Correcting eggshell indices of raptor eggs for hole size and eccentricity

Eggshell thickness is often expressed by means of an index based on the length, breadth and weight of the shell. The effect of the blow-hole and egg eccentricity on Ratcliffe's shell thickness index was investigated in a sample of 585 eggs from six raptor species. Corrections for the size of the hole and egg eccentricity are proposed, as is a combined formula to correct both sources of error at the same time. It is shown that by using these formulae, considerable improvements in estimates of shell thinning are obtained. These may be especially useful when sample sizes are small, which is often the case when working with species that have been reduced in numbers.     

cDNA cloning, expression pattern, genomic structure and chromosomal location of RAB6KIFL, a human kinesin-like gene

Purple acid phosphatases (PAPs) comprise a family of binuclear metal-containing hydrolases, members of which have been isolated from plants, mammals and fungi. Polypeptide chains differ in size (animal 35 kDa, plant 55 kDa) and exhibit low sequence homology between kingdoms but all residues involved in co-ordination of the metal ions are invariant. A search of genomic databases was undertaken using a sequence pattern which includes the conserved residues. Several novel potential PAP sequences were detected, including the first known examples from bacterial sources. Ten plant ESTs were also identified which, although possessing the conserved sequence pattern, were not homologous throughout their sequences to previously known plant PAPs. Based on these EST sequences, novel cDNAs from sweet potato, soybean, red kidney bean and Arabidopsis thaliana were cloned and sequenced. These sequences are more closely related to mammalian PAP than to previously characterized plant enzymes. Their predicted secondary structure is similar to that of the mammalian enzyme. A model of the sweet potato enzyme was generated based on the coordinates of pig PAP. These observations strongly suggest that the cloned cDNA sequences represent a second group of plant PAPs with properties more similar to the mammalian enzymes than to the high molecular weight plant enzymes.     

Field study of Haplochromis burtoni: Quantitative behavioural observations

Haplochromis burtoni observed in their natural habitat behave differently from those observed in aquaria in several respects. The majority of the territorial males observed in Lake Tanganyika living in a colony did not have the characteristic black eye bar as a part of their bright coloration, although otherwise the colour markings were identical. Those animals with eye bars appeared to be at a disadvantage in competition with barless fish for territories. The non-territorial males, females and juveniles are uniformly cryptically coloured and remained together in two or three large schools on the edge of the colony. These schools drifted slowly through the colony area, attempting to feed in the territories. Territorial males solicited females and chased non-territorial males. Sequences of behavioural events performed during courtship varied, depending on the local population density. Sound recordings showed no purposeful sounds associated with any behavioural acts.     

Territorial male color predicts agonistic behavior of conspecifics in a color polymorphic species

Male cichlid fish, Astatotilapia burtoni, live in a lek-likesocial system in shore pools of Lake Tanganyika, Africa, asone of two distinct social phenotypes: territorial (T) malesthat comprise approximately 10–30% of the population andnonterritorial (NT) males that make up the rest. T males arebrightly colored either blue or yellow with chromatic body patternsand are larger, reproductively capable, and defend territoriescontaining a food resource used to entice females to spawn withthem. NT males are camouflage colored, smaller, have regressedgonads, and shoal with females. Importantly, males shift betweenthese social states depending on their success in aggressiveencounters. It is not known whether there is a difference betweenyellow and blue T morphs. Here we asked whether T males preferentiallydefend their territory against a male of the same or oppositecolor. T males observed in social groups had agonistic interactionspredominantly with neighboring T males of the opposite color,and yellow morphs initiated significantly more aggressive interactions.When agonistic preference was tested experimentally, T maleshad significantly more agonistic interactions toward males ofthe opposite color, and yellow T males became territorial inthe majority of those interactions. Taken together, these resultssuggest that male coloration is an important social signal amongneighboring T males in this species and support the hypothesisthat T males differentially direct agonistic behavior dependingon the color of neighboring males.     

