as reported in the literature, might suggest that 'emotional' response to stress emerged in phylogeny between amphibians and reptiles.     

Body cavities in fishes

Four types of body cavity arrangement were found in 20 species of fish (see Materials and Methods). The body cavities of fishes were also compared with those of mammals and birds. It was concluded that higher vertebrates utilized only the Tinca type for their evolution, while the other types were dead-end evolutionary forms which terminated at fish level, or possibly with amphibians and reptiles. The necessary research in these groups still remains to be done.     

Feeding habits of invasive American mink (Neovison vison) in northern Germany—potential implications for fishery and waterfowl

In order to collect ecological data of invasive American mink (Neovison vison) at a fishpond area in northeastern Germany, we conducted a telemetry study in which 14 mink were radio-tracked. During this project, 2,502 scats from radio-tracked individuals were collected in the period from October 2003 to October 2005. Investigated mink principally prey on fish, small mammals and birds (eggs inclusive), whereas amphibians, reptiles and invertebrates were caught infrequently. Analysing mink scats of different seasons, we found significant seasonal variations of diet composition. In spring, fish, mammals and birds were hunted in similar amounts. During summer, birds made up the main part of the diet followed by mammals. In autumn, the proportion of birds in the mink diet decreased, whereas fish gained in importance. This trend continued during the winter period, when mink preyed almost exclusively on fish. Amphibians, crustaceans, insects, molluscs and reptiles were found only occasionally in scat samples. Among birds, the mink preyed mainly on the Eurasian Coot (Fulica atra) followed by the Mallard (Anas platyrhynchos). Mammalian prey was clearly dominated by the water vole (Arvicola terrestris) and among fish, mink hunted especially perch (Perca fluviatilis), roach (Rutilus rutilus) and carp (Cyprinus carpio). Results clearly demonstrate that mink is an opportunistic predator, which hunts its prey according to availability and vulnerability, respectively. Despite the high portions of fish in their autumn and winter diet, the economic damage caused by mink seems to be negligible. However, high predation rates on birds during the breeding season indicate a potential negative impact of mink on waterfowl.     

Effect of pH, temperature and incubation period on the study of intrinsic innervation of various organs by thiocholine technique in certain vertebrates.

The adrenergic fibres can be demonstrated if the optimal time and temperature are maintained. The cholinergic fibres were demonstrated at pH 5.2, incubation period l4h and temperature 37 degrees C. To ascertain the cholinesterase activity in tongue, heart, lung(birds, mammals and reptiles), gizzard and proventriculus (birds) and penis (rat and embryo of squirrel), pH 4.9, 16h incubation and temperature 37 degrees C, were quite suitable. It was possible to demonstrate the intrinsic innervation in tongue, lung, heart (mammals, birds and reptiles), gizzard and proventriculus (birds) and penis (rat and embryo of squirrel), at pH 5.2, 20h incubation and temperature 40 degrees C.     

Plasma zinc concentrations in snakes and other vertebrates correlate with specific zinc-binding plasma proteins

We have demonstrated that snakes and some other reptiles normally possess high plasma zinc concentrations. These levels are similar to those measured in teleost fish. Plasma zinc levels in the range of snakes and teleosts have been shown to be toxic to crocodilians and mammals. Zinc has been shown to bind to a specific protein in albacore and winter flounder serum. Previous experiments suggested a similar protein in snake plasma. Western blot techniques were used to search for proteins capable of binding large quantities of zinc with high affinity in the plasma of a wide range of vertebrate species. These data were compared to plasma zinc concentrations measured by atomic absorption spectrophotometry. A correlation between high zinc levels and the presence of specific zinc-binding proteins different from mammalian albumin was observed. Snakes and teleost fish demonstrated both very high plasma zinc concentrations and a zinc-binding protein. Teleosts and snakes have significantly higher levels of plasma zinc than birds and mammals.     

The Evolution of Reptilian Social Behavior

Reptiles display a diversity of behavior that is reflectiveof their evolutionary heritage from fish and amphibians andtheir ancestral contribution to the diversity found in birdsand mammals. Much of the behavior observed in reptiles seemsspecific to the ecological setting within which they live. Asa result, a diversity of behavior is found in each of the groupsof modern reptiles. Recent studies on the social behavior oflizards have proved them capable of a variety of behavioralpostures, sequences, and sociality that exceeds that found insome mammals and birds. While many species of lizards are territorial,others are hierarchial and some have harems. For all those territorialspecies studied, crowding results in increased social interaction,increased aggression, and a switch to hierarchial behavior. While smell and sound may be important stimuli for social behaviorin some reptiles, posture, actions, and especially color appearto be most important in diurnal lizards. Temperature and energystudies suggest that the large extinct dinosaurs probably foughtconsiderably less than commonly portrayed in movies and stories,but were also probably much more brightly colored than commonlyshown in reconstructions.     

