Wyniki wyszukiwania - AGRO

1

A new four-parameter, generalized logistic equation and its applications to mammalian somatic growth

100%

Wan X., Wang M., Wang G., Zhong W.

Acta Theriologica

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2000

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tom 45

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nr 2

A new mathematical equation is introduced in this paper: w = f - 1/(b/f +(1/(f-s)-b-f)exp(kt)) where W is the size at any convenient unit of time /, s is the initial size, f is the upper asympotic size, k is the growth coefficient (k > 0), and b is the constant. The new equation encompasses the logistic equation and therefore should be considered as a generalized version of the classical logistic equation. With its additional fourth parameter 6, the new equation yields an unfixed value of inflexion point which enables it to possess good flexibility for depicting diverse growth patterns. In order to evaluate the fitness of the new growth equation, some commonly encountered models are compared to the new one using 12 sets of somatic growth data of mammalian species including hamster, rat, vole, pika, mouse, rabbit, cattle, and bear, The new equation possesses excellent fitness to each data set, suggesting that it is worth being considered by growth data analysts.

2

Supernormal excitability in the Luo-Rudy I model of the mammalian ventricular cell

100%

Cieniawa J., Gawda H.

Cellular and Molecular Biology Letters

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2002

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tom 07

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nr Suppl.

3

Recent studies on molecular mechanisms involved in mammalian sperm capacitation: A review

88%

Katska-Ksiazkiewicz L.

Journal of Animal and Feed Sciences

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2007

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tom 16

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nr 3

311-328

4

Mammalian post-natal test of vitality presented on a Bos taurus model

88%

Mayntz M., Sender G.

Animal Science Papers and Reports

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2006

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tom 24

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nr 4

5

Role of genomic imprinting in endosperm development

88%

Scott R. J., Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, U.K.

Acta Biologica Cracoviensia. Series Botanica. Supplement

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2005

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tom 47

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nr 1

6

Conserving patterns of genetic diversity in endangered mammals by captive breeding

88%

Schreiber A., Kolter L., Kaumanns W.

Acta Theriologica. Supplement

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1993

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tom 38

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nr 2

Breeding endangered mammals for their conservation requires knowledge about the genetic architecture of the respective species. In taxa with tight genetic cohesion between populations, the definition of management units for captive breeding rarely poses problems, except if there are morphologically well differentiated subspecies grading into one another although they are hardly separate at the molecular level. Species with genetic diversity predominantly between populations can pose serious problems for breeders. Examples are discussed of mammalian species with complex genetic architectures, where decisions have to be drawn whether to select only certain populations for conservation, or to create an artificial taxon. Research into subspecific molecular taxonomy of rare zoo-living wildlife is frequently hampered by small sample sizes available for study, with the risk of spurious molecular taxonomie distances based on marker allele frequencies in populations influenced by genetic drift. "Typological" approaches are suggested for molecular systematics of such study material, with the haplotype organization of polymorphic MHC genes appearing particularly promising. Additional molecular approaches, not easily susceptible to sample size problems, are shortly presented. The implementation of breeding plans to achieve conservation genetic goals may interfere with the social structures of the animals. This group of problems includes the transfer of socially compatible individuals to form new groups, and the provision of suitable sexual partners for mate choice mechanisms to act in their species-specific manner. A survey of scientific research in European zoos is provided to recognize what is being done to fight the current ignorance about basic aspects of the conservation biology of many endangered mammals.

7

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Unique anatomy of lagomorph calcaneus

88%

Bleefeld A. R., Bock W. J.

Acta Palaeontologica Polonica

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2002

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tom 47

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nr 1

The mammalian order Lagomorpha (hares, rabbits, pikas) comprises two families (Ochotonidae and Leporidae; McKenna and Bell 1998; Nowak 1999), and Recent members have a nearly world−wide distribution (Hoffman 1993; Nowak 1999). Detailed examination of the pedal morphology of extant and fossil lagomorphs revealed a unique channel (the “calcaneal canal”) running diagonally through the lagomorph calcaneus. The ancientness, ubiquity, and appearance of the calcaneal canal in all, including the earliest recognized lagomorph calcanea, and its absence from the pedes of other mammalian taxa, may indicate a long evolutionary separation of lagomorphs from other, previously suggested lagomorph relatives.

8

The ratio of amount of haemoglobin to total surface area of erythrocytes in mammals

88%

Kostelecka-Myrcha A.

Acta Theriologica. Supplement

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2002

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tom 47

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nr 1

The literature provides all the data needed to calculate the ratio between the amount of haemoglobin and the total surface area of erythrocytes in 54 species of mammals ranging in body mass from 2.5 g to more than 1000 kg. Analysis shows that the concentration of haemoglobin (Hb; g%) does not defend on the body mass ofthe mammals studied. The number of erythrocytes in 1 mm of blood (RBC; 10 x mm ) is significantly lower, and the diameter of these cells significantly higher, among larger mammals as opposed to smaller ones. The result is that the total surface area of erythrocytes in 1 mm of blood (TSAE; mm x mm ) is significantly lower among larger mammals, while the Hb/TSAE ratio (pg x ^m- ) is significantly greater. These results point to the smaller size of erythrocytes of smaller mammals permitting much greater numbers to exist, thereby producing a greater TSAE and smaller Hb/TSAE ratio. The greater total surface area of red blood cells per unit volume of blood in small mammals can in turn be presumed to allow for full saturation of haemoglobin by oxygen, even where the period of contact between erythrocytes and air in the lungs is shorter than in their larger counterparts.