Bias Assessment of General Chemistry Analytes using Commutable Samples

Harmonisation of reference intervals for routine general chemistry analytes has been a goal for many years. Analytical bias may prevent this harmonisation. To determine if analytical bias is present when comparing methods, the use of commutable samples, or samples that have the same properties as the clinical samples routinely analysed, should be used as reference samples to eliminate the possibility of matrix effect. The use of commutable samples has improved the identification of unacceptable analytical performance in the Netherlands and Spain. The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) has undertaken a pilot study using commutable samples in an attempt to determine not only country specific reference intervals but to make them comparable between countries. Australia and New Zealand, through the Australasian Association of Clinical Biochemists (AACB), have also undertaken an assessment of analytical bias using commutable samples and determined that of the 27 general chemistry analytes studied, 19 showed sufficiently small between method biases as to not prevent harmonisation of reference intervals. Application of evidence based approaches including the determination of analytical bias using commutable material is necessary when seeking to harmonise reference intervals.     

Social context influences aggressive and courtship behavior in a cichlid fish

Social interactions require knowledge of the environment and status of others, which can be acquired indirectly by observing the behavior of others. When being observed, animals can also alter their signals based on who is watching. Here we observed how male cichlid fish (Astatotilapia burtoni) behave when being watched in two different contexts. In the first, we show that aggressive and courtship behaviors displayed by subordinate males depends critically on whether dominant males can see them, and in the second, we manipulated who was watching aggressive interactions and showed that dominant males will change their behavior depending on audience composition. In both cases, when a more dominant individual is out of view and the audience consists of more subordinate individuals, those males signal key social information to females by displaying courtship and dominant behaviors. In contrast, when a dominant male is present, males cease both aggression and courtship. These data suggest that males are keenly aware of their social environment and modulate their aggressive and courtship behaviors strategically for reproductive and social advantage.     

Food deprivation explains effects of mouthbrooding on ovaries and steroid hormones, but not brain neuropeptide and receptor mRNAs, in an African cichlid fish

Feeding behavior and reproduction are coordinately regulated by the brain via neurotransmitters, circulating hormones, and neuropeptides. Reduced feeding allows animals to engage in other behaviors important for fitness, including mating and parental care. Some fishes cease feeding for weeks at a time in order to provide care to their young by brooding them inside the male or female parent's mouth. Maternal mouthbrooding is known to impact circulating hormones and subsequent reproductive cycles, but neither the full effects of food deprivation nor the neural mechanisms are known. Here we ask what effects mouthbrooding has on several physiological processes including gonad and body mass, brain neuropeptide and receptor gene expression, and circulating steroid hormones in a mouthbrooding cichlid species, Astatotilapia burtoni. We ask whether any observed changes can be explained by food deprivation, and show that during mouthbrooding, ovary size and circulating levels of androgens and estrogens match those seen during food deprivation. Levels of gonadotropin-releasing hormone 1 (GnRH1) mRNA in the brain were low in food-deprived females compared to controls and in mouthbrooding females compared to gravid females. Levels of mRNA encoding two peptides involved in regulating feeding, hypocretin and cholecystokinin, were increased in the brains of food-deprived females. Brain mRNA levels of two receptors, GnRH receptor 2 and NPY receptor Y8c, were elevated in mouthbrooding females compared to the fed condition, but NPY receptor Y8b mRNA was differently regulated by mouthbrooding. These results suggest that many, but not all, of the characteristic physiological changes that occur during mouthbrooding are consequences of food deprivation.     

Female affiliative preference depends on reproductive state in the African cichlid fish, Astatotilapia burtoni

Hormones play a pivotal role in reproductive behavior and havebeen implicated in mediating mate choice decisions. Here weasked whether the differences in female reproductive state dependenton changes in hormone levels correspond to changes in femaleaffiliation with males. In the African cichlid fish, Astatotilapiaburtoni, males shift between reproductive (territorial; T) andnon-reproductive (non-territorial; NT) states depending on socialcontext while females alternate between gravid (egg bearing;G) and non-gravid (NG) reproductive states independent of socialconditions. Moreover, the brain-pituitary-gonadal axis controllingreproduction and reproductive hormones is substantially remodeledin both males and females depending on reproductive state. Tomeasure affiliative preference, gravid and non-gravid femaleswere given the choice of associating with T or NT males. Gravidfemales preferentially associated with T males, whereas non-gravidfemales showed no preference. To discover whether gravid femalesuse male size independent of dominance status as a cue for theirchoice, gravid females were given a choice between territorialmales of different sizes. Gravid females preferred the smallerof two T males, but the smaller T males were significantly moreactive. Our results show that associative change could be animportant behavioral mediator between hormonal cues and reproductivesuccess, and that females use a hierarchy of cues in decision-making,preferring to affiliate with T over NT males and, among T males,preferring more active animals.