The influence of washing treatment (dewatered only, one wash, and three washes) and sodium chloride (NaCl) concentration (0%, 2%, and 4%) on the gelation properties of crab mince was investigated. This previously cooked muscle mince is a low-value by-product of the crab processing industry, considered to have little or no functional properties. Crab mince gels were produced and tested for water-holding capacity (WHC), gel strength, colour, and electrophoretic profile. Wash treatment and NaCl concentration significantly affected gelation. Washed samples exhibited significantly higher WHC than dewatered samples. The 4% NaCl treatment decreased WHC compared to lower NaCl levels. Multiple washing steps increased the force to gel deformation. Wash treatment and NaCl concentration also affected the colour of gels. Based on these results, cooked crab meat mince treated with three washes and 0% NaCl resulted in the strongest gels with the best water-holding capacity, which can be used in the development of value-added products.

ABSTRACT: Crab processing typically involves picking meat from whole cooked product. Remaining meat can be recovered as mince and potentially processed into value‐added products. This study focused on gelation of commercially processed crab mince. Objectives of the research were to determine the effects of cryoprotectants, freezing, and various heat treatments on gel formation of washed mince from previously cooked crab. Previously frozen minced meat from thermally processed Jonah crab was washed to remove soluble components. Four different treatments were applied to the washed mince: (1) freezing with cryoprotectants, (2) freezing with no cryoprotectants, (3) no freezing with cryoprotectants, and (4) no freezing with no cryoprotectants. Unwashed mince was used as a control treatment. Sodium chloride (2.5%) was mixed into the mince prior to stuffing into sausage casings and heating at 35 °C/30 min, 90 °C/30 min, or 35 °C/30 min followed by 90 °C/30 min. Gels were tested for proximate composition, color, water‐holding capacity, and gel strength. All mince samples formed gels except for the unwashed control. Gels with no cryoprotectants had 10% to 20% greater water holding capacity, lower L* values, and greater gel strength than those with cryoprotectants. Freezing of washed mince resulted in lower water‐holding capacity of gels and higher a* values. A 2‐stage heating treatment resulted in gels with the greatest gel strength, whereas gels cooked at 35 °C had the greatest distance to fracture. Results indicate that protein gels can be formed using previously cooked crab meat, which may be useful in the development of value‐added products.

Levels of GH, PRL, and insulin in diabetic (db/db) mice were studied by radioimmunoassay. Serial blood samples from normal and diabetic mice of both sexes were obtained by orbital puncture at 5, 7, 10, 15, 20, 24, and 28 weeks of age; the final sample was obtained by decapitation at 32 weeks. Serum insulin and glucose levels in db/db mice were higher than normal throughout the study. Compared to those in normal controls, GH and PRL concentrations in the pituitary gland were 33 to 67% lower in db/db mice at 32 weeks of age. Serum GH levels in orbitally collected samples were also markedly subnormal in male diabetics; in females, the differences were not significant. GH levels in sera collected at 32 weeks were not significantly different from those of controls in either sex. PRL concentrations in the orbitally collected sera of db/db mice were lower than normal until 10-12 weeks of age; after this age the values approached normal levels. PRL concentrations in sera collected at decapitation were significantly lower than normal in db/db mice of both sexes. A single injection of perphenazine elicited a 20-fold rise in serum PRL concentrations in normal females; in db/db females, there were no increases. The results suggest generally deficient secretion of GH and PRL in the mutant db/db mouse.