Relationships among nutrition and reproduction and relevance for wild animals

This review discusses aspects of feeding ecology, nutrition, and dietary husbandry that are particularly relevant to reproductive success in wild animals. Emphasis has been placed on recently published literature. Special attention has been given to requirements for energy and protein and the unique roles of essential amino acids, essential fatty acids, calcium, phosphorus, zinc, copper, selenium, and vitamins A, C, D, and E. Information has been drawn from research with mammals, birds, reptiles, amphibians, and fish, including the domestic and laboratory species that play such a large role in elucidating mechanisms connecting nutrition and reproduction. Zoo Biol 23:475–487, 2004. © 2004 Wiley-Liss, Inc.     

Do mammals,birds, reptiles and fish have similar nitrogen conserving systems?

Comparative physiological studies are a powerful tool for revealing common animal adaptations. Amino acid catabolism produces ammonia which is detoxified through the synthesis of urea (mammals, some fish), uric acid (birds), or urea and uric acid (reptiles). In mammalian herbivores and omnivores, urea nitrogen is salvaged by a series of steps involving urea transfer into the intestine, microbial mediated urea hydrolysis with synthesis of amino acids utilizing the liberated ammonia and transfer of the amino acids back to the host. A similar series of steps occur in omnivorous/granivorous and herbivorous birds, although in this case urine, containing uric acid, is refluxed directly into the intestine where microbes degrade the uric acid and utilize the liberated ammonia for amino acid synthesis. These amino acids are transferred back to the host. In reptiles and ureotelic fish not all of these steps have been experimentally confirmed. Reptiles like birds, reflux urine into the intestine where it is exposed to the microflora. However, the capacity of these microbes to breakdown the uric acid and urea and utilize ammonia for amino acid synthesis has not been documented. Ureotelic fish transfer urea into the intestine where urease (presumably of bacterial origin) hydrolyzes the urea. However, the amino acid synthesizing capacity of the intestinal microflora has not been studied. The series of steps, as outlined, would define the prevailing nitrogen conservation system for herbivores and omnivores at least. However, it would appear that some animals, in particular the fruit-eating bat and perhaps the fruit-eating bird, may have evolved alternative, as yet uncharacterized, adaptations to a very limited nitrogen intake.     

Zebrin II / Aldolase C Expression in the Cerebellum of the Western Diamondback Rattlesnake (Crotalus atrox)

Aldolase C, also known as Zebrin II (ZII), is a glycolytic enzyme that is expressed in cerebellar Purkinje cells of the vertebrate cerebellum. In both mammals and birds, ZII is expressed heterogeneously, such that there are sagittal stripes of Purkinje cells with high ZII expression (ZII+), alternating with stripes of Purkinje cells with little or no expression (ZII-). The patterns of ZII+ and ZII- stripes in the cerebellum of birds and mammals are strikingly similar, suggesting that it may have first evolved in the stem reptiles. In this study, we examined the expression of ZII in the cerebellum of the western diamondback rattlesnake (Crotalus atrox). In contrast to birds and mammals, the cerebellum of the rattlesnake is much smaller and simpler, consisting of a small, unfoliated dome of cells. A pattern of alternating ZII+ and ZII- sagittal stripes cells was not observed: rather all Purkinje cells were ZII+. This suggests that ZII stripes have either been lost in snakes or that they evolved convergently in birds and mammals.     

Parathyroid Glands in Reptiles

The parathyroid glands in reptiles generally develop from thethird and fourth pharyngeal pouches. In lizards and crocodiles,usually only one pair of glands (from the third pouch) persists,while turtles and snakes generally retain both pairs of glandsin adults. The glands consist of cell cords and are similarin structure to those of birds and mammals. A common featureof reptilian parathyroids is the organization of cells arounda lumen in a follicular arrangement. The few physiological studieswhich have been made indicate that parathyroid function in reptilesis in many respects similar to that of mammals. For example,in lizards, parathyroidectomy results in tetanic convulsionsand lowered values of plasma calcium, while administration ofparathyroid extract increases mine phosphate and serum calciumin turtles, and increases the number of osteoclasts in boneof lizards and turtles. However, there are some obvious differencesbetween parathyroid function in reptiles and mammals, on whichmuch more work is needed.     

Growth of young vertebrates in the egg or uterus

In eutherian mammals, foetal growth shows a straight-line relationship between time and cube root of foetal weight. The same relationship has now been found to hold for the embryos in birds' eggs and is postulated for reptiles. In marsupials the specific foetal growth rate does not exceed that already known for the higher primates. Outside the eutherian mammals, only the birds have developed high embryonic growth rates, but in exchange for other disadvantages.     

Quantitation of corneal fibril diameters from bony fish using low temperature preparative methods

Low-temperature dehydration and embedding techniques have been used to preserve the transverse structure of corneal collagen fibrils from nine bony fish. The diameters measured all lie close to a value of 25.5 nm, in contrast to the smaller (and more diverse) diameters measured from “conventionally” prepared controls. The results are consistent with our earlier studies on the corneas from mammals, amphibians, birds, reptiles, and cartilaginous and bony fish which showed that the collagen fibrils from the bony fish were significantly smaller than those from animals of the other vertebrate classes. Thus, on the basis of the enhanced ability of the low-temperature preparative techniques to preserve collagen fibril structure the “in vivo” corneal collagen fibril diameters have been revised from 17 to 25.5 nm for bony fish (this work) and from 25 to 36 nm for all other classes of vertebrates (our previous work).