9

Genomic imprinting in mammals

88%

Wrzeska M., Rejduch B.

Journal of Applied Genetics

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2004

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tom 45

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nr 4

10

Tracking mammal body size distributions in the fossil record: a preliminary test of the rule of limiting similarity

88%

Martin R. A.

Acta Zoologica Cracoviensia

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1996

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tom 39

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nr 1

11

Poleomagnetic calibration of Plio-Pleistocene mammal localities in central Italy

88%

Torre D., Albianelli A., Bertini A., Ficcarelli G., Masini F., Napoleone G.

Acta Zoologica Cracoviensia

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1996

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tom 39

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nr 1

12

The structure of groupings of helminths of small mammals from the Region of Karkonosze

88%

Gadomska K., Karbowiak G., Wita I., Andrzejewska K.

Wiadomości Parazytologiczne

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1998

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tom 44

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nr 3

13

Genetic mechanisms underlying male sex determination in mammals

75%

Piprek R. P.

Journal of Applied Genetics

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2009

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tom 50

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nr 4

347-360

Genetic control of gonadal development proceeds through either the male or female molecular pathways, driving bipotential gonadal anlage differentiation into a testis or ovary. Antagonistic interactions between the 2 pathways determine the gonadal sex. Essentially sex determination is the enhancement of one of the 2 pathways according to genetic sex. Initially, Sry with other factors upregulates Sox9 expression in XY individuals. Afterwards the expression of Sox9 is maintained by a positive feedback loop with Fgf9 and prostaglandin D₂ as well as by autoregulative ability of Sox9. If these factors reach high concentrations, then Sox9 and/or Fgf9 may inhibit the female pathway. Surprisingly, splicing, nuclear transport, and extramatrix proteins may be involved in sex determination. The male sex determination pathway switches on the expression of genes driving Sertoli cell differentiation. Sertoli cells orchestrate testicular differentiation. In the absence of Sry, the predomination of the female pathway results in the realization of a robust genetic program that drives ovarian differentiation.

14

How does evolution build a complex brain

75%

Krubitzer L.

Acta Neurobiologiae Experimentalis

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2005

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tom 65

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nr 5

15

Evolutionary radiation of the cheek teeth of Cretaceous placentals

75%

Butler P. M.

Acta Palaeontologica Polonica

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1977

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tom 22

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nr 3

Included is a comparative study of the molars and posterior premolars of the Cretaceous placentals. Particular attention is paid to occlusal relations. An attempt is made to identify primitive characters, and the advance of each genus from the primitve condition is analysed. It is found that nearly all known genera are on different lines of evolution, indicating that a major radiation of placentals was taking place during the Cretaceous.

16

Bats (Chiroptera) of the Silesian Beskid Mountains

75%

Myslajek R., Kurek K., Szura C., Nowak S., Orysiak P.

Fragmenta Faunistica

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2007

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tom 50

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nr 1

17

A mechanical link model of two-toed sloths: no pendular mechanics during suspensory locomotion

75%

Nyakatura J. A., Andrada E.

Acta Theriologica

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2013

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tom 58

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nr 1

Sloths are morphologically specialized in suspensory quadrupedal locomotion and posture. During steady-state locomotion they utilize a trot-like footfall sequence. Contrasting the growing amount of published accounts of the functional morphology and kinematics of sloth locomotion, no study concerned with the dynamics of their quadrupedal suspensory locomotion has been conducted. Brachiating primates have been shown to travel at low mechanical costs using pendular mechanics, but this is associated with considerable dynamic forces exerted onto the support. To test whether sloth locomotion can be described by simple connected pendulum mechanics, we analyzed the dynamics of sloth locomotion with use of a mechanical segment link model. The model integrates the body segment parameters and is driven by kinematic data with both segment parameters and kinematic data obtained from the same sloth individual. No simple pendular mechanics were present. We then used the model to carry out an inverse dynamic analysis. The analysis allowed us to estimate net limb joint torques and substrate reaction forces during the contact phases. Predominant flexing limb joint torque profiles in the shoulder, elbow, hip, and knee are in stark contrast to published dominant extensor torques in the limb joints of pronograde quadrupedal mammals. This dissimilarity likely reflects the inverse orientation of the sloth towards the gravity vector. Nevertheless, scapular pivot and shoulder seem to provide the strongest torque for progression as expected based on unchanged basic kinematic pattern previously described. Our model predicts that sloths actively reduce the dynamical forces and moments that are transmitted onto the support. We conclude that these findings reflect the need to reduce the risk of breaking supports because in this case sloths would likely be unable to react quickly enough to prevent potentially lethal falls. To achieve this, sloths seem to avoid the dynamical consequences of effective pendular mechanics.

18

Mitochondria and aging: innocent bystanders or guilty parties?

75%

Tonska K., Solyga A., Bartnik E.

Journal of Applied Genetics

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2009

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tom 50

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nr 1

55-62

There are many theories of aging and a number of them encompass the role of mitochondria in this process. Mitochondrial DNA mutations and deletions have been shown to accumulate in many tissues in mammals during aging. However, there is little evidence that these mutations could affect the functioning of aging tissues.

19

Osmotic and nonosmotic influences on thermoregulatory evaporation in dehydration and rehydration

75%

Beker M. A., Turlejska E.

Acta Physiologica Polonica

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1990

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tom 41

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nr 1-3

20

Do decibels matter? A review of effects of traffic noise on terrestrial small mammals and bats

75%

Bednarz P. A.

Polish Journal of Ecology

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2020

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tom 68

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nr 4

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