In conjunction with studies relating the clearance rate of PRL with mammary tumor incidence, ws measured the MCR of GH in male, female, pregnant, and lactating mice of two strains, C3H/St (high incidence of mammary tumors) and C57BL/St (low incidence of mammary tumors). Mouse GH was administered by a single injection in the jugular vein of unanesthetized mice, and sera were collected from the orbit at frequent intervals up to 60 min. Sera were assayed for GH with a homologous RIA. The MCR of GH in male mice (C3H/St, 0.12 ± 0.02; C57BL/ St, 0.13 ± 0.01 ml/min) was not significantly different from that in females (C3H/St, 0.11 ± 0.01; C57BL/St, 0.11 ± 0.01 ml/min). Advanced pregnancy did not cause appreciable changes in the MCR of GH (C3H/St, 0.13 ± 0.01; C57BL/St, 0.08 ± 0.01 ml/min). The MCR increased nearly 2-fold, however, in lactating mice (C3H/St, 0.26 ± 0.01; C57BL/St, 0.22 ± 0.02 ml/min). The clearance rates in the two strains were similar in the male and virgin female states but averaged higher in the C3H/St strain during pregnancy and lactation. The secretion rate of GH was highest in pregnant mice (C3H/ St, 18.8 ± 3.1; C57BL/St, 8.2 ± 2.0 ng/min) and lowest in virgin females (C3H/St, 1.3 ± 0.1; C57BL/St, 1.0 ± 0.1 ng/min). Male mice of both strains had secretion rates (C3H/St, 1.9 ± 0.1; C57BL/St, 1.2 ± 0.3 ng/min) similar to those in females. Lactating mice had 3–4 times higher rates of GH secretion (C3H/St, 5.8 ± 0.5; C57BL/St, 4.0 ± 1.4 ng/min) than virgin females. The secretion rates in the two strains were virtually alike during all physiological states, except during pregnancy when the values were higher in the C3H/St strain. The results show that the serum concentrations of GH in mice do not always reflect the actual level of its secretion. Furthermore, they suggest that GH may play an important part in the maintenance of pregnancy and lactation in the mouse.

The MCR of PRL was measured in male, female, pregnant, and lactating mice of a high (C3H/St) and a low (C57BL/St) mammary tumor strain. Mouse PRL was administered by a single injection in the jugular vein of unanesthetized mice pretreated with 2-Br-α-ergocryptine, and sera were collected from the orbit at frequent intervals. Sera were assayed for PRL with a homologous RIA. The MCR of PRL in male mice (C3H/St, 0.45 ± 0.02; C57BL/St, 0.36 ± 0.02 ml/min) was 2–3 times higher than that in virgin females (C3H/St, 0.21 ± 0.01; C57BL/St, 0.10 ± 0.01 ml/min). The MCR did not change significantly during advanced pregnancy (C3H/St, 0.22 ± 0.02; C57BL/St, 0.06 ± 0.01 ml/min). However, the MCR increased sharply in lactating mice (C3H/ St, 0.42 ± 0.02; C57BL/St, 0.50 ± 0.04 ml/min). Except during nursing, the MCR was substantially higher in the high tumor C3H/St strain than in the low tumor C57BL/St strain. The secretion rate of PRL was highest in lactating mice (C3H/St, 123 ± 6; C57BL/St, 206 ± 29 ng/min) and lowest in virgin females (C3H/St, 7.5 ± 1.3; C57BL/St, 7.3 ± 1.6 ng/min). The secretion rate in male mice (C3H/St, 13.4 ± 2.0; C57BL/St, 10.8 ± 2.7 ng/min) was statistically indistinguishable from that in virgin females. Both strains had similar secretion rates at all stages, except during lactation when the secretion rate was higher in the C57BL/St strain. The results suggest that 1) the serum concentrations of PRL in mice do not always accurately reflect its level of secretion, 2) the rapid clearance rate of PRL may be associated with the development of mammary tumors in some strains of mice, and 3) PRL may have a wider function in male mice than is recognized.

Basal levels of GH and PRL in the serum and pituitary gland of normal (Pg/ Pg) and pygmy (pg/pg) (VY X C3H) F-l hybrid mice were measured by homologous radioimmunoassays. The serum concentrations of GH and PRL in pygmy mice at approximately 90 days of age were found to be no different from those in corresponding normal controls. The pituitary concentrations of the two hormones, however, were substantially subnormal in pygmy mice. Perphena-zine injection failed to stimulate PRL release by pygmy (pg/pg) pituitaries, in contrast to the marked increase in serum PRL levels of the normal Pg/Pg mice. Daily administration of 100 μg of ovine PRL for 8 weeks produced none or very little increase in the body weight of pygmy mice. These results suggest that the pg mutation induces a multifaceted change affecting the synthesis, release, and function of growth hormone and prolactin.

Monomeric mouse prolactin containing small amounts of 125I-labelled prolactin was administered to adult female mice of a high (C3H/St) and low (C57BL/St) mammary tumour strain. Their endogenous prolactin had been suppressed with 2-bromo-alpha-ergocryptine. The chromatographic profile, on Sephadex G-100, of prolactin in the serum of mice injected with mouse prolactin was compared by direct measurement (radioactivity count) and by radioimmunoassay (RIA) at several intervals after injection. With both methods, the injected hormone was found in the serum in predominantly two molecular sizes, the so-called 'big' and 'little' forms. Although 'little' prolactin in both strains constituted a constant 80% of the total hormone at most intervals by direct measurement, it comprised a comparatively smaller proportion by RIA. In addition, the RIA-determined 'little' prolactin, after reaching maximum levels at 15 min, progressively decreased with time, the decrease being greater in the C3H/St than in the C57BL/St strain. Similar experiments with mouse growth hormone revealed no such discrepancies between the radioactivity counts and the RIA measurements. A fraction of both 'big' and 'little' forms in the C3H/St strain failed to precipitate completely after the material had been incubated with an antiserum to mouse prolactin. These results demonstrate that the prolactin injected into mice is metabolized in serum into two non-immunoreactive forms, one that elutes with the same elution volume on Sephadex G-100 column as the monomer and the other that elutes as the 'big' form. Furthermore, the loss of immunoreactivity of monomeric mouse prolactin is greater in the high-tumour C3H/St strain than in the low-tumour C57BL/St strain. Endogenous immunoreactive prolactin, on the other hand, was found mainly in the 'big' form in the serum of female mice of the C3H/St strain under basal conditions, whereas it was present only in the 'little' form in comparable mice of the C57BL/St strain, even though pituitary extracts of both strains contained mainly the 'little' form. These results support the concept that monomeric prolactin in the systemic circulation of the tumour-prone C3H/St strain is largely in a non-immunoreactive form.

Polyacrylamide gel electrophoresis of fresh mouse pituitary extracts in 10% acrylamide reveals three closely situated bands of protein in the area where prolactin usually migrates. The fastest migrating band constitutes only 10–30% of the total, but it is twice as active in the pigeon crop-sac bioassay as the major band and has little or no immunologic cross-reactivity against an antiserum to the major constituent. This newly recognized band may be a hitherto unrecognized molecular variant of prolactin.

SUMMARY Pseudopregnancy was induced in 61% of C57BL/St mice that were stimulated cervically with a glass rod for 30 s on the day of oestrus. Within 60 min of stimulation, the concentration of prolactin in the serum increased threefold and appeared to be released in a phasic manner. Subsequently, prolactin was secreted at an enhanced rate for approximately two-thirds of pseudopregnancy, as the level in the serum rose and the level in the pituitary gland dropped. The concentrations of growth hormone (GH) in the serum showed only a minor increase 8 h after cervical stimulation, with no significant rise during the course of pseudopregnancy. Pituitary GH concentrations increased between early and late pseudopregnancy. The DNA and RNA contents of the mammary glands, indices of mammary gland growth and metabolic activity, were both enhanced during pseudopregnancy and paralleled the increases in the secretion of prolactin, whereas mammary gland weight generally followed changes in the level of GH in the pituitary gland. Administration of the prolactin inhibitor 2-bromo-α-ergocryptine reduced the incidence of pseudopregnancy, but neither an inhibitor of GH release, somatostatin, nor an antiserum to mouse GH had any appreciable effects. Injections of ovine prolactin and mouse GH induced the dioestrous state in mice, but only ovine prolactin stimulated the growth of corpora lutea. These results suggest that prolactin is the main hormone involved in the induction and maintenance of pseudopregnancy in the mouse. Injections of ovine prolactin or mouse GH suppressed endogenous levels of the respective hormone; however, prolactin also reduced the level of GH and GH reduced the level of prolactin, suggesting that pituitary hormones can influence not only their own secretion but that of other pituitary hormones as well.